Topic 6 & 11: Human & Animal Health & Physiology
Your body won't produce antibodies to the
antigens of your blood group.
term meaning having two copies of each chromosome
diploid
Alpha cells produce
glucagon
Label this:
Arteriole
0.005mm
5um =
What surrounds the egg in the womb?
A mucus plug forms inside the cervix (opening to the uterus) to protect the baby from bacteria during pregnancy.
Remember: ADH is produced when you
Are DeHydrated
What is found in gallbladder?
Bile
Lymphocytes divide by mitosis.
How do lymphocytes divide?
A = Artery B = Capillary C = Vein
Identification of Blood Vessels
Functional unit of the kidney - you find many of these in each kidney
Nephron
Muscular movement associated with transporting food:
Peristalsis
Where do you store feces?
Rectum
How long does skeletal muscle contraction last?
Skeletal muscle contraction lasts (the sliding of filaments) until there is no more ATP that bind to myosin heads and Ca ions that bind to troponin.
At the moment this membrane is at resting potential, which ions are outside?
Sodium (Na+) = pink.
blood at high pressure from the heart ventricles to the tissues of the body and lungs
The function of arteries is to convey
pacemaker
The sinoatrial node acts as a
mitosis
activated lymphocyte divides many times by
umbilical ... The blood vessel which travels from the baby to the placenta
artery
Boyles Law
as volume increases, pressure decreases -as volume decrease, pressure increases
The stomach turns food into a creamy paste called
chyme.
bile function
digest fat; excrete waste
Maternal venuolue
takes waste, like CO2, urea and hormones (eg. hCG) from the baby.
as percent protein increases, density increases
Data-based Q: 1 (ii)
as percent cholesterol increases, density increases
Data-based Q: 1 (iii)
1a: microvilli
Data-based Q: 1a
1b: site of absorption; structure maximises SA to volume ratio.
Data-based Q: 1b
all-round malnutrition due to drought and food shortages; land unsuitable to support dairy farming; farming meat may be too expensive.
Data-based Q: 1b
1c: (20 mm image) / (0.85 mm) = x23.5 magnificaition
Data-based Q: 1c
Digestible matter increases mean residence time; reduced fibre reduces transit rate and extra water is reabsorbed in the colon.
Data-based Q: 2
the % cholesterol is very similar in both
Data-based Q: 2
Africa = 4.00 YLD/1000 (+/-0.05), W. Europe = 0.10 YLD/1000 (+/-0.05); % difference = 4.00/0.10 * 100 = 4000% difference.
Data-based Q: 2a
Purple structures
Data-based Q: 2a
increased food aid; supplies of milk; supplementation; financial aid for farming; reduce western demand for meat, which would lead to less pressure on land.
Data-based Q: 2b
to provide ATP for active transport
Data-based Q: 2b
because LDL contain higher levels of cholesterol which can contribute to plaque formation.
Data-based Q: 3
Endocytosis
Data-based Q: 3a
in all regions except Africa, there was a decrease in YLD/1000 between 1990 and 2000.
Data-based Q: 3a
Lipids
Data-based Q: 3b
biggest improvement in S. & C. America
Data-based Q: 3b
possible due to imported food products from the USA; increased economic stability; increase in agricultural production; etc.
Data-based Q: 3c
tight junction function
Data-based Q: 4a
to hold tissues together/prevent passage of materials.
Data-based Q: 4b
Term used to describe a condition where the body is short of water
Dehydration
What ions are causing depolarisation?
Depolarization is caused when positively charged sodium ions rush into a neuron with the opening of voltage-gated sodium channels (low sodium outside).
Region of the nephron which plays a role in pH regulation of body fluids (3 Words)
Distal Convoluted Tubule (DCT)
Antigen: A substance that the body recognises as foreign and that can evoke an immune response Antibody: A protein produced by certain white blood cells (B lymphocytes, plasma cells) in response to an antigen
Distinguish between antigens and antibodies
Explain how the structure of the villus is related to its role in absorption and transport of products of digestion
Microvilli: Greatly increase the surface area of the villus, allowing for a greater rate of absorption Rich capillary networks: Help to maintain a concentration gradient for absorption by rapidly transporting absorbed products away Single epithelial layer: Ensures minimal diffusion distance between the intestinal lumen and capillary network Lacteals: Absorb lipids from the intestine into the lymphatic system (which are later reabsorbed back into normal circulation) Intestinal crypts: Located between villi and release juices that act as a carrier fluid for nutrients Membrane proteins / mitochondria: High amounts to enable active transport into cells (contents then passively diffuse into bloodstream)
Antibodies aid in the destruction of pathogens by a number of different mechanisms:
Mnemonic: PANIC Precipitation - Soluble pathogens become insoluble and precipitate Agglutination - Cellular pathogens become clumped for easier removal Neutralisation - Antibodies may occlude pathogenic regions (e.g. exotoxins) Inflammation - Antibodies may trigger an inflammatory response within the body Complement activation - Complement proteins perforate membranes (cell lysis)
Erythrocyte percentage increased AND body mass reduced/smaller increase in mass
Hypoxia is a condition in which tissues of the body are deprived of an adequate oxygen supply. A study was carried out in rats to examine the effects of continuing hypoxia on the structure of the diaphragm, and to determine whether nitric oxide is implicated in adaptation of the diaphragm to hypoxia. The diaphragm helps to supply oxygen to tissues and organs in the body by ventilating the lungs. The right ventricle is an area of the heart that pumps blood to the lungs for oxygenation. An erythrocyte is a red blood cell. A group of 36 adult male rats were kept for 6 weeks in low oxygen while 36 adult male rats were kept in normal oxygen levels. Outline the effect of hypoxia on body mass and erythrocyte percentage. [1 mark]
a secondary pacemaker (AV node) may maintain cardiac contractions at roughly 40 - 60 bpm
If the SA node fails,
By whom has IVF been used?
It has been used extensively to overcome fertility problems in either the male or female parent.
Ultrafiltration is the first of three processes by which metabolic wastes are separated from the blood and urine is formed:
It is the non-specific filtration of the blood under high pressure and occurs in the Bowman's capsule of the nephron
Why do you have to excrete CO2?
It makes the pH more acidic, which causes proteins to denature.
Jaundice
Jaundice is caused by a buildup of bilirubin, a waste material, in the blood. An inflamed liver or obstructed bile duct can lead to jaundice, as well as other underlying conditions. Symptoms include a yellow tinge to the skin and whites of the eyes, dark urine, and itchiness.
Drawing of a Human Digestive System
Key Features: - Stomach should look like a 'J'-shaped bag and be connected to the oesophagus and small intestine - Liver should look like a right-angled triangle and be superimposed to the left of the stomach (right side of the human) - Bile duct (connected to gall bladder) and pancreatic duct should both feed into a U-shaped bend of the small intestine - Small intestine should be thinner in width than the large intestine
Explain why digestion of large food molecules is essential
Large molecules need to be broken down into smaller molecules that can be readily absorbed across membranes and into cells.
Why is Lung Cancer usually fatal when it is discovered?
Lung cancer is usually fatal as it is only discovered at a late stage when the primary tumour is large and secondary tumours have already developed elsewhere in the body.
Many different methods are used to move the products of digestion into the villus epithelial cells. Absorption of fructose:
Many hydrophilic molecules are absorbed by facilitated diffusion using proteins in the membrane of the microvilli. An example would be the monosaccharide fructose.
What event happens when they do decline?
Menstrual period / bleeding
More on muscle fibre structure:
Each myofibril (within a muscle fibre) is surrounded by a specialised type of endoplasmic reticulum called sarcoplasmic reticulum. Its function is to store calcium which is needed in order for muscle contraction in response to nervous stimulation. In the centre of each light band is a disc shaped structure called a Z disc or a Z line. From the German, "Zwischenscheibe" - which means "in between".
Bulk Transport
Endocytosis involves the invagination of the plasma membrane to create an internal vesicle containing extracellular material, which requires the breaking and reforming of the phospholipid bilayer and hence is an energy-dependent process (need ATP).
the heart rate to prepare for vigorous physical activity
Epinephrine increases
CO2 is a waste product of the body, what do we call getting rid of CO2?
Excretion
What advantages would the experiment if I had air or oxygen in the spirometer?
Experiment would go on for much longer. --> pure oxygen.
1. Blood returning from all parts of the body (except lungs) enter the right atrium via the vena cava - this blood is relatively deoxygenated 2. The blood passes from the right atrium to the right ventricle and then via the pulmonary artery to the lungs (where blood is reoxygenated). 3. The blood returns to the left atrium via the pulmonary vein and passes through the left ventricle to the aorta, where it is pumped around the body.
Explain the action of the heart in terms of collecting blood, pumping blood and opening and closing valves:
On the Motion of the Heart and Blood
Harvey's findings were published in a book commonly called De Motu Cordis -
Treatment of Kidney failure
Hemodialysis and kidney transplants as treatments for kidney failure.
Air out (exhale):
Higher CO2, Lower O2
1. In the airways pathogens are trapped in the sticky mucus. 2. They can be moved from the airways using cilia to push the mucus out of the trachea to the throat where the bacterial and dust laden mucus can be swallowed. Not all mucous membranes in the body have cilia. 3. The production of lactic acid and fatty acids reduces the pH of the protective mucus. 4. Lysozyme enzyme (a hydrolytic enzyme) found in the mucus helps to destroy bacteria.
How are mucous membranes used to trap pathogens in the airways?
C)B cells with myeloma cells
Hybhidomas are made from combining A)monoclonal antibodies with myeloma cells B)B cells with specific epitopes C)B cells with myeloma cells D)T cells with myeloma cells E)monoclonal antigens with myeloma cells
the production of commercial amounts of a single antibody by creating a cancerous plasma cell that continues to divide and divide. These antibodies have numerous commercial applications.
Hybridoma (hybrid = mixture of two cells, "oma" is coming from cancer e.g a melanoma) cells are used for
What ions are causing hyperpolarisation?
Hyperpolarization occurs due to an excess of open potassium channels and potassium efflux from the cell.
Adaptation of the plasma membrane found in cells adapted for selective reabsorption
Microvilli
What would you not find in the DCT?
Not find amino acids, glucose, but some water you would find + you would also find urea.
1. Antigens that correspond to the desired antibody are injected into an animal - usually a mouse. 2. Plasma cells that produce the desired antibody are extracted from the animal. 3. Myeloma cells are a type of cancerous plasma cell ("myelo" is the Greek for marrow and "oma"; is the Greek for a tumor), which can be obtained from existing cultures. 4. The plasma cells obtained from the mouse are fused with the myeloma cells. 5. This result is the formation of hybridoma cells. 6. The hybridoma cells are grown and the antibodies they produce (only one type) are extracted and purified. 7. They are called monoclonal antibodies because they are produced from one clone of hybridoma cells. 8. EXAMPLE: monoclonal antibodies are used to detect hCG, a protein which is found in the urine of pregnant women, which is hence used in pregnancy kits to show if the woman is pregnant or not.
Monoclonal antibodies
If blood glucose is too high
Plasmolysis (cell shrinks)
What do you call a shrunken cell?
Plasmolyzed (cell shrinks)
1. Antigens that correspond to the desired antibody are injected into an animal - usually a mouse. 2. Plasma cells that produce the desired antibody are extracted from the animal - usually from the spleen. 3. Myeloma cells are a type of cancerous plasma cell ("myelo" is the Greek for marrow and "oma" is the Greek for a tumor). They can be obtained from existing cultures. 4. The plasma cells obtained from the mouse (against one specific/the desired antigen) are fused with the myeloma cells. This result is the formation of hybridoma cells. 5. The hybridoma cells are grown and the antibodies they produce (only one type) are extracted and purified. 6. The identical antibodies extracted are purified are called monoclonal antibodies because they are produced from one clone of hybridoma cells. 7. In pregnancy test kits the monoclonal antibodies found in the kit bind to a hormone called hCG. This protein is found in the urine of pregnant women having been produced by the developing embryo and later the placenta. If hCG is present a coloured band appears on the test kit and the woman is pregnant. In the case below the urine was moving from left to right. The line on the far right tells the woman that the urine did pass through the "test area" just prior to this region. It other word the test is valid. (You don't need to know how this works, just that it is an example of the uses of monoclonal antibodies to detect hCG protein. A colour change results if the antigen/HCG is present.)
Production of Hybridoma Cells for the production of commercial amounts of monoclonal antibody (a single antibody):
What should not be found in the urine (should have been filtered out)?
Red blood cells (parasite, infection, cancer), white blood cells, large protein (smaller proteins like hCG can be found = indicators for pregnancy in pregnancy tests), glucose (can not get all out / filter = diabetes), amino acids, (bacteria and drugs too = can be tested in urine tests) should be kept in the blood. These components should not be present in urine. water and salt is needed by the body and will remain in the blood.
Where are red blood cells made?
Red blood cells are formed by stem cells in the bone marrow of bones.
Skeletal muscle is striated/striped. Between the stripes are repeating units called ______.
SARCOMERES
a. decrease in volume/atrophy/loss of cells/less muscle fibres/less tissue in the diaphragm b. SA to volume ratio increased to make oxygen uptake into muscle/cells faster
Skeletal muscle contractions can take two different forms: if they are stimulated by a single nervous impulse, they take the form of a twitch and if they are stimulated by a series of nerve impulses the contraction is longer lasting (tetanic). The table shows the effects of hypoxia on the force of twitch and peak tetanic contraction in the diaphragm. Hypoxia caused a 13 % increase in the surface area to volume ratio of the diaphragm. Suggest a reason for this change. [1 mark]
reduces (force of) twitch AND peak tetanic contraction
Skeletal muscle contractions can take two different forms: if they are stimulated by a single nervous impulse, they take the form of a twitch and if they are stimulated by a series of nerve impulses the contraction is longer lasting (tetanic). The table shows the effects of hypoxia on the force of twitch and peak tetanic contraction in the diaphragm. Outline the effect of hypoxia on the force of contraction of the diaphragm. [1 mark]
Is air just oxygen (the air that you inhale)?
No, the air you breath in contains a variety of gases, it contains oxygen (21% = 1/5th), nitrogen (78% = 4/5th), CO2 (0.04% = 4/100th) water vapour (H2O gas = the % depends on the conditions, whether it is a very dry day or humid),
Do your nerve cells touch eachother?
No, there's a gap between them (synapse)
1) Blood returning to the heart will flow into the atria and ventricles as the pressure in them is lower (due to low volume of blood) 2) When ventricles are ~70% full, atria will contract (atrial systole), increasing pressure in the atria and forcing blood into ventricles 3) As ventricles contract, ventricular pressure exceeds atrial pressure and AV valves close to prevent back flow (first heart sound) 4) With both sets of heart valves closed, pressure rapidly builds in the contracting ventricles (isovolumetric contraction) 5) When ventricular pressure exceeds blood pressure in the aorta, the aortic valve opens and blood is released into the aorta
Systole
host/your cells that have pathogens already inside, or on, them. They kill the infected cell together with its pathogen invaders still inside.
T cells attack
1. The walls of the atria contract, pushing blood from the atria into the ventricles through the atrio-ventricular valves, which are open. The semilunar valves are closed, so the ventricles fill with blood. 2. The walls of the ventricles contract power fully and the blood pressure rapidly rises inside them.This first causes the atrio-ventricular valves to close, preventing back-flow to the atria and then causes the semilunar valves to open, allowing blood to be pumped out into the arteries. At the same time the atria start to refill by collecting blood from the veins. 3. The ventricles stop contracting so pressure falls inside them. The semilunar valves close, preventing back-flow from the arteries to the ventricles. When the ventricular pressure drops below the atrial pressure, the atrio-ventricular valves open. Blood entering the atrium from the veins then flows on to start filling the ventricles. The next cardiac cycle begins when the walls of the atria contract again.
The beating of the heart consists of a cycle of actions:
Diastole
The cardiac cycle describes the series of events that take place in the heart over the duration of a single heart beat. It is comprised of a period of contraction (systole) and relaxation:
Systole
The cardiac cycle describes the series of events that take place in the heart over the duration of a single heart beat. It is comprised of a period of contraction:
a. increases endurance (in relation to the control) b. higher force/endurance at every testing time/throughout OR smaller decreases in force (over time) c. the magnitude of the difference is similar throughout the five minutes experiment/testing d. differences are (statistically) significant e. endurance of control is (approximately) 35 % versus endurance of hypoxia (approximately) 55 % (after 5 minutes) Accept ±5 % for both percentages
The graph shows the effect of hypoxia on the endurance of rats' diaphragm muscle after 6 weeks. Endurance is the change in force measured as a percentage of the initial force. Using the data in the graph, deduce whether hypoxia increases or decreases the endurance of the rats' diaphragm muscle. [2 marks]
Comparison of Spermatogenesis and Oogenesis: Production ends
Spermatogenesis: Continues throughout the male adult life. Oogenesis: During menopause.
Comparison of Spermatogenesis and Oogenesis: Production begins
Spermatogenesis: In puberty. Oogenesis: During fetal development.
Comparison of Spermatogenesis and Oogenesis: Completion of the second division of meiosis occurs.
Spermatogenesis: before fertilisation. Oogenesis: after fertilisation.
Comparison of Spermatogenesis and Oogenesis: Released upon...
Spermatogenesis: ejaculation (sperm). Oogenesis: ovulation (eggs / ovum = day 14 of menstrual cycle).
Comparison of Spermatogenesis and Oogenesis: Meiotic divisions
Spermatogenesis: equal division of cytoplasm (4 similar sized products. Oogenesis: unequal division of cytoplasm (one large egg and 2 small polar bodies).
Comparison of Spermatogenesis and Oogenesis: Meiotic products
Spermatogenesis: x4 spermatozoa (4 sperms produced per meiotic event). Oogenesis: x1 mature egg and 2-3 polar bodies.
Comparison of Spermatogenesis and Oogenesis: Involves sertoli cells?
Spermatogenesis: yes (involves sertoli / nurse cells, because sperm cells differentiate using nurse cells). Oogenesis: no.
A. Arteries B. Capillaries C. Veins
Structure of Blood Vessels
1. They have a very wide lumen (relative to wall thickness) to maximise blood flow for more effective return 2. They have a thin wall containing less muscle and elastic fibres as blood is flowing at a very low pressure (~ 5 - 10 mmHg) 3. Because the pressure is low, veins possess valves to prevent backflow and stop the blood from pooling at the lowest extremities
Structure of a Typical Vein
What does oestrogen appear to do in the uterus?
Supports development of uterine lining
You may be given a light microscope picture (light micrograph) of a section of skeletal muscle. Skeletal muscle is striated/striped. Between the stripes are repeating units called SARCOMERES. In given the image below you should be able to calculate the approximate length of one sarcomere. The image below is magnified 200 times (200x):
This would be one way to do this: 1. Measure the length of 10 sarcomeres in mm. This can be measured from the middle of a light area to the middle of a light area 10 (light areas) ahead. 2. Divide by 10 to calculate the length of 1 sarcomere in mm. 3. Then change to micrometres by multiplying by 1000. 4. Now divide by 200 to get to the actual length of one sarcomere.
1. Some strains of bacteria have evolved with genes that confer resistance to antibiotics. 2. This is a present day example of evolution in action. Some strains of bacteria have evolved resistance to multiple antibiotics. 3. MRSA which stands for Methicillin Resistant Staphylococcus aureus is one such organism and is a major concern after invasive surgery. It is resistant to all of the penicillin family antibiotics.
What are antibiotic resistant bacteria?
blood platelets: they are part of the clotting process and they have no nucleus.
What are thrombocytes?
A similar cascade reaction to the formation of a plaque occurs in a coronary artery in response to damage to the inner lining of the artery called the endothelium layer and this brings about a blockage/clot/thrombus in the coronary artery which precipitates a heart attack.
What is a cascade reaction similar to a plaque (or atheroma)?
a group genetically identical cells (from the same parent).
What is a clone?
1. A unicellular gland that produces mucus. 2. Goblet cells are well adapted to the production of proteins that are components of mucus. 3. Such a cell is already differentiated a performs a specific job. It will not be dividing any more by mitosis.
What is a goblet cell?
1. An antibody (immunoglobulin) is a protein that has a number of identifiable regions within its structure. 2. The variable regions (see below) allow antigen recognition and thus binding to the antigen. 3. Remember back to the idea of splicing and post transcriptional modification - by changing which exons are sliced together in a particular B cell/lymphocyte, the cell can produce a number of different antibody types each of which will recognise a particular antigen because they have different variable regions. 4. The constant region allows it to aid the destruction of the pathogen by a number of means outlined below.
What is an antibody (immunglobulin)?
a toxin or other foreign substance that induces an immune response in the body, especially the production of antibodies.
What is an antigen?
1. When the atria contract, atrioventricular (AV) valves open 2. Blood flows from the atria and into the ventricles 3. When the ventricles contract, the AV valves close and semilunar valves open 4. This forces blood out of the ventricles and into the arteries 5. As arterial pressure rises, the semilunar valves close, ensuring the one-way flow of blood
The heart valves maintain the one-way flow of blood:
a pulse of electricity which travels across the wall of the heart (firstly the atria and then the ventricles) and results in cardiac muscle contraction.
The heartbeat is controlled by a group of specialised muscle cells in the wall of the right atrium called the pacemaker or the sinoatrial node. This can generate
hepatic portal vein
The hepatic portal vein connecting the capillary bed of the intestines with the capillary bed of the liver. This allows amino acids and glucose (and other nutrients) to be absorbed from the small intestine and delivered first to the liver for processing before being transported throughout the circulatory system.
What does this image show?
The image below serves as revision of the link between the hypothalamus and the pituitary. This will not examined in the 2022 Exam. The posterior pituitary releases ADH, a hormone that controls water levels in the blood and hence maintains the osmotic balance in mammals.
What does this image show?
The image below shows the opening of the oviduct/fallopian tube. A mucus plug forms inside the cervix to protect the baby from bacteria during pregnancy
What does this diagram show?
The image shows the changes in the lining of the womb/the endometrium during the menstrual cycle. Note the increase in blood vessels and in glands (tube like structures) that secrete substances to firstly increase and then maintain the lining of the womb. Note ovulation around day 14
antibodies which can attach to any free-floating pathogens e.g. viral particles that have left a cell and are about to enter a new cell.
The immune system is made up of many types of cells which each play a role in the defeat of a pathogen. For our purposes the B cells produce
Bile
The liver produces a fluid called bile which is stored and concentrated within the gall bladder prior to release into the intestine.
What is homeostasis?
The maintenance of body temperature within a narrow range is an example of homeostasis. homeo means like and stasis means steady so the term translates as in a steady state.
Mnemonic: A Goddess Age - Blood vessels become less flexible with advancing age Genetics - Having hypertension predispose individuals to developing CHD Obesity - Being overweight places an additional strain on the heart Diseases - Certain diseases increase the risk of CHD (e.g. diabetes) Diet - Diets rich in saturated fats, salts and alcohol increases the risk Exercise - Sedentary lifestyles increase the risk of developing CHD Sex - Males are at a greater risk due to lower oestrogen levels Smoking - Nicotine causes vasoconstriction, raising blood pressure
There are several risk factors for coronary heart disease (CHD), including:
1. Platelets undergo a structural change when activated to form a sticky plug at the damaged region (primary haemostasis) 2. Fibrin strands form an insoluble mesh of fibres that trap blood cells at the site of damage (secondary haemostasis)
There are two key components of a blood clot -
Compared to normal people, would people with emphysema have more or less air in the lungs after they exhale?
There is more air in the lungs, but they can't get it out. Higher volumes of air in their lungs after they exhale, which leaves very little room for fresh, new air.
(right side of heart)
There is therefore a separate circulation for the lungs
How is Thyroxin unusual?
This hormone is also unusual as almost all cells in the body are targets.
Explain the process of muscle contraction. [8 marks]
a. muscle fibre contains many myofibrils b. made up of sarcomeres/labelled diagram showing one or more sarcomeres c. nerve impulse/signal from (motor) neuron causes release of calcium (ions)/Ca2+ d. calcium (ions)/Ca2+ released from sarcoplasmic reticulum e. calcium (ions)/Ca2+ link to troponin f. tropomyosin moves to expose actin binding sites g. ATP hydrolysis/ATP to ADP and phosphate/release of phosphate from ATP h. ATP binds to myosin heads and causes them to cock/change angle/release/gain energy i. myosin heads bind/form cross-bridges to actin j. myosin heads push on actin and then detach from actin k. actin moved towards centre of sarcomere/sliding of filaments l. sarcomere becomes shorter (resulting in muscle contraction) Accept any mark point if clearly made on an annotated diagram.
Describe the functions of valves in the mammalian heart. [4 marks]
a. prevents backflow/ensures one-way flow/controls direction of flow ✔ b. open valves allow blood to flow throughORopening and closing of valves controls timing of blood flow «during cardiac cycle» ✔c. closed «semilunar» valves allow ventricles/chambers to fill with bloodORclosed «semilunar» valves allow pressure in ventricles to rise «rapidly» ✔d. valves open when pressure is higher upstream/OWTTE/converse for closed valves ✔e. AV/bicuspid/tricuspid/mitral valves prevent backflow from ventricle to atriumORAV/bicuspid/tricuspid/mitral valves open when pressure in atrium is higher «than in the ventricle»/when atrium is pumping/contracting ✔f. semilunar/aortic/pulmonary valves prevent backflow from artery to ventricleORsemilunar/aortic/pulmonary valves open when pressure in ventricle is higher «than in the artery»/when ventricle is pumping/contracting ✔Allow mpa, mpb, mpc or mpd if the point is made through the example of one specific valve.
The process of taking substances into cells and the blood is called:
absorption.
Muscle contraction is a chemical process involving proteins. Explain how skeletal muscle contracts.[8]
actin and myosin filaments are the proteins involved in muscle contraction; (a motor neuron stimulates the) release of calcium ions;from the sacroplasmic reticulum;calcium reveals the binding sites on actin;(no further credit awarded forreference to troponin/tropomysin as they are not on the syllabus)myosin heads form cross-bridges with binding sites on actin;ATP binds to myosin heads;breaking cross bridges to actin;ATP hydrolyzed to ADP (+phosphate);causing myosin heads to change angle/become cocked with energy from ATP;myosin heads bind to new sites on actin further from centre of sarcomere;ADP is released;actin filaments slide inwards to centre of sarcomere/power stroke;[8 max]
Explain the role of antibody production and the principle of vaccination in immunity. [8]
antibody production: exposure to antigen;leads to activation of (helper) T-cells;leads to clonal selection/activation of specific type of B cell;production of plasma cells;specific antibody produced;memory cells produced which provide long lasting immunity;principle of vaccination: artificial exposure to antigen / artificial active immunity;use dead / attenuated pathogen / protein material;first vaccination produces lymphocytes specific to antigen;booster shot causes more intense response/graph to show this;immunity to disease before actually contracting the disease; [8 max]
mineral/ions/element required to move cortical granules to the membrane of the ovum
calcium
Outline how skeletal muscle contracts. [5]
calcium ions are released from the sarcoplasmic reticulum;they expose the myosin binding sites (on actin) / cause movement of blockingmolecules/troponin;cross-bridges form between actin and myosin molecules;ATP provides energy;for actin filaments to slide over the myosin filaments / for myosin to push actin;ATP provides energy to release myosin from binding site;action can be repeated further along the molecule; [5 max]
Explain how a muscle fibre contracts, following depolarization of its plasma membrane. [6]
calcium released from sarcoplasmic reticulum;calcium binds to troponin;troponin with calcium bound makes tropomyosin move;movement of tropomyosin exposes binding sites (for myosin) on actin;contraction of muscle fibres is due to the sliding of filaments (over each other);myosin heads bind to / form cross bridges with actin;ATP binds to the myosin heads causing them to detach from the binding sites;hydrolysis of ATP / conversion of ATP to ADP causes myosin heads to move;myosin heads reattach to actin further along;myosin pushes actin / actin pushed towards the centre of the sarcomere / shortening ofsarcomere; [6 max]
Histamine is also released by a type of white blood cell
called a basophil.
Liver makes
bile
The liquid portion of blood is called
blood plasma (soluble and water-based, because it has a lot of OH that is polar and hence will solve nutrients such as glucose).
term used to describe the "neck of the womb". Needs to dilate during birth.
cervix
The unequal distribution of ions on different sides of the membrane creates a
charge difference called a membrane potential
The image shows a transverse section of an intestinal wall at 100 x magnification.[2 marks] Identify the tissues labelled I and II on the image. I: ..................................................................... II: .....................................................................
circular muscles and longitudinal muscles; muscle; (mentioned in both)
Structure of muscle fibres:
1. Skeletal muscle has a striped appearance and is described as being striated. 2. Embryonic muscle cells fuse together to form large multi nucleated muscle fibres. 3. They are much longer than typical cells and can be up to 4cm in length. 4. Just like any other animal cell, each muscle fibre is surrounded by a plasma membrane. It is called sarcolemma. 5. Within each muscle fibre there are many (up to 2000) myofibrils ("myo" means "muscle"). 6. These structures are made up of proteins. They are elongated parallel structures and characterised by having repeating light and dark bands. 7. Numerous mitochondria are visible between the myofibrils. The myofibrils are surrounded by extensive endoplasmic reticulum called sarcoplasmic reticulum, "sarco" comes from the Greek for "flesh/meat" and muscle are meat.
What systems in our body are needed to get glucose to our cells?
1. The Digestive System 2. The Circulatory System
Ovary
1. The ovary contains follicles in various stages of development 2. These follicles will develop over the course of a menstrual cycle and hence will not always be apparent upon inspection 3. Primordial follicles contain egg cells that have been arrested in prophase I (primary oocytes) 4. Some of these follicles will develop each month into primary follicles and then secondary follicles 5. Each cycle, one follicle will become a dominant Graafian follicle and rupture to release the secondary oocyte 6. The ruptured follicle will then develop into a short-lived corpus luteum, which secretes key ovarian hormones 7. Eventually the corpus luteum will degenerate to form a corpus albicans
Blood composition in Renal artery vs Renal Vein, Urine tests
1. The proper functioning of the kidney ensures that the composition of blood in the renal artery is different from that in the renal vein. 2. The table is taken from your study guide and summarizes these differences. 3. Composition differences between blood in the glomerulus and the filtrate at various points - a likely understanding type structured question!! REMEMBER!!!!
The male and female gametes produce different hormones to promote further development of sex characteristics:
1. The testes produce testosterone to promote the further development of male sex characteristics 2. The ovaries will produce estrogen and progesterone to promote the development of female sex characteristics
The function of arteries is to convey blood at high pressure from the heart ventricles to the tissues of the body and lungs. To this end, arteries have a specialised structure in order to accomplish this task (3):
1. They have a narrow lumen (relative to wall thickness) to maintain a high blood pressure (~ 80 - 120 mmHg). 2. They have a thick wall containing an outer layer of collagen to prevent the artery from rupturing under the high pressure. 3. The arterial wall also contains an inner layer of muscle and elastic fibres to help maintain pulse flow (it can contract and stretch).
Recall the structure indicated by the blue arrow. AND Explain its function.
1. This is the rib cage. 2. It functions in protecting vital organs and blood vessels. 3. It expands and contracts along with the lungs to allow for efficient breathing.
Type I pneumocytes
1. Type I pneumocytes are extremely thin alveolar cells that are adapted to carry out gas exchange. 2. Their thickness is about 0.15 um of cytoplasm. 3. The adjacent capillary wall cells are also a single layer of thin cells. 4. The total distance between oxygen in the alveoli and the capillary is approx 0.5um and this short diffusion distance allows for rapid diffusion.
The primary role of thyroxin is to increase the basal metabolic rate - What is this and how is it achieved?
1. the basal metabolic rate is the amount of energy the body uses at rest. 2. This can be achieved by stimulating carbohydrate and lipid metabolism via the oxidation of glucose and fatty acids
What do you use to send signals across synapses?
A neurotransmitter
Wall Layers
A: 3 V: 3 C: One
Pressure
A: High V:low C: low
Valves
A: No V: yes C: no
increased frequency of heartbeat.
Adrenaline/Epinephrine can act on the SAN which causes _____.
Data Based Q's: Polio incidence in 2012 This figure provides data about polio incidence in the three countries where wild polio was endemic as of mid-2012. Identify the three countries where polio was still endemic as of mid-2012 (1)
Afghanistan, Pakistan and Nigeria.
Mixture of gases that is a poor conductor of heat
Air
What type of molecule is this?
Amino acid (Histadine)
Platelets (thrombocytes)
Clotting factors are released from
atrioventricular node
Controls heart rate by slowing down the electric current sent by the SA node before the signal can pass onto the ventricles.
Outermost region of the kidney
Cortex
What is egestion?
Egestion is the getting rid of undigested and unabsorbed 'food' from the gut, in humans it is called faeces from the anus not released from chemical reactions (not excretion).
What do these red lines represent?
Exhaling (because the volume of air in the lungs is decreasing).
External Fertilisation
External fertilisation is seen in amphibians e.g. frogs and in fish.
Type of diffusion involved in transport of water across a membrane
Facilitated
1. High levels of LDL - (a type of transport structure of triglycerides and cholesterol in the body) 2. High levels of blood glucose due to overeating, diabetes, obesity 3. High blood pressure due to smoking, stress 4. Consumption of trans saturated fats
Factors which increase the risk (but do not themselves cause) of atheroma/plaque formation include:
test penicillin on bacterial infections in mice.
Florey and Chain's experiments to
1. HIV (human immunodefciency virus) infects a type of lymphocyte that plays a vital role in antibody production. 2. Over period of years these lymphocytes are gradually destroyed. 3. Without active lymphocytes, antibodies cannot be produced. This condition is called AIDS (acquired immunodefciency syndrome) and, if untreated, leads to death from infections by a variety of pathogens that would normally be controlled easily.
HIV infects what, exactly?
Epinephrine increases the heart rate to prepare for vigorous physical activity (2).
Heart rate can undergo a sustained increase in response to hormonal signaling in order to prepare for vigorous physical activity: 1. The hormone adrenaline (a.k.a. epinephrine) is released from the adrenal glands (located above the kidneys). 2. Adrenaline increases heart rate by activating the same chemical pathways as the neurotransmitter noradrenaline.
1. Mucous membranes are a thinner and softer type of skin that are found lining many areas/cavities of the body e.g. the nasal passages, mouth, trachea, the bronchus and bronchioles, the vagina, the digestive system. 2. These areas of "skin" secrete a protective moist mucus (from mucus producing cells called goblet cells) containing glycoproteins to stop them drying out.
How are mucous membranes used as physical barrier of the skin?
1. When the skeletal muscles contract, they squeeze the vein and cause the blood to flow from the site of compression 2. Veins typically run parallel to arteries, and a similar effect can be caused by the rhythmic arterial bulge created by a pulse
How are skeletal muscles used in blood flow?
1. vaccine injected/ ingested into body; 2. the virus needs protein to pair with cells, hence the vaccine that is injected into the body contains a protein, which could be an antigen (eg. spike protein in coronavirus) from the pathogen = containing killed / weakened pathogen / fragments of pathogen / mRNA / toxins; 3. macrophages ingest antigen and present it on the surface (antigen presenting cells ingest antigen); 4. T-helper cells bind to macrophages; 5. T-helper cells stimulated / activated; 6. antigen binds to B-cells; 7. activated T-helper cells then bind to B-cells; 8. activation of B-cells; 9. which divide / undergo mitosis to form clones of (plasma) cells; 10. B-cells / plasma cells produce antibodies; 11. memory cells produced; 12. second / booster shot sometimes given; 13. stimulates memory cells; 14. more antibodies and faster response / graph to show this; 15. antibodies are specific to antigen;
How are vaccines used to help the immune response? [8 max]
1. The constant region prevents virus particles/pathogens from binding/docking with a host cell 2. The variable region can attach to toxins and prevent toxin entry into cells (remember cholera toxin) 3. Antibodies can result in AGGLUTINATION/clumping of the pathogen preventing there entry into cells. 4. The constant region can attract phagocytes to the region to ingest the bound pathogens - this is called OPSINISATION 5. The constant region can trigger a chain of reactions which direct the assembly of a protein channel in the pathogen membrane resulting in bursting of the pathogen as water enters - this is called THE COMPLEMENT SYSTEM.
How do antibodies work?
1. The constant region can prevent viruses from docking with their hosts and hence render them unable to cause infection. 2. The constant region can prevent the toxin from binding with the receptor on the cell like in point 1 above. The variable regions attaches to toxins/toxic chemicals produced by pathogens and the constant region will prevent them from attaching to our cells. 3. Antibodies can result in clumping of the pathogen. This prevents their entry into cells. 4. The constant region can attract phagocytes in order to engulf and digest the pathogen. It makes the pathogen more recognisable to phagocytes. This is called opsonisation. 5. The constant region can direct the assembly of proteins which form a pore in the pathogen membrane and results in the pathogen bursting by osmosis. This is called "The Complement System" as it enhances the ability of the antibodies to destroy the pathogen.
How does the constant region aid in the destruction of pathogens?
4 (2 atria, 2 ventricles)
How many chambers does the heart have?
a final tertiary pacemaker (Bundle of His) may coordinate contractions at a constant rate of roughly 30 - 40 bpm
If both fail,
What is important to note about the oocyte?
It is important that the oocyte has as much cytoplasm as possible as it will need the cytoplasm and the organelles to fuel the fertilised egg. This is why their is unequal cell division during meiosis in oocytes.
"Lub dub" sound
Lub: closing of tricuspid and mitral valves (AV valves); systole Dub: closing of aortic and pulmonic valves (semilunar valves); diastole
A)True
Monoclonal antibodies are derived from a single cloned B cell. A)True B)False
B)diagnosing microbial diseases
Monoclonal antibodies are used for A)antibody replacement in people lacking B cells B)diagnosing microbial diseases C)stem cell research D)cloning tissues
What tells the muscles to contract?
Nerve cells = motorneurons (propagation of an action potential down an axon).
Term used to describe the control of the osmolarity (solute conc) of the body/blood/tissue fluid
Osmoregulation
Define osmoregulation
Osmoregulation is the control of the water balance of the blood, tissue or cytoplasm of a living organism
Organisms whose internal solute concentration remains constant despite changes in external osmolarity
Osmoregulator
What does this graph show?
The graph shows blood plasma concentrations ofmelatonin in the hours after ingesting different doses at time zero.
What does this image show?
The image below shows a pale coloured Islet of Langerhans surrounded by the darker exocrine cells.
What does this image show?
The image below shows a secondary oocyte surrounded by follicular cells.
irregular and uncoordinated contraction of the heart muscle (fibrillation)
The interference of the pacemakers will lead to the
oxygenated blood around the body (systemic circulation)
The left side of the heart pumps
Outline the function of the stomach
The stomach is where protein digestion begins, as it contains gastric glands which secrete digestive juices for chemical digestion creating acid that has a low pH environment (pH~1-2) that denatures proteins, while proteases like pepsin hydrolyse large proteins.
What type of glucose makes up maltose?
Two alpha glucose.
Type of filtration involving the removal of small molecules
Ultrafiltration
Excretory waste from deamination released by the kidney
Urea
a. diaphragm more endurance/stronger/generates more force for more ventilation/inspiration b. right ventricle mass increases to pump more blood c. erythrocyte percentage increases to transport oxygen d. less growth/body mass which reduces oxygen demand Reject "loss of body mass" *The physiological reason is required for each mark*
Using the data presented in this question, explain (requires giving a reason for each effect stated) the effect of hypoxia on the body. [2 marks]
weakened version of the pathogen or just an antigen from the pathogen.
Vaccines usually contains a live but
mechanical devices that permit the flow of blood in one direction only
Valves of the heart
Veins collect blood at low pressure from the tissues of the body and return it to the atria of the heart.
Veins Diagram
back to the heart
Veins carry blood
thin walls with wide lumens and valves
Veins have
they transport blood at low pressure
Veins have thin walls with wide lumens and valves because
1. The skin provides a tough physical barrier against the entry of pathogens. 2. Sebaceous glands (exocrine glands which produce a substance called sebum, Latin for "fat") in the skin secrete and oily waterproof substance called sebum which contains fatty acids which lower the pH and inhibits bacterial and fungal growth. 3. The sebum helps to waterproof the skin and pathogens find it difficult to grow without water. 4. Sweat contains lactic acid which also lowers the pH level. Sweat contains lysozyme ("splitting enzyme") which destroys bacterial cells (Note that some bacteria have adapted to live in this hostile environment but they are largely non pathogenic.).
What does the skin provide for the body?
pressure in aorta rises (left atrium is refilling) => semilunar valve open => ventricle relaxes.
What happens at B?
AV opens => and later it is visible that atrial systole occurs again = cycle repeats.
What happens at D?
Cilia are extensions of the cell membrane with a protein skeleton inside them that can bring about movement .
What is cilia?
1. Pathogen ingested by phagocyte by endocytosis 2. Vesicle containing the pathogen is now in the phagocyte 3. Lysosomes attach to the vesicle 4. Contents of the vesicles i.e hydrolytic enzymes are released 5. Carbohydrates, proteins, DNA, cell walls/cellulose, lipids/ phopholipids etc. of the pathogen are digested and pathogen is neutralised.
What is non-specific ingestion of pathogens by phagocytes?
The constant region can direct the assembly of proteins which form a pore in the pathogen membrane and results in the pathogen bursting by osmosis. This is called "The Complement System" as it enhances the ability of the antibodies to destroy the pathogen.
What is the complement system / complement cascade?
Dead epidermis (upperl-layer of skin) filled with keratin cells
What is the upper-layer of the skin made of?
Mitochondria (to generate ATP).
What organelles would you find a lot in the muscles of a heart?
immune system recognises the antigen, along comes a lymphocyte that corresponds to the antigen of the pathogen and they can no longer enter the cells.
When a pathogen comes along the
1. Every species has unique molecules on the surface of their cells e.g unique protein and glycoproteins protruding from the plasma membrane or perhaps unique carbohydrates or other substances on cell walls. 2. These molecules can generate an immune response in the form of antibody production. Hence they can "generate antibodies" and are called "antigens". 3. Note that our own cells use our antigens to recognise them as our own cells and so not launch an immune reaction against them. Only foreign antigens entering our body will result in an immune responce. 4. Viruses use surface molecules to bind to molecules on the surface of host cells. 5. The image shows antigens on the surface of a virus.
Why does every species have unique molecules on their cell's surface?
Where is SRY located?
Y chromosome
Motor neuron
a neuron that sends an impulse to a muscle or gland, causing the muscle or gland to react
A vaccine is
a weakened or attenuated form of the pathogen that contains antigens but is incapable of triggering disease
Annotate this structure of the small intestine:
a) Mucosa b) Submucosa c) Circular muscle layer d) Longitudinal Muscle layer e) Villi
Annotate this microscopic transverse section (cut across) of the intestinal wall:
a) Submucosa b) blood vessels c) Epithelium
The diagram below shoes the female reproductive system. a) Label the diagram above with the letter U to show the uterus. b) Outline the role of luteinizing hormone (LH) after ovulation.
a) later U marked/labelled on uterus (Accept in lumen or on wall). b) formation of the corpus luteum
Answers:
a) tidal volume (the lung volume being measured at a period of rest) b) E placed on a line that is sloping downward. (any of the red portions). c) increased volume; faster breathing rate. (2 points because of 2 marks). d) 7 breaths in 30sec = 7*2 = 14 breaths per minute. e) 0.9 dm^3 min^-1
DBQ: The glucose tolerance test SOLUTION
a. The diabetic person has the concentration of glucose about 70 mg per 100cm cube higher than that of the normal person. b. When the normal person took less than 2 hours to comeback to the baseline, the diabetic person took more than 5 hours to return to the baseline. c. The maximum glucose level is less than 150 mg per 100 cubic cm and is reached at about 1 hour for the normal person. On the other hand, the maximum glucose level is about 320 mg per 100 cubic cm and is reached after 2 hours and 30 minutes for the diabetic person. d. The glucose level started to decrease before 1 and half an hour for the normal person while glucose level started to fall after 2 and half hours for diabetic person.
Describe the production of hybridoma cells. [3 marks]
a. antigen injected into mouse/mammal/host Accept animal b. B cells/B lymphocytes/plasma cells «obtained/extracted from host» c. fusion «of plasma cell» with myeloma cell/tumour cell d. division «of hybridoma cells» to produce a clone
Outline the digestion, absorption and assimilation of proteins in humans.[6]
a. b. c. d. e. f. g. h. i. j. k. l.m.large molecules (proteins) must be digested into small molecules;a protease/pepsin digests proteins into polypeptides;pepsin works in the stomach / requires an acid/low pH/pH 2 to work; polypeptides are digested by a protease/trypsin into amino acids; trypsin acts in the small intestine / requires a basic pH/pH 8/high pH; amino acids absorbed by diffusion/active transport;absorption occurs in the villus/microvilli of the small intestine; (amino acids absorbed) into capillaries;blood carries amino acids throughout the body;amino acids diffuse into cells/are absorbed by active transport;cells use amino acids to build proteins;assimilation is when amino acids become part of a cell;proteins are synthesized at the ribosomes/ER of the cell;[6 max]
Actin and myosin are two proteins found in muscles. Explain how skeletal muscle contracts, including the interaction of these proteins.[8]
a. b. c. d. e. f. g. h. i. j. k. l.motor neuron stimulates the muscle fibre;calcium ions are released (from sarcoplasmic reticulum);calcium ions bind to troponin;tropomyosin moved / binding sites of actin revealed; ATP binds (to myosin) causing cross-bridges to break;ATP becomes ADP causing myosin heads to change angle/become cocked; (myosin) heads attach to (new) actin sites/form cross-bridge;ADP released;myosin heads move actin filaments toward centre;making sarcomere shorter;calcium ions are reabsorbed (into the sarcoplasmic reticulum);muscle fibre relaxes;[8 max]Award the above points if shown in a clearly drawn, correctly annotated diagram.
Describe the importance of hydrolysis in digestion.
a. b. c. d. e.f. g.digestion is the breakdown of large molecules into small molecules;to allow diffusion / to make food soluble;so foods can be absorbed into the bloodstream/body;so foods can move from bloodstream into cells;small moleculescanbe joined toform theorganism's macromolecules;hydrolysis is aided by enzymes;hydrolysis requires water;(unique) h. polysaccharides(hydrolysed)todisaccharides/monosaccharides/specific example;i. proteins/polypeptides (hydrolysed) to amino acids;j. fats/lipids/triglycerides (hydrolysed) to fatty acids and glycerol;[6 max]
Suggest one reason, other than the interval between hibernation emergence periods, for some infected bats surviving longer than others. [1 mark]
a. differences in body mass OR differences in reserves/stores of food/energy/fat b. bats may be predated during a flight / chance events might affect the date of death c. more effective/stronger immune system/immunity (in some bats) d. more resistance to cold (in some bats) e. larger bats lose heat less rapidly f. infected at a different/later date
Based on the data and your biological knowledge, suggest how the infection could lead to premature death in a bat. [3 marks]
a. energy needed to raise body temperature / lost during temperature spikes b. energy/heat released by/comes from (cell) respiration/metabolism c. food/fat (stores/reserves) used in (cell) respiration/in generating energy/heat/raising body temperature d. bats die/starve if fat/energy/food stores used up e. hibernation conserves food stores/reduces use of energy f. no/little food available/food harder to find (in winter/during hibernation period) g. (more) energy/food used when flying/hunting h. (more) heat loss/hypothermia (in winter/cold weather) i. higher chance of being killed by predators when flying/emerged from hibernation
Explain how enzymes catalyse chemical reactions. [3 marks]
a. enzymes work by forming enzyme-substrate complexes b. binding of substrate«s» to active site «of enzyme» c. «enzyme» changes shape slightly OR puts strains on chemical bonds «of substrate» d. decreases activation energy / increases rate of reaction e. enzymes bind to specific substrates Can show these points in an annotated diagram.
Describe what happens in alveoli. [4]
a. gas exchange b. oxygen diffuses from air to blood and carbon dioxide diffuses from blood to air c. oxygen binds to hemoglobin in red blood cells d. pressure inside/volume of alveoli increases/decreases / air enters/exits alveoli duringinspiration/expiration/ventilation e. blood flow through capillaries / concentration gradients of gases/oxygen/CO2 maintained f. type II pneumocytes secrete fluid/surfactant / secretion of surfactant to prevent sides ofalveolus adhering Accept answer in a clearly annotated diagram.
Using all of the data, predict the effect of WNS on bat populations.[3 marks]
a. higher mortality/more deaths b. shorter life expectancy/premature death/death before reproduction c. extinction/reduction in (size of) of bat populations d. L. cinereus/species of bats not affected by WNS may increase OR L.cinereus/species of bats not affected by WNS may experience less competition e. infection may affect birth rates/fertility f. bats will emerge more from hibernation/in winter g. bats will use up food/energy reserves faster in winter/faster due to (more) interruptions h. bat (populations) develop/evolve greater resistance to WNS
Distinguish between the composition of the blood of the renal artery and the blood of the renal vein. [3]
a. less urea/excretory waste products/creatinine in renal vein Allow answers in atable format. For all these mark points, accept the converse as long as it is clear whether the artery orvein has the higher amount.Answers relating to volume and pressure are not relevant to the question.b. less oxygen in the renal vein c. more carbon dioxide in renal veind. less glucose in renal vein e. concentration of sodium ions/chloride ions/pH at normal level in the renal vein whereas it isvariable in renal artery f. solute concentration/osmolarity/water balance at normal level in the renal vein whereas it isvariable in renal artery
Scientists have hypothesised that bats affected by WNS could be more likely than unaffected bats to emerge from hibernation during the winter. Bats occasionally undergo short interruptions in hibernation accompanied by an increase in body temperature. Scientists used sensors attached to M. lucifugus to monitor the temperature of a group infected with the fungus over the winter months. A second uninfected group was also monitored. The graphs show the results for two typical individuals. Distinguish (give a difference) between the patterns of hibernation of the uninfected and infected bats. [1 mark]
a. more (frequent) interruptions/emergences from hibernation/shorter periods of hibernation/more spikes in temperature (indicating emergence) in infected bats b. more fluctuation in (body) temperature (during hibernation) in infected (than uninfected bats) c. emergences/interruptions become more frequent during the hibernation period in infected bats versus (about) about the same frequency in uninfected
Explain how an impulse passes along the axon of a neuron. [8]
a. resting potential is -70 mV / relatively negative inside in comparison to theoutside;b. Na+/K+ pumps maintain/re-establish (the resting potential);c. more sodium ions outside than inside (when at the resting potential);d. more potassium ions inside than outside (when at the resting potential);e. nerve impulse is an action potential that stimulates a (wave of) depolarizationalong the membrane/axon;f. if neuron is stimulated/threshold potential/-50 mV is reached sodium ionchannels open;g. sodium ions diffuse/move in;h. (Na+ move in) causing depolarization;i. potassium ion channels open / potassium ions diffuse/move out;j. (K+ move out) causing repolarization;k. local currents / description of Na+ ion diffusion between depolarized regionand next region of axon to depolarize; [8 max]Accept any of the above points clearly explained in an annotated diagram.
White-nose syndrome (WNS) is a disease caused by the fungus Geomyces destructans. This kills bats from many species during their winter hibernation Scientists used echolocation to record the number of bat flights over a station in 10 minute sample periods during the summers of 2007 to 2009. The graph shows the mean number of flights and number of recording samples for little brown bats (Myotis lucifugus), a species affected by the fungus, along with those of hoary bats (Lasiurus cinereus), which are not affected. B) Suggest one limitation of this recording method in determining the accurate mean number of individual bats flying.[1 mark]
a. same bat may be recorded more than once b. some bats may not fly over [the recording station] OR only bats flying over the station are recorded c. two bats flying close/together might be recorded as one
Outline how ventilation in humans ensures a supply of oxygen.[4]
a. ventilation is exchange of gases between lungs and air ✔b. during inhalation diaphragm contracts AND lowers ✔c. external intercostal muscles contract, raising ribs upwards and outwards ✔d. increase in volume AND decrease in pressure within thoracic cavity ✔ Both needed.e. air drawn into alveoli bringing fresh supply of oxygen ✔f. oxygen concentration in alveolar sacs is higher than in blood capillaries ✔g. «oxygen concentration gradient» causes oxygen to diffuse out of alveoli into red blood cells incapillaries ✔
If blood sugar drops, then
alpha cells in the Islets of Langerhans secrete glucagon, which stimulates the breakdown of glycogen into glucose in the liver and muscle cells.
At the very end of each bronchiole are bunches of little air sacs (like bunches of grapes) called ______.
alveoli (singular= "alveolus"). The alveoli are the place where gas exchange occurs.
Melatonin secretion by the pineal gland of the brain plays a pivotal role in the control of
circadian rhythms
Active skeletal muscle requires a good supply of oxygen. Outline the mechanism of ventilation in the lungs.
during inhalation:a. external intercostal muscles contract moving rib cage up and out;b. diaphragm contracts becoming lower/flatter;c. increase in volume and decrease in pressure (of thorax);d. air flows into lungs as atmospheric pressure is higher;during exhalation:e. internal intercostal muscles contract so ribs move in and down;f. diaphragm relaxes and returns to domed shape;g. decrease in volume and (therefore) increase in pressure (of thorax);h. air moves out until pressure in lungs falls/is equal to atmospheric pressure;i. abdominal muscles can be used to make a stronger/forced exhalation;[6 max]
Everyone starts off as
female, because the SRY gene kicks off after a couple of weeks (evidence for this are nipples in men).
type of proteins found in the jelly layer surrounded the ovum
glycoprotein
The bronchiole split into small sacs of alveoli, which
inflate during inhalation and deflate during exhalation.
Pinocytosis allows materials to be
ingested en masse and hence takes less time than shuttling via membrane proteins.
The opposite end of the muscle from the anchorage is called the ______.
insertion
Overeating causes
more adipose cells to formed and hence more leptin is produced, suppressing further appetite
Explain how skeletal muscle contracts. [9]
muscles/fibres/myofibrils contain (repeating) units called sarcomeres;muscle/sarcomeres contain actin filaments and myosin filaments;actin fibres are thin and myosin fibres are thick;arriving action potential causes release of 2 Ca ;from sarcoplasmic/endoplasmic reticulum;2 Ca binds to troponin;causing troponin and tropomyosin to move (on actin);exposing binding sites on actin / for myosin;ATP binds to myosin heads releasing them / breaking cross bridges;ATP hydrolysed / split into i ADP P ;ATP/energy causes myosin heads to change shape / swivel / become cocked;myosin heads bind / form cross-bridges to (exposed) actin binding sites;myosin heads swivel / move actin (releasing i ADP P );myosin filaments move actin filaments towards centre of sarcomere;sliding of filaments / actin and myosin shortens the sarcomere; [9 max]
Where is insulin produced?
pancreas
Dendrites
short-branched fiber that convert chemical information from other neurons or receptor cells into electrical signals
Melatonin is the hormone responsible for
synchronising circadian rhythms and regulates the body's sleep schedule
Diploid (2n)
two copies of each chromosome
Females possess _____, while males possess ________.
two copies of the X chromosome (XX), while males possess one X and a shorter Y chromosome (XY)
Refractory period
- the period of time following a nerve impulse before a nerve is able to fire again -the potassium and Na+ return to where they were before (after hyperpolarisation)
Chemical transfer across synapses
- when an action potential reaches the axon terminal, it opens voltage gated calcium channels -Ca2+ ions diffuse into the cell and promote the fusion of vesicles with the cell membrane -neurotransmitters are released from the axon terminal b exocytosis and cross the synaptic cleft -these then bind to specific receptors on the post-synaptic membrane and open ligand gated ion channels
Insulin
-insulin lowers blood glucose levels by increasing glycogen synthesis and storage in the liver and adipose tissues
Lung Cancer
-most deaths of any cancer -they are vital to life -they have a very rich blood supply so the liklihood of metastasis is high -couging, wheezing, blood, respiratory distress, and wieght loss
The Islets of Langerhans
-pits in the pancreas where insulin and glucagon are released
Depolarization
-sudden change in membrane potential -from a negative internal charge to a positive charge -neuron gets a signal from a dendrite, the axon opens up sodium channels -as Na+ ions are more concentrated outside the neuron, the opening of sodium channels causes a passive influx of sodium -changing the charge and making the membrane potential positive
Breathing
-the active movement of respiratory muscles that enables the passage of air into and out of the lungs -the contraction of respiratory muscles changes the volume of the thoracic cavity -when the volume of the thoracic cavity increases, pressure in the thorax decreases -when the volume of the thoracic cavity decreases, pressure in the thorax increases
Coronary Arteries
-the blood vessels that surround the heart and nourish the cardiac tissue to keep the heart working -if they get clotted the region of the heart that is supplied by that artery will die
myogenic
-the contraction of the heart is myogenic -this means that they signal for cardiac compression arises within the heart tissue itself -the signal for a heart beat is initiated by the heart muscle cells not the brain
resting potential
-the difference in charge across a membrane when it isn't firing -typically, the inside of a neuron is more negative relative to the outside (about -70 mV) -this potential is controlled by sodium potassium pump 3 Na+ out for every 2 K+ in -requires ATP
Nodes of Ranvier
-the gaps between the myelin sheath -
Cardiac Cycle
-the series of events that take place in the heart over the duration of a single heart beat -contraction (systole), relaxation (diastole)
Bundle of His
-the tertiary pacemaker -can make heart beat at 30-40 ppm
Capillaries
-their function is to exchange materials between cells in tissues and blood traveling at low pressure (10mmHg) -the branching of arteries into capillaries therefore ensures blood is moving slowly and all cells are located near a blood supply
Expiration
-when the pressure in the chest is greater than the atmospheric pressure, air will move out of the lungs
Systole 3
-when ventricular pressure exceeds blood pressure in the aorta, the aortic valve opens and blood is released into the aorta
How many cells thick is one alveolus?
1 cell thick (which is why it needs a structure to be built on = need to put proteins and things outside of it aka. a basement membrane = a membrane at the base of the cell that gives it a shape - the red = a blood capillary that also sits along the basement membrane. If anything damages the basement membrane you no longer have this pouch, but looks like it has less space and has low surface area & walls are thicker)
How many genes would you find in a sperm cell to make Leptin?
1 out of 23 pairs of 46 chromosomes in total, because every cell in our body has 2 copies of each gene in the cell.
Disease vs. illness
1. A disease is any condition that disturbs the normal functioning of the body (i.e. the body can no longer maintain homeostasis) 2. An illness is a deterioration in the normal state of health of an organism (a disease may cause an illness)
3 ways in which CO2 is transported in blood:
1. A small % dissolves in blood plasma. 2. Some binds to hemoglobin. 3. Most (70%) enters erythrocytes and is converted into hydrogen carbonate which moves into plasma for transport, facilitated by the enzyme carbonic anhydrase.
Enzymes found in pancrease:
1. Amylase 2. Endopeptidase
acetlycholinesterase
1. An enzyme called acetlycholinesterase breaks down the acetylcholine to choline and acetyl groups. 2. The choline is reabsorbed into the presynaptic neuron and combined with an acetyl group to reform acetylcholine.
In Vitro Fertilisation - Implantation
1. Approximately two weeks prior to implantation, the woman begins to take progesterone treatments to develop the endometrium 2. Healthy embryos are selected and transferred into the female uterus (or the uterus of a surrogate) 3. Multiple embryos are transferred to improve chances of successful implantation (hence multiple births are a possible outcome) 4. Roughly two weeks after the procedure, a pregnancy test is taken to determine if the process has been successful
What do obese people constantly produce higher levels of and with what consequences?
1. As obese people are constantly producing higher levels of leptin, their body becomes progressively desensitised to the hormone 2. This means they are more likely to feel hungry, less likely to recognise when they are full and are hence more likely to overeat 3. Leptin resistance also develops with age, increasing the potential for weight gain later in life (e.g. the 'middle-age spread')
Structure of the Bowman's Capsule
1. As the blood moves into the kidney via afferent arterioles it enters a knot-like capillary tuft called a glomerulus 2. This glomerulus is encapsulated by the Bowman's capsule, which is comprised of an inner surface of cells called podocytes 3. Podocytes have cellular extensions called pedicels that wrap around the blood vessels of the glomerulus 4. Between the podocytes and the glomerulus is a glycoprotein matrix called the basement membrane that filters the blood
Explain the roles of the loop of Henle, medulla, collecting duct and ADH (vasopressin) in maintaining the water balance of the blood - Osmoregulation
1. As the collecting duct passes through the medulla as it drains into the ureter, the hypertonic solution of the deep medulla will draw water by osmosis 2. Antidiuretic hormone (ADH or vasopressin) is a hormone released from the posterior pituitary in response to dehydration (detected by hypothalamus) 3. ADH increases the permeability of the collecting duct to water, allowing more water to be reabsorbed by osmosis (via the production of aquaporins) 4. This means less water remains in the filtrate and the urine becomes more concentrated 5. When the individual is suitably rehydrated, ADH levels will decrease and less water will be reabsorbed from the collecting ducts
Purpose of Ventilation
1. Because gas exchange is a passive process, a ventilation system is needed to maintain a concentration gradient in alveoli 2. Oxygen is consumed by cells during cellular respiration and carbon dioxide is produced as a waste product 3. This means O2 is constantly being removed from the alveoli into the bloodstream (and CO2 is continually being released) 4. The lungs function as a ventilation system by continually cycling fresh air into the alveoli from the atmosphere 5. This means O2 levels stay high in alveoli (and diffuse into the blood) and CO2 levels stay low (and diffuse from the blood) 6. The lungs are also structured to have a very large surface area, so as to increase the overall rate of gas exchange
Explain the need for a ventilation system
1. Because gas exchange is a passive process, a ventilation system is needed to maintain a concentration gradient within the alveoli 2. Oxygen is needed by cells to make ATP via aerobic respiration, while carbon dioxide is a waste product of this process and must be removed 3. Therefore, oxygen must diffuse from the lungs into the blood, while carbon dioxide must diffuse from the blood into the lungs 4. This requires a high concentration of oxygen - and a low concentration of carbon dioxide - in the lungs 5. A ventilation system maintains this concentration gradient by continually cycling the air in the lungs with the atmosphere
What do the letters R and S indicate?
1. Because the person is taking out the oxygen in the box. 2. To find the slope R = y and S = x --> y = volume & x = time --> Volume / Time = Rate of Oxygen used up.
If blood sugar rises above homeostatsis (approx. 100mg/l) point then
1. Beta cells in the Islets of Langerhans secrete insulin. 2. This stimulates the uptake of glucose into muscle and the liver cells. 3. This glucose is then converted to the storage carbohydrate glycogen in liver and muscle cells. *Note that insulin is removed from the body by the liver and the kidneys and so must be secreted continuously for some time after the glucose levels rise.
Outline the function of the structures in the human elbow joint:
1. Biceps: Bends the arm (flexor) 2. Triceps: Straightens the arm (extensor) 3. Humerus: Anchors muscle (muscle origin) 4. Radius / Ulna: Acts as forearm levers (muscle insertion) - radius acts as a lever for the biceps, ulna acts as a lever for the triceps 5. Cartilage: Allows easy movement (smooth surface), absorbs shock and distributes load 6. Synovial Fluid: Provides food, oxygen and lubrication to the cartilage 7. Joint Capsule: Seals the joint space and provides passive stability by limiting range of movement
There are four main blood groups defined by the ABO system:
1. Blood group A - has O and A antigens on the red blood cells. 2. Blood group B - has O and B antigens on the red blood cells. 3. Blood group AB - has O, A and B antigens 4. Blood group O - has the O antigen only
The nephron is the functional unit of the kidney, with each nephron being comprised of the following components:
1. Bowman's capsule - first part of the nephron where blood is initially filtered (to form filtrate) 2. Proximal convoluted tubule - folded structure connected to the Bowman's capsule where selective reabsorption occurs 3. Loop of Henle - a selectively permeable loop that descends into the medulla and establishes a salt gradient 4. Distal convoluted tubule - a folded structure connected to the loop of Henle where further selective reabsorption occurs
Liver: protein metabolism (4)
1. Breaks down excess amino acids. 2. Gets rid of the amine group (NH2) through DEAMINATION. 3. Converts amine group to urea, which gets excreted by kidneys. 4. Synthesizes non-essential amino acids through TRANSAMINATION.
Application: Causes and Treatment of Diabetes - What is diabetes?
1. Consistently elevated blood sugar, sugar in the urine - the urine is sweet. This is where diabetes gets it full medical title - Diabetes Mellitus - "diabetes" means a funnel or a siphon and indicates the flow of urine and "mellitus" means sweet 2. Elevated glucose damages tissues due to water loss from cells to the surrounding hypertonic tissue fluid. 3. High body sugar levels leads to high levels of glucose in urine. It is difficult to move water from this concentrated urine solution in the kidney back into the bloodstream and so the body can become dehydrated. 4. A symptom of dehydration is thirst. 5. Lots of water in the urine leads to frequent urination.
Dehydration
1. Dehydration is the loss of water from the body without the loss of solutes. 2. The blood plasma and the tissue fluid therefore becomes hypertonic and so cells loose water to this solution and shrink. 3. Consequences are thirst, a low volume of dark coloured urine, lethargy, raised heart rate, low blood pressure, seizures, brain damage, death.
Exhaling
1. Diaphragm muscles relax, causing the diaphragm to curve upwards and reduce the volume of the thoracic cavity 2. Internal intercostal muscles contract, pulling ribs inwards and downwards (reducing breadth of chest) 3. Abdominal muscles contract and push the diaphragm upwards during forced exhalation 4. Additional muscle groups may help pull the ribs downwards (e.g. quadratas lumborum)
Where does gas exchange happen?
1. During gas exchange oxygen moves from the lungs to the bloodstream. At the same time carbon dioxide passes from the blood to the lungs. 2. This happens in the lungs between the alveoli and a network of tiny blood vessels called capillaries, which are located in the walls of the alveoli
What about the immune system of babies?
1. During the last 3 months of pregnancy, antibodies from the mother are passed to her unborn baby through the placenta. 2. This type of immunity is called passive immunity because the baby has been given antibodies rather than making them itself. 3. But this passive immunity is only short-term, because the baby eventually looses this passive immunity and has to build its own active immune system.
The Menstrual Cycle is controlled by negative and positive feedback mechanisms involving ovarian and pituitary hormones.
1. Each cycle carries a chance of conception. 2. In the first half of the cycle, several follicles begin to develop but only one matures. 3. As the endometrial lining repairs, the follicle develops and is released. 4. In the second half, the endometrium is maintained, but if fertilisation does not take place it breaks down and the cycle starts again.
Note that by altering the concentration of the dialysis fluid you can (only remember one or two):
1. Ensure urea and other wastes are removed - dialysis fluid will have no urea or waste 2. Glucose and amino acid concentrations will be at ideal concentrations so that blood composition is in turn optimal. 3. Remove excess blood potassium and add calcium to the blood - dialysis fluid will have low K and high Ca 4. Have a total solute concentration in the dialysis fluid that allows excess water to be removed from the blood by osmosis 5. Reduce blood acidity by adding hydrogen carbonate ions to the blood. Therefore concentration of HCO3- is high in dialysis fluid
Data Based Q's: Polio incidence in 2012 This figure provides data about polio incidence in the three countries where wild polio was endemic as of mid-2012. Given that in 1988 there were an estimated 350,000 cases of polio globally, discuss the success of the polio eradication programme (5)
1. Eradication programme appears to have led to a significant reduction in the total number of cases. 2. only 650/350,000 = 0.2% of the number of cases have been reported. 3. Worsening in two countries 4. Disease is persistent / eradication has not been achieved.
Egestion vs excretion
1. Excretion = go through chemical processes to get rid of. 2. Egestion = never undergone a chemical reaction. Eg. Cellulose = Pass out as cellulose.
What is the filtrate in the kidneys?
1. Filtrate. 2. The fluid filtered from blood, called filtrate, passes through the nephron, much of the filtrate and its contents are reabsorbed into the body. 3. Reabsorption is a finely tuned process that is altered to maintain homeostasis of blood volume, blood pressure, plasma osmolarity, and blood pH.
What carries oxygen around the body to the cells in the blood?
1. Hemoglobin (made up of four polypeptide chains joined together = contains primary, secondary, tertiary & quaternary structure) is the protein inside red blood cells. 2. It carries oxygen. 3. Red blood cells also remove carbon dioxide from your body, bringing it to the lungs for you to exhale. 4. Red blood cells are made in the bone marrow.
Histamine and its role in allergic responses
1. Histamine is a chemical that is released as part of a normal immune response to an antigen. 2. It is released by cells called mast cells. Mast cells are often found in large numbers in the matrix of collagen and cartilage that supports/connects/binds structures together - called connective tissue. 3. Note the vesicles containing histamine inside the mast cell.
Sex determination
1. Human reproduction involves the fusion of a sperm and an egg. 2. Embryos all initially develop in a similar way. 3. Embryonic gonads are formed that could become either ovaries or testes. 4. The presence or absence of a single gene (SRY) decides which developmental pathway is followed. 5. This gene codes for TDF (testis determining factor),a gene regulation protein. By binding to specific DNA site TDF stimulates the expression of genes for testis development.
What do you call movement from a high concentration to a low concentration?
1. If it's just oxygen = Diffusion 2. (If it is water = Osmosis)
Internal Fertilisation
1. In other species the males passes his sperm into the female body and fertilisation is internal. 2. It is seen in reptiles, birds, mammals. 3. It prevents gametes drying out in terrestrial environments. 4. It allows protection for the embryo inside the female. 5. Fertilisation involves mechanisms to prevent polyspermy.
Exercise will influence ventilation in two main ways:
1. Increase ventilation rate (a greater frequency of breaths allows for a more continuous exchange of gases) 2. Increase tidal volume (increasing the volume of air taken in and out per breath allows for more air in the lungs to be exchanged)
What does the spirometer measure?
1. It can be used to measure breathing volumes and breathing rates. 2. It can also be used to calculate the rate of oxygen used up in respiration.
Selective reabsorption is the second of the three processes by which blood is filtered and urine is formed:
1. It involves the reuptake of useful substances from the filtrate and occurs in the convoluted tubules (proximal and distal) 2. The majority of selective reabsorption occurs in the proximal convoluted tubule, which extends from the Bowman's capsule
The main male reproductive hormone is testosterone, which is secreted by the testes and serves a number of roles:
1. It is responsible for the pre-natal development of male genitalia 2. It is involved in sperm production following the onset of puberty 3. It aids in the development of secondary sex characteristics (including body hair, muscle mass, deepening of voice, etc.) 4. It helps to maintain the male sex drive (libido)
How do kidneys change the composition of blood? (6)
1. Lowered amount of urea. 2. Lowered amount of salt ions (renal vein). 3. Lowered amount of water. 4. Nearly identical amount of glucose. 5. Nearly identical amount of protein (too big). 6. No change in amount of blood cells (too big).
What enzyme will do digestion of maltose and where?
1. Maltase is an immobilised enzyme found along mucous membrane lining (epithelium) the intestinal wall (of the small intestine).
What materials and how are they exchanged across the placenta?
1. Materials exchanged and the means by which it happens are shown. 2. This image has been a past exam question recently. 3. Urea moves by diffusion.
How does melatonin synchronise circadian rhythms and regulate the body's sleep schedule?
1. Melatonin secretion is suppressed by bright light (principally blue wavelengths) and hence levels increase during the night 2. Over a prolonged period, melatonin secretion becomes entrained to anticipate the onset of darkness and the approach of day 3. Melatonin functions to promote activity in nocturnal animals and conversely promotes sleep in diurnal animals (like humans) 4. During sleep, necessary physiological changes occur in body temperature, brain wave activity and hormonal production 5. Melatonin levels naturally decrease with age, leading to changes in sleeping patterns in the elderly
Human Experiments
1. Most humans have naturally high levels of leptin in the bloodstream 2. When linked to leptin activity, most cases of obesity are caused by an unresponsiveness to leptin and not a leptin deficiency 3. Hence, in clinical trials, very few participants experienced significant weight loss in response to leptin injections 4. However, many patients did experience adverse side effects from leptin injections, including skin irritations 5. For these reasons, leptin treatments are not considered to be an effective way of controlling obesity
The process of gametogenesis occurs in the gonads and involves the following steps:
1. Multiple mitotic divisions and cell growth of precursor germ cells 2. Two meiotic divisions (meiosis I and II) to produce haploid daughter cells 3. Differentiation of the haploid daughter cells to produce functional gamete
Mechanism of ventilation in the lungs and the concept of tidal volume:
1. Muscle contractions cause the pressure changes inside the thorax that force air in and out of the lungs to ventilate them. 2. Different muscles are required for inspiration and expiration as muscles can only do work when they contract. 3. The external and internal intercostal muscles work as an antagonistic pair. 4. The diaphragm and the abdominal muscles also work in opposing role. They are also antagonistic - coming for the word antagonise - "to act in opposition to". 5. Tidal volume is the volume of air taken in (or given out) during normal unforced inhalation (or exhalation).
How ventilation maintains O2 and CO2 gradients:
1. O2 is constantly being removed from alveoli in the bloodstream and CO2 is released. 2. O2 levels stay high in alveoli & diffuse into blood, and CO2 levels stay low. 3. Lungs have a large surface area for gas exchange.
2. Actin and Myosin Cross-Bridge Formation
1. On actin, the binding sites for the myosin heads are covered by a blocking complex (troponin and tropomyosin) 2. Calcium ions bind to troponin and reconfigure the complex, exposing the binding sites for the myosin heads 3. The myosin heads then form a cross-bridge with the actin filaments
Kidney dialysis (hemodialysis)
1. Patient's blood is pumped into a device with a large surface area. 2. Blood is surrounded by dialysate. 3. Urea slowly diffuses into dialysate.
List three roles of testosterone in males
1. Pre-natal development of male genitalia 2. Development of secondary sex characteristics 3. Maintenance of sex drive (libido)
Hormonal control of pregnancy
1. Pregnancy: Early in pregnancy the embryo produces hCG hormone. This stimulates the corpus luteum to continue to secrete estrogen and progesterone and so maintain and further develop the endometrium with blood supplies. 2. By about week 12 week of pregnancy the ovary stops producing estrogen and progesterone and the placenta takes over the secretion of estrogen and progesterone until childbirth/labour.
Within each muscle fibre are
cylindrical structures called myofibrils and around these is a specialised type of endoplasmic reticulum. There are also mitochondria between the myofibrils.
Processes in spermatogenesis and oogenesis result in different numbers of gametes with different amounts of
cytoplasm
lymphatic system
1) Digestion of lipids 2) Lymph nodes are also found here which allow cells to produce antibodies (immunoglobulins).
What is a consequence of increasing metabolic activity?
1. A consequence of increasing metabolic activity is the production of heat - hence thyroxin helps to control body temperature 2. Thyroxin is released in response to a decrease in body temperature in order to stimulate heat production 3. Thyroxin is partially composed of iodine and hence a deficiency of iodine in the diet will lead to decreased production of thyroxin
A lever is something that:
1. A lever is something that can change the size/magnitude and/or the direction of a force. 2. When a muscle exerts a force e.g. the bicep, the size of that force can be magnified to allow the hand to lift a heavy object. 3. Different bones, at the joints in your body, can move in different directions and so change the direction of the force.
Kidney diseases are conditions which incapacitate the kidney's ability to filter waste products from the blood:
1. Individuals with kidney diseases will demonstrate a reduced glomerular filtration rate (GFR) 2. If untreated, kidney diseases can lead to kidney failure - which is life threatening
Over-hydration
1. Over-hydration is excessive intake of water so body fluids become hypotonic. 2. Consequences are behavioural changes, confusion, delerium, and blurred vision as nerve function is disrupted. 3. Other symptoms include muscle cramps, nausea and in acute cases seizures, coma and death.
What do some health professionals recommend taking against jet lag?
1. Some health professionals recommend taking melatonin near the sleep time of the new time zone to help recalibrate the body 2. By artificially increasing melatonin levels at the new night time, the body can respond quicker to the new day-night schedule
There are also a large number of mitochondria within these tubule cells, as reabsorption involves active transport:
1. Substances are actively transported across the apical membrane (membrane of tubule cells facing the tubular lumen) 2. Substances then passively diffuse across the basolateral membrane (membrane of tubule cells facing the blood)
Glucose can be hydrolysed to produce
ATP (aerobic cell respiration) or stored in animals as the polysaccharide glycogen.
William Harvey
English physician and scientist who described the circulation of the blood; disproved the work of Galen.
Storage polysaccharide in humans
Glycogen
Treatment used to artificially remove nitrogenous waste from the blood
Hemodialysis
Protein used to reduce blood plasma/tissue fluid sugar level
Insulin
Storage site for excess glucose
Liver
Tubules which remove nitrogenous waste from the hemolymph in insects
Malpighian
Organelles found in abundance in cells lining the proximal convoluted tubule
Mitochondria
Which antigen is present on all red blood cells?
O antigen is present on all red blood cells.
Note that all blood groups have the
O antigen.
slows it down.
One nerve from the medulla speeds up the frequency of the heartbeat while another _______.
Organism whose internal solute concentration changes with the external osmolarity
Osmoconformer
Gland that makes ADH
Pituitary
energy for cardiac muscle contraction.
The blood brought by the coronary arteries brings nutrients. It also brings oxygen for aerobic cell respiration, which provides
right atrium
The heart beat is initiated by a group of specialised muscle cells in the:
1. Lymphocytes (produce antibodies) 2. Phagocytes (eat pathogens)
Types of white blood cells (leukocytes)
immunity but do not cause the disease.
Vaccines contain antigens that trigger
secondary response mediated by memory T and B cells.
Vaccines take advantage of the
semilunar valve closes (2nd heartbeat)
What happens at C?
soma
a cell body containing a nucleus and organelles where essential metabolic processes occur
The small intestine is adapted to be good at:
absorption of nutrients.
Beta cells produce
insulin (BIn)
Meiosis also starts with
interphase
relax =
longer
bones are connected to muscles by
tendons
To inhale:
1. make thorax bigger & move outward. 2. move ribcage up.
Thyroxin deficiency (hypothyroidism), results in:
1. tiredness 2. forgetfulness and depression 3. weight gain 4. feeling cold 5. constipation 6. serious brain impairment in children 7. Goitre
Neuron Structure
-dendrites, axon, soma
Digestion process:
1. Ingestion 2. Digestion 3. Absorption (via bloodstream) 4. Assimilation (= become part of the cells) 5. Egestion (parts that are not absorbed)
Why do species that reproduce by external fertilisation produce more eggs?
1. This method of fertilization is susceptible to environmental influences, such as predators and pH changes 2. Consequently, species that reproduce this way usually release large quantities of gametes to compensate for losses
How many chromosomes would you find in a sperm cell?
23 pairs (from the father)
Calculate the percentage decline in the mean number of M. lucifugus flights for 2009 when compared to 2008. [1 mark]
82 / 82.1 / 82.14 (% decline)
Nutrient stored by liver: glycogen
A polysaccharide of glucose (sometimes called animal starch).
1. Metabolic features that may be targeted by antibiotics include key enzymes, 70S ribosomes and components of the cell wall 2. Because eukaryotic cells do not possess these features, antibiotics will target the pathogenic bacteria and not the infected host 3. Antibiotics may either kill the invading bacteria (bactericidal) or suppress its potential to reproduce (bacteriostatic)
Antibiotics are compounds that kill or inhibit the growth of microbes (specifically bacteria) by targeting prokaryotic metabolism:
blood clotting
Cuts in the skin are sealed by
What is the name of the bond between the two alpha glucose?
Glycosidic bond.
Cells which carry out deamination (the removal of amino groups) in humans
Hepatocytes
Draw a labelled diagram of a human kidney:
Here are some guidelines for drawing and labelling the human kidney. Note that IB will only accept the correct spelling of ureter.
In emphysema:
In emphysema total surface area of alveoli decreases and diffusion distance increases due to smaller number of thicker (less permeable) walled enlarged alveoli.
What effect does it have on FSH and LH?
It supresses them
cancer of white blood cells; when white blood cells (leukocytes) divide uncontrollably.
Leukemia
Region of nephron responsible for ensuring a hypertonic medulla (3 Words)
Loop of Henle
________ was the first IVF baby. She was born in the UK in 1978.
Louise Brown
If I start with starch what would you end up with after amylase?
Maltose (disaccharide)
How many cells will make up the wall of the blood capillary?
Only 1 cell.
Progesterone
Progesterone prepares the uterus during the menstrual cycle for the implantation of an embryo and has important roles in supporting a pregnancy.
External and internal intercostal muscles, and diaphragm and abdominal muscles as examples of
antagonistic muscle action.
When the volume of the thoracic cavity decreases, pressure in the thorax
increases
storage substance in a ovum
lipid
These endopeptidases work optimally in
neutral environments (pH ~ 7) as the pancreas neutralises the acids in the intestine.
The rate of absorption depends on the surface area of:
the epithelium.
Which node acts as the "pacemaker" for the heart?
sinoatrial (SA) node
Absorption occurs principally in the:
small intestine.
Neurons pump
sodium and potassium ions across their membranes to generate a resting potential
Circadian rhythms depend on
cells in the hypothalamus. They are called the supra optic chiasmatic nucleus (SCN). Just remember the acronym.
Humans do not possess an enzyme capable of digesting
cellulose (cellulase) and hence it passes through the body undigested (egested)
Implantation of the blastocyst in the endometrium is essential for the
continuation of pregnancy
Each myofibril is made up of
contractile sarcomeres
An allergen is an
environmental substance that triggers an immune response despite not being intrinsically harmful
structure which stores sperm in the testis
epididymis
Which hormone affects the heart beat?
epinephrine
Enzymes for disaccharide hydrolysis are often immobilised on the
epithelial lining of the small intestine, near channel proteins.
"inner" lining of the womb. Has large numbers of blood vessels.
endometrium
Smaller polypeptide chains enter the small intestine where they are broken down by
endopeptidases released by the pancreas
american spelling of the hormone which increases uterine muscle sensitivity to oxytocin
estrogen
Skeletal muscle consists of
large multinucleate cells called muscle fibres.
The length of time a person is immune to infection following a vaccination depends on how
long the memory cells survive for
When the body is challenged by a foreign pathogen it will respond with both a
non-specific and a specific immune reaction
Air is breathed in through the
nose and mouth.
Blood group AB person will
not react to any blood type and so is called a universal recipient.
Electrical traces are viewed on a piece of equipment called an ______.
oscilloscope.
hormone from the posterior pituitary involved in uterine muscle contraction
oxytocin
Amylase is also secreted by the
pancreas in order to continue carbohydrate digestion within the small intestine.
Air flows down from the nose to enter the _____.
pharynx. This is the soft part at the top of the throat that connects the mouth and nose to the oesophagus (carries food to the stomach).
structure which facilitate the exchange of materials between fetus and mother
placenta
Birth is mediated by
positive feedback involving estrogen and oxytocin
Neurons generate and conduct electrical signals by pumping
positively charged ions (Na+ and K+) across their membrane
Estrogen and progesterone cause
pre-natal development of female reproductive organs and female secondary sexual characteristics during puberty
hCG stimulates the ovary to secrete ______ during early pregnancy
progesterone
Leptin binds to
receptors located within the hypothalamus to inhibit appetite and thereby reduce food intake
When a nerve is just sitting there = not transmitting an impulse =
resting potential
In males, the gametes are produced within the
seminiferous tubules of the testes
cells which nurse and nourish developing sperm cells
sertoli
Gametes are
sex (haploid) cells
contract =
shorter
White-nose syndrome (WNS) is a disease caused by the fungus Geomyces destructans. This kills bats from many species during their winter hibernation Scientists used echolocation to record the number of bat flights over a station in 10 minute sample periods during the summers of 2007 to 2009. The graph shows the mean number of flights and number of recording samples for little brown bats (Myotis lucifugus), a species affected by the fungus, along with those of hoary bats (Lasiurus cinereus), which are not affected. A) Calculate the total number of M. lucifugus flights that were recorded in the summer of 2007 [1 mark]
(32 × 79 =) 2528
Leptin is secreted by cells in
adipose tissue
50%
Data-based Q: 1
Air in (inhale):
High O2, Low CO2
Outline the general organization of the nervous system. [4]
formed of central nervous system;brain and spinal cord;peripheral nervous system divided into voluntary and autonomic nervous systems;autonomic nervous system consists of sympathetic and parasympathetic nervous system;voluntary nervous system has motor and sensory neurons; [4 max]
number of spermatozoa resulting from spermatogenesis
four
Thyroxin's chemical structure is unusual as the thyroxin molecule contains
four atoms of iodine.
Diabetes is treated with
either insulin injections (Type I only) or by carefully monitoring and controlling dietary intake (Type II)
The placenta facilitates the
exchange of materials between mother and fetus.
Here is a typical graph derived from a spirometer. Typical questions would include: 4. Suggest a reason why breathing rate may increase
exercise
The pancreas is an example of an _______ as it secretes enzymes, through a duct, into the lumen of the small intestine. Here they carry out a number of hydrolysis reactions:
exocrine gland
Lipoproteins are released by _____ and enter the lacteal by ________. They will later join the bloodstream.
exocytosis and enter the lacteal by endocytosis.
Emphysema/Chronic Bronchitis
damage to air sac walls causing lack of elasticity
Explain the process of aerobic respiration including oxidative phosphorylation. [8]
glucose converted to pyruvate (two molecules);by glycolysis;pyruvate enters the mitochondria;pyruvate converted to acetyl CoA / ethyl CoA;by oxidative decarboxylation / NADH and CO formed; 2fatty acids / lipids converted to acetyl CoA;acetyl groups enter the Krebs cycle (accept acetyl CoA);FAD / NAD+ accepts hydrogen (from respiratory substrates) to form NADH / FADH ; 2FADH / NADH donates electrons / hydrogen to electron transport chain (reject 2donates H+);electrons release energy as they pass along the chain;oxygen final electron acceptor;production of water;builds up proton gradient / protons pumped across inner membrane;protons flow into matrix of mitochondria through ATPase;ATP produced;produces 36 / 38 ATP (per glucose); [8 max]Accept any appropriate terminology for NAD and FAD.
A small proportion of emphysema cases are due to a
hereditary deficiency in this enzyme inhibitor (antiprotease) due to a gene mutation
Fusion of a tumor cell with an antibody-producing cell creates a
hybridoma cell
Epidemiology can be used to compare
i) the incidence of a disease over time (prior and following vaccination programme implementation) ii) the incidence of a disease in different regions (both with and without vaccination programmes)
If the embryos _______ and continue to grow then the pregnancy that follows is no different from a pregnancy that began by natural conception.
implant
Explain how a nerve impulse is transmitted from a motor neurone to a muscle. [8]
impulse reaches the motor end plates / synaptic knobs;synaptic vesicles contain neurotransmitter / acetylcholine;calcium enters through the presynaptic membrane;calcium causes the vesicles to move to and fuse with the membrane / causes exocytosis;neurotransmitter / acetylcholine released into the synaptic cleft;diffuses across the synaptic cleft to the muscle fibre membrane / postsynapticmembrane;binds to receptor sites;causes depolarisation of the muscle fibre membrane / postsynaptic membrane;by opening sodium gates;threshold of stimulation must be reached / all or nothing effect;enzyme / acetylcholinesterase breaks down the neurotransmitter / acetylcholine;depolarisation causes sarcoplasmic reticulum to release calcium ions;calcium ions cause muscle contraction; [8 max]
This causes the symptoms associated with allergies:
inflammation of tissues, itching, mucus secretion and sneezing. Histamine is also implicated in the formation of allergic rashes and in the dangerous swelling known as anaphylaxis. To lessen the effects of allergic responses, anti-histamine drugs can be used.
Lipid breakdown occurs in the
intestines, beginning with emulsification of fat globules by bile released from the gall bladder
A supply of oxygen is needed for aerobic respiration in mitochondria. Describe thefeaturesofalveoliinhumanlungsthatadaptthemforefficientabsorptionofoxygen.[6]
large surface area from having many alveoli; single/flattened layer of (thin) cells in wall; Reject one-cell membrane/thin membrane.(surrounded by) dense network of capillaries/capillary bed; short distance for gases/oxygen/carbon dioxide to diffuse; moist lining / film of moisture on inside of alveolus; moisture allows oxygen/gases to dissolve;diffusion of oxygen down concentration gradient;[6 max]
A gas exchange surface needs to have a
large surface area, be permeable to oxygen and carbon dioxide, be moist (the gases dissolve in water during the exchange process) and finally be thin to allow for rapid diffusion over a smaller distance.
From the pharynx, air flows into the _____.
larynx. These structures sound the same, so do not get them confused! This is the hollow muscular organ forming an air passage to the lungs. It contains our vocal cords, which we can vibrate as air passes them, allowing us to speak.
Insulin
lowers blood glucose levels by increasing glycogen synthesis and storage in the liver and adipose tissues (simply body fat).
Air is carried to the
lungs to the trachea and bronchi and then to the alveoli in bronchioles
organelles which allow for aerobic respiration in sperm cells
mitochondria
type of cell division which produced identical cells with the same number of chromosomes
mitosis
Spermatogenesis and oogenesis both involve
mitosis, cell growth, two divisions of meiosis and differentiation
When exposed to the actual pathogen, the memory cells trigger a
more potent secondary immune response
Describe the roles of nerves, muscles and bones in producing movement. [6]
motor neurones carry impulses / messages to muscle;nerves / neurones stimulate muscles to contract;neurones control the timing of muscle contraction;muscles provide the force for / cause movement;muscles are attached to bone by tendons;bones act as levers;joints between bones control the range of movement;antagonistic muscles cause opposite movements; [6 max]
Bones and exoskeletons act as levers,
moving in response to muscular contraction
Myelinated nerve transmit nerve impulses ________ than unmyelinated ones.
much faster
Skeletal muscle fibres are
multinucleate and contain specialised endoplasmic reticulum
The Malpighian tubule system in insects and the kidney carry out
osmoregulation and the removal of nitrogenous wastes
Explain how ion movements cause a nerve impulse to pass along a neurone. [8]
sodium ions enter the axon/neuron/nerve fibre;by facilitated diffusion / through (voltage gated) channels;depolarization / inside becomes positive / inside more positive than outside;potassium ions leave the neuron;repolarization / inside becomes negative / outside more positive than inside;depolarization and repolarization is an action potential/nerve impulse;action potential propagated / depolarization of next part of axon is triggered;diffusion of sodium ions to next part of neuron/axon;reference to local currents;voltage gated channels open if threshold level is reached;concentration gradients of Na+ and K+ re-established by active transport;sodium potassium pump/sodium pumped out and potassium pumped in; [8 max]Accept any of the points above if clearly explained in a diagram
Explain how nerve impulses travel along a neuron. [8]
sodium potassium pump establishes resting potential;sodium is pumped out and potassium goes in;stimulation produces an action potential;change in permeability of membrane / depolarized;opening of channels letting sodium ions in;potassium ions go out (down their concentration gradient) / repolarization;potassium channels close and sodium pump starts again / re-establishes restingpotential;the potential difference is −65mV or −70mV ;potassium diffuses back out faster than sodium diffuses back in;depolarization in one area triggers depolarization in neighbouring region;leading to movement along neuron;refractory period is the time of recovery from the action potential / incapable ofproducing a new action potential / unidirectional along neuron; [8 max]
Area where 2 nerve cells come close together:
synapse
Membranes of pre-synaptic and post-synaptic neurons play an important role in transmission of nerve impulses. Explain the principles of synaptic transmission.[8]
synapse is gap between adjacent neurons;(arriving) action potential depolarizes pre-synaptic membrane;opens (voltage-gated) calcium channels in membrane;causes influx of calcium ions;causes synaptic vesicles to fuse with pre-synaptic membrane;vesicles release/exocytose neurotransmitter into the synaptic cleft;neurotransmitter diffuses/moves across synaptic cleft;neurotransmitter binds to receptors on post-synaptic membrane;opens channels allowing sodium ions/potassium ions to diffuse;initiation of action potential/depolarization in post-synaptic membrane;removal/breakdown of neurotransmitter stops effect on post-synaptic membrane;Award any of the above points for a clearly drawn correctly annotated diagram.[8 max]
What happens in meiosis but not mitosis?
synapsis of chromosomes (crossing over). The daughter cells produced by mitosis are identical, whereas the daughter cells produced by meiosis are different because crossing over has occurred. The events that occur in meiosis but not mitosis include homologous chromosomes pairing up, crossing over. After crossing over the sister chromatids of each chromosome are no longer identical.
Agglutination means
that the red blood cells have been clumped together due to the presence of antibodies that bind to the antigen that is present on the red blood cell plasma membrane.
double-blind procedure
researcher and volunteers did not know who was getting the leptin and who was getting the placebo - hence a "double blind" trial
Amylase is used in human digestion. State two sites of production of amylase.[1 mark]
salivary glands in the mouth AND pancreas Both needed.
There are many ______ in myofibrils
sarcomeres
Myofibrils consist of repeating units called
sarcomeres, which have light and dark bands. (The light and dark bands extend across all the myofibrils in a muscle fibre, giving it a striated (striped) appearance. Each sarcomere is able to contract and exert force).
tubules within which sperm are formed in the testis
seminiferous
The mucosa is thrown into folds called:
villi.
Blood carrying glucose and other products of digestion fows though:
villus capillaries to venules in the submucosa of the wall of the small intestine.
Loop of Henle reabsorbs
water = creating a hypertonic (highly concentrated = lots of solute) medulla
Antagonistic means working oppositely -
when the inspiratory muscles contract, the expiratory muscles relax (and vice versa)
Ventilation
the process of bringing fresh air into the lungs and removing stale air is called VENTILATION. Note it is not called RESPIRATION.
Which vessel carries deoxygenated blood?
the pulmonary artery
Action potentials are
the rapid changes in charge across the membrane that occur when a neuron is firing
A nerve impulse is only initiated if
the threshold potential is reached
Thyroxin is secreted by
the thyroid gland in the neck to regulate the metabolic rate and help control body temperature.
Iodine deficiency will cause
the thyroid gland to become enlarged, resulting in a disease known as goitre --> You need iodine to make thyroxin and hence it is cheaper for countries to put iodine in their salt (which already has small amounts of iodine), than caring for people who have become diseased due to iodine deficiency --> brain does not develop properly.
The urine is transported from the kidneys via
the ureter, where it is stored by the bladder prior to excretion
The use in IVF of drugs to suspend the normal secretion of hormones, followed by
the use of artificial doses of hormones to induce superovulation and establish a pregnancy
Agglutination when anti A is added means that
you have the antigen to this antibody present on the surface of your red blood cells.
If you need to remove excess water (tissue fluid is becoming too dilute = too much water), then
you need to leave the water in the filtrate to be removed. If you need to conserve water then you remove it from the filtrate back into the blood stream, vice versa.
"jelly layer" surrounding the ovum (2 words)
zona pellucida
term used to describe the diploid cell formed from fusion of male and female gamete
zygote
Insulin and glucagon are released by
β (beta) and α (alpha) cells of the pancreas to control blood glucose concentration
Here is a typical graph derived from a spirometer. Typical questions would include: 3. Measure the volume of the largest breath this person inhaled
this is indicated by Y. The term vital capacity is not on our syllabus.
The proper name for the windpipe is the _____.
trachea
Vaccines contain antigens that
trigger immunity but do not cause the disease
Histamine is made in
two different types of cells: (1) mast cells (2) basophils
There are two types of alveolar cells - type I pneumocytes and type II pneumocytes:
type I pneumocytes and type II pneumocytes
(b) Describe the process of active transport. [4]
uses / requires energy / ATP;goes against concentration gradient / lower to higher concentration;requires a protein in the cell membrane / pump / carrier protein (reject channel);hydrolysis of ATP / ATP →ADP + phosphate;involves a conformational change in the pump / protein / diagram to show this; [4 max]
Outline the process of immunization.......not specifically on the syllabus but serves as a good review [6]
vaccine is used (to induce immunity artificially);vaccine contains dead / weakened / attenuated forms of the pathogen / bacterium / virus;vaccine is injected / ingested;booster shot may be needed;immunity due to vaccination / immunisation lasts for life / a long period;immunity to a disease is due to presence of the appropriate antibodies / cells that canmake them;active immunity is when the body makes the antibodies itself;natural immunity is caused by exposure to a disease / pathogen / bacterium / virus;antibodies are made in response to antigens / vaccine;memory cells are made in response to antigens / vaccine; [6 max
Antigens of the surface of red blood cells are also called (1) and antibodies in the blood plasma are also called ________.
(1) antigens (2)
antigens are
(1) antigens are foreign molecules on the surface of pathogens (can be glycoproteins or proteins or sugars) that trigger the generation of antibodies. (2) they are also found on the surface of your red blood cells.
Define excretion
Excretion is the removal from the body of the waste products of metabolic activities
Role of the Pancreas
-provides amylase in the small intestine -produces insulin and glucagon which are released into the blood -these hormones regulate the concentration of glucose in the bloodstream
The process of childbirth is called parturition and occurs via positive feedback under hormonal control:
1. Positive feedback involves a response that reinforces the change detected (it functions to amplify the change) 2. In the case of childbirth, fetal growth eventually causes stretching of the uterine walls, which is detected by stretch receptors 3. This triggers the release of hormones (oxytocin) that induce uterine muscles to contract, further reducing space in the womb 4. This causes more stretching and hence more contraction until the origin stimulus (the foetus) is removed (i.e. birth)
The small intestine is composed of four main tissue layers, which are (from outside to centre):
1. Serosa - a protective outer covering composed of a layer of cells reinforced by fibrous connective tissue 2. Muscle layer - outer layer of longitudinal muscle (peristalsis) and inner layer of circular muscle (segmentation) 3. Submucosa - composed of connective tissue separating the muscle layer from the innermost mucosa 4. Mucosa - a highly folded inner layer which absorbs material through its surface epithelium from the intestinal lumen
How many divisions occur in meiosis?
2; meiosis I and meiosis II (x2 PMAT) vs. x1 in Mitosis.
Can you calculate the magnification of the drawing from the scale bar presented?
2cm = 20mm/0.5mm = x40 (magnification)
Blood group B person will react to any blood containing
A antigens: Blood Group A or AB
Muscle and Elastic Fibres
A: Large amounts V: small amounts C: None
Wall Thickness
A: Thick V: thin C: extremely thin one cell thick
Risk Factors for Coronary Heart Disease (A Goddess)
Age-blood vessels become less flexible with age Genetics- Hypertension predispose individuals to developing CHD Obesity-strain on the heart Diseases-diabetes and shit Diet- fat people food, alcohol increases the risk Exercise- be fat get a heart attack Sex-males have a greater risk be Smoking- nicotine causes vasoconstriction, raising blood pressure
What conditions are necessary for air to be exhaled from the lungs?
Air pressure in the alveoli must become greater than the air pressure in the mouth.
away from the heart
Arteries carry blood
the bone marrow.
Blood cells are made in
Explain how people can make milk or spaghetti come out of their nose when they sneeze.
Both the mouth and nose (nasal cavity) are directly connected by the pharynx. Sometimes if you sneeze when you are eating, food will be forced out of your nose.
Comparison of Spermatogenesis and Oogenesis: Which involves FSH and LH?
Both yes - I know that sounds odd but these hormones have roles in men also!!
What are the smallest arteries you have?
Capillaries (need to get blood to every cell in the body = need many capillaries).
external nerve stimulation and are called myogenic ("myo"(muscle) and "genic" (generate).)
Cardiac muscle cells can contract without
Pair of antagonist muscles in digestive system:
Circular & Longitudinal Muscles
1. Arteries have thick walls composed of three distinct layers (tunica) 2. Veins have thin walls but typically have wider lumen (lumen size may vary depending on specific artery or vein) 3. Capillaries are very small and will not be easily detected under the same magnification as arteries and veins
Comparison of Blood Vessel Structure
Which of the following occurs with the exhalation of air from human lungs? a. The residual volume of the lungs decreases. b. The rib cage expands. c. The diaphragm contracts. d. The volume of the thoracic cavity decreases. e. The epiglottis closes.
D
Bohr shift
Drop in pH lowers the affinity of hemoglobin for O2; helps O2 to bind in the lungs (due to low partial pressure of CO2) and dissociate in actively respiring tissue (where partial pressure of CO2 is high).
Fragments of the amylopectin molecule that amylase cannot digest are called:
Fragments of the amylopectin molecule that contain the 1-6 bond that amylase cannot digest are called dextrins.
immortal hybridoma cell
Fusion of a tumour cell with a plasma cell produces an
60kg (units required)
G11 HL Semester 1 Exam Jan 2020 Q:
A
G11 HL Semester 1 Exam Jan 2020 Q:
B
G11 HL Semester 1 Exam Jan 2020 Q:
Name of the collection of capillaries that deliver blood to each nephron
Glomerulus
What sorts of things would you find in the filtrate?
Glucose, amino acids, vitamins, minerals, small proteins (eg. hCG, insulin).
hypertonic
Having a higher concentration of solute than another solution.
high blood pressure, high oxygen concentrations, high blood pH, low CO2.
Heart rate will decrease in response to
low blood pressure, low oxygen concentrations, low blood pH, high CO2.
Heart rate will increase in response to
Two, one to carry that receives blood from the lungs to the cells and another that picks up carbon dioxide and other wastes from the cells.
How many pumps does the heart have?
Annotate this ultrastructure of the muscle fibre:
In the centre of each light band is a disc shaped structure called a Z disc or a Z line. From the German, "Zwischenscheibe" - which means "in between".
Fe is needed for
Iron is needed for the heme group in hemoglobin.
Ventilation rate
Is the number of inhalations or exhalations per minute.
Why is the pancreas an exocrine gland?
It secretes enzymes, through a duct, into the lumen of the small intestine. Here they carry out a number of hydrolysis reactions.
What is this?
Mast cell (producing histamine): Billions of these mast cells in the collagen of your body, which contain histamine filled vesicles (which release their contents via exocytosis).
Middle section of the kidney
Medulla
Type of cell that instructs/causes vasoconstriction of a arteriole near the skin surface (2 Words)
Motorneuron
Neurons involved in movement
Motorneurons (only neuron focused on in this unit)
Why do myelinated nerves transmit nerve impulses much faster?
Myelinated nerves can transmit at up to 100m/s as the impulse jumps from one node of Ranvier to the next. This is called Saltatory conduction.
occlusion
Narrowing: ___________ of the coronary arteries can lead to a heart attack.
All motor neurons use acetylcholine to activate skeletal muscle. Explain the effect of neonicotinoid pesticides in insect synapses in the central nervous system. [3 marks]
Neonicotinoid pesticides are similar to nicotine «chemically» Bind to nicotinic/acetylcholine receptors Not broken down by «acetyl» cholinesterase OR binding is irreversible Prevents/blocks acetylcholine binding Blocks transmission from CNS OR blocks signals going to muscle OR muscle contraction blocked OR causes paralysis Reject slows transmission.
_______ in the SCN control secretion of the hormone melatonin by the pineal gland.
Neurones
What type of membrane makes up the plasma membrane of the motorneuron?
Phospholipid protein (fluid-mosaic model with proteins).
the pores in capillaries and into the tissues.
Phagocytes can move through
From days 0 to 4 FSH (follicle stimulating hormone) secretion increases. i) From where is FSH secreted?
Pituitary gland
Draw a labelled diagram of an alveolus and an adjacent capillary.
Plus show minimum 2 capillaries (1 cell thick) -- + YOU HAVE TO INDICATE DIAMETER!
Mr. O'Hanlon's simpler drawing of an alveolus (plus annotate):
Plus show minimum 2 capillaries (1 cell thick) -- also indicate the diameter.
Pneumocytes (or alveolar cells) are
Pneumocytes (or alveolar cells) are the cells that line the alveoli and comprise of the majority of the inner surface of the lungs
1. Arteries and veins were separate blood networks (except where they connected via invisible pores) 2. Veins were thought to pump natural blood (which was believed to be produced by the liver) 3. Arteries were thought to pump heat (produced by the heart) via the lungs (for cooling - like bellows)
Prior to Harvey's findings, scientists held to the antiquated views of the Greek philosopher Galen, who believed that:
First twisted part of the nephron (3 Words)
Proximal Convoluted Tubule
1. The pulmonary arteries carry low-oxygen blood from the right ventricle of the heart to the lungs. 2. The pulmonary veins carry oxygenated blood from the lungs to the left atrium of the heart.
Pulmonary artery vs Pulmonary vein
What is ovulation? When and how often does it occur? Which hormone brings this event about?
Release of an egg, day 14, monthly, LH (under the influence of oestrogen)
hypotonic solution
Solute concentration is less than that inside the cell; cell gains water = a solution that causes a cell to swell because of osmosis.
While the length of a gestation period does appear to positively correlate with size and development, other factors also exist:
Some mammal species may have similar gestation periods despite having significantly different body masses
How do circular muscles work?
Squeezes by making a smaller circumference.
How do longitudinal muscles work?
Squeezes by shrinking.
What chemical would you have just eaten if it were a plant storage molecule?
Starch (amylose + amylopectin)
B) Ventricles begin to contract: 1. Ventricular pressure exceeds atrial pressure which forces the closure of the AV valve (this is heard as a "lub"=first heartbeat by the stethoscope).
The Cardiac Cycle: What happens at B?
C) Ventricular pressure rises above aortic pressure: 1. this forces the aortic (and pulmonary) valves to open. 2. blood is forced into the aorta, increasing its pressure (but it stays below ventricular pressure for a while) 3. ventricular volume decreases dramatically 4. atrial pressure begins to rise again
The Cardiac Cycle: What happens at C?
In females
The Gametogenesis process is called oogenesis and produce ova (eggs)
Gestation Periods
The average 38 week pregnancy in humans can be positioned on a graph showing the correlation between animal size and the development of the young at birth for other mammals
the rapid conversion of fibrinogen to fibrin by thrombin
The cascade results in
Gas Exchange
The exchange of oxygen and carbon dioxide between the alveoli and bloodstream (via passive diffusion)
sinoatrial node
The heart beat is initiated by a group of specialised muscle cells in the right atrium called the:
Nitrogenous waste found in whales
Urea
Name of the tube connecting the kidney to the bladder
Ureter
Name of nitrogenous waste found in insects (2 Words)
Uric Acid
Liquid that describes a mixture of urea and water
Urine
Narrowing of arterioles near the surface of the skin
Vascoconstriction
mineral ions and vitamins
Villi absorb monomers formed by digestion as well as ______
lymph nodes
Where are lymphocytes produced?
membrane bound sac containing hydrolytic enzymes found in the head of a sperm cell
acrosome
The proximal convoluted tubule selectively reabsorbs useful substances by
active transport
Mineral ions like calcium and iron are absorbed from the lumen into the epithelial cells by:
active transport.
The tiny air sacs in the lungs are known as ____.
alveoli.
Bones and exoskeletons provide
anchorage for muscles and act as levers
Blood Groups
any of the various types of human blood whose antigen characteristics determine compatibility in transfusion. The best known blood groups are A, B, AB and O.
Once you have finished Meiosis 1
halpoid
Glucagon
increases blood glucose levels by limiting the synthesis and storage of glycogen by the liver and adipose tissues
The emulsification of fats
increases the total surface area available for enzyme activity (lipase).
Bones and muscles act together as ________.
levers
Gametes are produced by the process of
meiosis; crossing over
Immunity depends on the persistance (continued existence) of
memory cells
In a typical resting potential, the inside of the neuron is
more negative relative to the outside (approximately -70 mV)
Muscle fibres contain many
myofibrils
The myelination of nerve fibres allows for
saltatory conduction
The maintenance of a resting potential is an active process (i.e. ATP dependent) that is controlled by
sodium-potassium pumps
Protein digestion begins in the
stomach with the release of proteases that function optimally in an acidic pH (e.g. pepsin = pH 2)
function of gallbladder
stores and concentrates bile
The use in IVF of drugs to
suspend the normal secretion of hormones, followed by the use of artificial doses of hormones to induce superovulation and establish a pregnancy
The pancreas and gall bladder (via ______) both secrete substances into the small intestine to aid in digestion.
the bile duct
Skeletal muscle is attached
to bone and causes movement of animal bodies.
What was the volume of the green section?
(1 / 3.5) * 2 = 0.57dm^3
The (1) extends/straightens the tibia while the (2) bends the tibia.
(1) extensor (2) flexor
The respiratory system allows us to take in (1) and remove (2).
(1) oxygen (2) CO2
Evaluate the conclusion that the decline in the population of M. lucifugus is due to infection by the fungus.[2 marks]
(2008 to 2009) M. lucifugus declines more (than L. cinereus) OR (2007 to 2009) M. lucifugus declines whereas L. cinereus increases/fluctuates/did not decline OR more affected than unaffected bats in 2007 and 2008 but more unaffected in 2009 Conclusion not supported other factors could be causing the difference between the species/the decrease in M. lucifugus OR there will be differences between the two bat species apart from WNS infection OR both species decreased from 2008 to 2009
State that the endocrine system consists of glands that release hormones that are transported in the blood:
1. An endocrine gland is a ductless gland in the body that manufactures chemical messengers called hormones and secretes them directly into the blood 2. Hormones act on distant sites (target cells) and tend to control slow, long-term activities such as growth and sexual development
What are insect muscles like?
1. An insects leg uses antagonistic muscles to flex and to straighten/extend. 2. In the legs of crickets there are two large muscles inside the femur (you do not need to remember the name of this part of the leg). 3. The tendons at the far ends of these muscles are attached to opposite (inside or outside) sides of the exoskeleton surrounding the tibia (another leg section - do not remember the name). 4. One of the muscles is the flexor (bends) of the joint between femur and tibia and the other is the extensor (straightens).
Hence, the length of the loop of Henle is positively correlated with the degree of water conservation in animals
1. Animals living in moist environments have short loops of Henle that don't descend deeply into the medulla (cortical nephrons) 2. Animals living in arid environments have long loops of Henle that descend deeply into the medulla (juxtamedullary nephrons)
Many different methods are used to move the products of digestion into the villus epithelial cells. Absorption of glucose:
1. Hydrophilic glucose cannot cross the plasma membrane. 2. Their absorption first involves the action of a sodium potassium pump at the opposite side (non lumen side) of the epithelial cell. 3. Na+ ions are pumped out into the intercellular space. K+ ions move in the opposite direction. 4. There is now low sodium ion conc. inside the epithelial cell. 5. Sodium-glucose co-transporter proteins on the microvilli transfer a glucose and a sodium ion simultaneously from lumen to cytoplasm of the epithelial cell. 6. Although this is facilitated diffusion and thus a passive process it is dependent on the active transport of the last step. 7. Glucose channels on the basal/bottom/far side of the cell move glucose by facilitated diffusion into the inter-cellular/interstitial spaces and onto the capillaries
Many different methods are used to move the products of digestion into the villus epithelial cells. Absorption of triglycerides:
1. Digested to fatty acids and glycerol (sometimes monoglycerides which is glycerol still joined to one fatty acid). 2. Absorbed by simple diffusion as they can pass through the hydrophobic phospholipids in the plasma membrane of the epithelial cells. 3. Fat soluble vitamins can also move into cells by simple diffusion. 4. Once inside the cells, fatty acids and monoglycerides recombine. They are now too large to diffuse out again. 5. These newly formed triglycerides join together with cholesterol and become coated with phospholipids and proteins. They are now called lipoproteins. 6. Lipoproteins can enter the lacteal by endocytosis.
Transmission of infectious diseases can occur via a number of distinct mechanisms:
1. Direct contact - the transfer of pathogens via physical association or the exchange of body fluids 2. Contamination - ingestion of pathogens growing on, or in, edible food sources 3. Airborne - certain pathogens can be transferred in the air via coughing and sneezing 4. Vectors - intermediary organisms that transfer pathogens without developing disease symptoms themselves (eg. mosquitoes).
In Vitro Fertilisation - Down regulation
1. Drugs are used to halt the regular secretion of FSH and LH - this in turn stops the secretion of estrogen and progesterone 2. By arresting the hormonal cycle, doctors can take control of the timing and quantity of egg production by the ovaries 3. The drug treatment usually takes about two weeks and is typically delivered in the form of a nasal spray
Generation of an action potential:
1. During an action potential, ions cross back and forth across the neuron's membrane, causing electrical changes that transmit the nerve impulse. 2. An action potential consist of depolarisation and repolarisation across the plasma membrane of an axon. 3. The term depolarisation means a change in electrical potential across the plasma membrane from negative (-70mV) to a positive potential of approx 30mV. 4. The term repolarisation refers to a change back again from positive inside to negative again (remember originally it was positive on the outside, hence the term repolarisation).
Microscopic structure of the kidney and ultrafiltration:
1. Each kidney is made up of approximately 1 million structural units. Each is called a nephron. 2. "Nephros" is the Greek word for "Kidney". Each nephron is supplied with blood. 3. Blood which has been filtered and chemically altered (if needed) leaves the nephron. You are not expected to be able to draw a nephron but you are expected to be able to annotate it with the role of some of the regions. We will examine these.
What is each myofibril surrounded by?
1. Each myofibril (within a muscle fibre) is surrounded by a specialised type of endoplasmic reticulum called sarcoplasmic reticulum. 2. Its function is to store calcium which is needed in order for muscle contraction in response to nervous stimulation. 3. Actin and myosin protein molecules are arranged in a particular way within a myofibril.
Treatment for Emphysema:
1. Emphysema cannot be cured but symptoms can be alleviated. Treatments include: 2. Administering oxygen enriched air to patients 3. Stopping smoking (may be facilitated by prescription medicines) 4. Teaching patients breathing techniques that reduce breathlessness and improve ability to be able to exercise 5. Surgery to remove damaged lung tissue 6. Lung transplants in severe cases
What type of lung condition is Emphysema?
1. Emphysema is a lung condition whereby the walls of the alveoli lose their elasticity due to damage to the alveolar walls 2. The loss of elasticity results in the abnormal enlargement of the alveoli, leading to a lower total surface area for gas exchange 3. The degradation of the alveolar walls can cause holes to develop and alveoli to merge into huge air spaces (pulmonary bullae)
What is the role of exocrine glands?
1. Enzymes are secreted by the exocrine glands. 2. Exocrine glands are groups of cells that secrete substances through a duct/channel into the lumen of the digestive system. 3. Some exocrine glands secrete substances onto the surface of the skin e.g sweat glands, sebaceous glands.
Gender determination in Females
1. Estrogen and progesterone cause pre-natal development of female reproductive organs and female secondary sexual characteristics during puberty. If there is no SRY gene present because there is no Y chromosome, embryonic gonads (in the absence of TDF) develop as female. The hormones estrogen and progesterone are originally present from the mother's ovaries, then from the placenta, and they promote the development of female reproductive organs. During puberty, these hormones cause secondary sexual characteristics to develop e.g breast development, widening hips, pubic hair etc. This is not on the syllabus but it is interesting to note that the male and female genitals are derived from the same cells in the embryo. So for example the penis is the clitoris, the foreskin is the clitoral hood, the scrotum is the labia major, the testis is the ovary, the penile skin is the labia minor etc.
Estrogen
1. Estrogen causes pre-natal development of female reproductive organs if testosterone is not present. 2. These organs include the oviduct, uterus and vagina. 3. Raised levels of estrogen during puberty cause development of female secondary sexual characteristics, including growth of breasts and pubic hair.
Antigens on Red Blood Cells and implications for transfusions:
1. Every organism has unique molecules on the surface of its cells. These are often proteins or polysaccharides. They are called antigens because they can generate an immune response in the form of antibodies. 2. Our immune system functions on the basis of being able to distinguish between foreign antigens and self antigens. 3. Eg. Antigens on the surface of pollen grains can stimulate an immune response that results in symptoms that we call "hay fever".
Steps involved in inhalation & exhalation:
1. External intercostal muscles contract - rib cage upward and outward 2. Internal intercostal muscles relax 3. Diaphragm contracts from dome to flattened shape 4. Abdominal muscles relax to allow outward expansion of organs from contracting diaphragm. 5. Volume of the thorax increases 6. Pressure in the thorax decreases 7. When atmospheric pressure is greater than pressure in thorax then air rushes into the lungs. The opposite events occur in exhalation.
The role of the proximal convoluted tubule
1. Filtrate that has passed from the glomerular capillaries to the Bowman's capsule is called glomerular filtrate. 2. We produce approx 180 litres a day of filtrate containing 1.5kg of salt and 5.5kg of glucose. 3. Almost all the filtrate is reabsorbed - a healthy individual will typically produce 1.5 litres of water in urine, no glucose in the urine and much much less salt. How?
Methods for collecting evidence on muscle contraction (sliding filaments):
1. Fluorescence is the production of light (often visible) from a substance after it has been illuminated by light of a different wavelength e.g UV light. 2. It has been used to investigate muscle contraction. 3. Early experiments involved the use of fluorescence to investigate the role of calcium in muscle contraction. 4. The jellyfish Aequorea victoria produces a protein that is fluorescent when it binds with calcium ions (and light is shone on it). This protein is called Aequorin. This protein allows you to 'see" Calcium. You could describe it as a calcium activated photoprotein, where "photo" indicates light. 5. The protein was injected in the world's largest barnacle, Balanus nubilis. Its common name is the acorn barnacle. The barnacle was chosen because it has the world's largest muscle fibres. 6. When muscles were stimulated to contract, initially their was a strong fluorescence coinciding with the release of calcium ions from the sarcoplasmic reticulum. 7. This region of fluorescence would be concentrated in the region of overlap between actin and myosin in contracted muscle. When the stimulus was stopped the fluorescence decreased. These experiments showed that calcium played a central role in muscle contraction in response to nervous stimulation. 8. Similar results were seen when using radioactive calcium (45Ca) and autoradiography (means "radiation picture") to visualize the location of the radioactivity. In contracted muscle radioactivity was concentrated in the regions of overlapping actin and myosin. In relaxed muscle this pattern was not visible. 9. In another experiment algal cells were used to show that ATP is necessary for myosin to "walk along" an actin filament and that the velocity of the movement increases as the ATP concentration increases. 10. Researchers attached fluorescent dye to myosin molecules and investigated how myosin can move along actin filaments. 11. When they investigated how the myosin movement velocity changed with ATP concentration they obtained a graph as follows. This shows that there is an ATP dependence in the interaction of myosin with actin.
Key Events in the Menstrual Cycle (1. Follicular Phase)
1. Follicle stimulating hormone (FSH) is secreted from the anterior pituitary and stimulates growth of ovarian follicles 2. The dominant follicle produces estrogen, which inhibits FSH secretion (negative feedback) to prevent other follicles growing 3. Estrogen acts on the uterus to stimulate the thickening of the endometrial layer
Blastocyst Formation
1. Following the fusion of an egg and sperm (fertilization), an influx of Ca2+ into the ova prompts the completion of meiosis II 2. The egg and sperm nuclei combine to form a diploid nuclei and the fertilized cell is now called a zygote 3. The zygote will undergo several mitotic divisions to form a solid ball of cells called a morula 4. As the morula continues to divide, it undergoes differentiation and cavitation (cavity formation) to form a blastocyst 5. A blastocyst is comprised of three distinct sections: 6. An inner cell mass (that will develop into the embryo) 7. A surrounding outer layer called the trophoblast (this will develop into the placenta) 8. A fluid filled cavity called the blastocoele
Basement Membrane: Blood is filtered by a mesh called the basement membrane, which lies between the glomerulus and Bowman's capsule
1. Glomerular blood vessels are fenestrated (have pores) which means blood can freely exit the glomerulus 2. The podocytes of the Bowman's capsule have gaps between their pedicels, allowing for fluid to move freely into the nephron 3. Consequently, the basement membrane functions as the sole filtration barrier within the nephron 4. The basement membrane is size-selective and restricts the passage of blood cells and large proteins 5. Hence when the blood is filtered, the filtrate formed does not contain any blood cells, platelets or plasma proteins
Why was Harvey unlucky in the choice of animal to study?
1. He was unlucky in his choice of animal for study because deer foetuses remain microscopically small for quite a long period of time. 2. The microscope was only developed 17 years after his death.
Kidney Transplant
1. Hemodialysis ensures continued blood filtering, but does not address the underlying issue affecting kidney function 2. The best long-term treatment for kidney failure is a kidney transplant: 3. The transplanted kidney is grafted into the abdomen, with arteries, veins and ureter connected to the recipient's vessels 4. Donors must typically be a close genetic match in order to minimise the potential for graft rejection 5. Donors can survive with one kidney and so may commonly donate the second to relative suffering kidney failure
What is this?
1. Here is a cell from the proximal convoluted tubule. 2. Note the microvilli and the numerous mitochondria. 3. Both are adaptations for extensive uptake of materials from the filtrate back into peritubular capillaries surrounding the nephron (peri - around, tubular - the tubes).
The body needs glucose to make ATP (via cell respiration), however the amount required will fluctuate according to demand:
1. High levels of glucose in the blood can damage cells (creates hypertonicity) and hence glucose levels must be regulated 2. Two antagonistic hormones are responsible for regulating blood glucose concentrations - insulin and glucagon 3. These hormones are released from pancreatic pits (called the islets of Langerhans) and act principally on the liver
How does thyroxin regulate the body's metabolic rate?
1. Higher metabolic rate supports more protein synthesis and growth and it increases the generation o body heat. 2. In addition, thyroxin is implicated in heat generation by shivering (increased skeletal muscle contraction) and by uncoupled cell respiration in brown adipose tissue (BAT). 3. In a person with normal physiology, cooling triggers increased thyroxin secretion by the thyroid gland, which stimulates heat production. 4. Recent research has also suggested that thyroxin causes constriction (vasoconstriction / vasodilatation) of small arterioles that carry blood from the core to the skin, reducing heat loss. 5. Thyroxin thus regulates the metabolic rate and also helps to control body temperature.
Histamine
1. Histamine is a chemical used (and made) by the body as part of its defense strategy (responsible for the symptoms of an allergy). 2. Chemical stored in mast cells AND basophils that triggers dilation and increased permeability of capillaries (causing contraction of smooth muscle and dilation of capillaries). 3. Primary effect is to increase blood flow to the site of a infection AND to increase the ability of materials (eg. proteins = antibodies) and cells (eg. white blood cells = Phagocytes, T-cells) to leave blood capillaries.
How is histamine released?
1. Histamine is released in response to a localised infection e.g. an infection in a skin gland causing a "spot". 2. This causes a dilation of blood vessels and also makes the walls of the blood vessels e.g capillaries, more "leaky" or permeable. 3. This results in the increased flow of the components of the immune system found in the blood to the reaction site. 4. These components will be the phagocytes that engulf and destroy pathogens in a non specific manner - any phagocyte will ingest any pathogen. There will also be the increased antibodies delivered to the site of infection. 3. An allergic reaction is when an excessive amount of histamine is released into the bloodstream, from mast cells and basophils, usually in response that an antigen that is not harmful e.g pollen, bee venom, specific foods like peanuts. 4. Body cells with receptor to histamine respond to give a number of symptoms associated with allergic reaction e.g itching, running nose and eyes (to try and remove the perceived pathogen), skin rashes, mucus production. 5. In serious over reactions airways can narrow as excess mucus is produced in the airways. The tongue, lips and face can swell up (in response to excessive leakage of tissue fluid from blood vessels) and this is described as anaphylactic (means "against" "protection") shock. 6.This needs to be treated immediately with antihistamine drugs. A large dose of adrenaline will also reverse the effects of the histamine.
Key Events in the Menstrual Cycle (4. Menstruation)
1. If fertilisation occurs, the developing embryo will implant in the endometrium and release hormones to sustain the corpus luteum 2. If fertilisation doesn't occur, the corpus luteum eventually degenerates (forming a corpus albicans after ~ 2 weeks) 3. When the corpus luteum degenerates, estrogen and progesteron levels drop and the endometrium can no longer be maintained 4. The endometrial layer is sloughed away and eliminated from the body as menstrual blood (i.e. a woman's period) 5. As estrogen and progesterone levels are too now low to inhibit the anterior pituitary, the cycle can now begin again
ANNOTATE: Structural Arrangement of Skeletal Muscles
1. In the diagram below the orange structure is a muscle fibre. 2. It is in turn composed of many myofibrils which are the blue and pink extension is called a myofibril. 3. There are many myofibrils within a muscle fibre. 4. Myofibrils are made up of protein strands/filaments called Actin and Myosin.
ANSWERS TO ANNOTATE: Structural Arrangement of Skeletal Muscles
1. In the diagram below the orange structure is a muscle fibre. 2. It is in turn composed of many myofibrils which are the blue and pink extension is called a myofibril. 3. There are many myofibrils within a muscle fibre. 4. Myofibrils are made up of protein strands/filaments called Actin and Myosin.
Type II Diabetes
1. Late slow onset, inability to respond to insulin, deficiency in receptors on muscle and liver cell plasma membranes 2. Correlated with obesity - risk factors sugary and fatty diets, obesity, lack of exercise and genetic factors 3. Treated by changes in diet to small regular meals with low glycemic index - slow release of sugars as they are more difficult to digest e.g whole grain bread, whole fruits e.g apples, whole beans e.g lentils, kidney beans, chickpeas - you dont have to recall examples) 4. High fibre foods - helps to loose weight by making you feel full - obesity linked to diabetes. 5. Weight loss and exercise is strongly recommended
Each muscle fibre has the following specialised features designed to facilitate muscular contraction:
1. Many nuclei (fibres are long and were formed from many muscle cells fusing together, hence the fibres are multinucleated) 2. Large number of mitochondria (muscle contraction requires a lot of ATP) 3. Tubular myofibrils, divided into sections called sarcomeres, and made of two different myofilaments (proteins responsible for contraction) 4. Where thin (actin) and thick (myosin) filaments overlap, a dark band occurs, and this is flanked by light regions containing thin filament only 5. The membrane surrounding a muscle fibre is called the sarcolemma 6. The internal membranous network is called the sacroplasmic reticulum, it is analogous to endoplasmic reticulum but is specialised for muscle contraction (it contains high levels of Ca2+ ions)
Ventilation: How it works
-Oxygen is consumed by cells during cell res and carbon dioxide is waste - this means O2 is constantly being removed from alveoli and into the blood stream - the lungs function as a ventilation system by continually cycling fresh air into the alveoli from the atmoshphere -the o2 levels are high in alveoli and diffuse into blood -Co2 levels stay low and diffuse from the blood -the lungs are also structured to have a very large surface area in order to increase gas echange
How the Heart Pumps
-SA node sends out an electrical impulse that makes the mycardium (heart muscle) contract -this impulse makes the atria contract and stimulates the AV node that is inbetween the atrium and ventricle - the Atrioventricular node sends signals down the septum via a nerve bundle -the bundle of his innervates the purkinjie fibers in the ventricular wall which causes ventricular contraction
Nerve Impulses
-action potentials that move alon the length of an axon as a wave of depolarization -the ion channels that are on the axon are voltage-gated meaning they change in response to membrane potential -because of this, the axon triggers the opening of ion channels in the next segment of the axon -this causes depolarization to spread along axon like a wave
parasympathetic nerve
-aka vagus nerve -releases the neurotransmitter acetylcholine to decrease heart rate
Elastic Fibres
-allow the arterial wall to stretch and expand upon the flow of a pulse through the lumen -the elastic recoil of these fibres returns the wall to its normal size and keeps the pressure maintained -the recoil also helps to push the blood forward
Glucagon
-alpha (a) cells of the pancreas release it -causes an increase in blood glucose concentration -stimulates glycogen breakdown in the liver
pneumocytes
-alveolar cells are the cells that line the alveoli and comprise of the majority of the inner surface of the lungs
Alveolus Structure
-alveoli funciton as the site of gas exchange -very thin epithelial layer (one cell thick) to increase teh capacity for gas exchange with the blood -spherical in shape to maximize surface area - rich capillary network to increase the capacity for gas exchange with the blood - their internal surface is covered with fluid as dissolved gases are better able to diffuse into the bloodstream
Diastole
-as blood exits the ventricle and travels down the aorta, ventricular pressure falls -when ventricular pressure drops below aortic pressure, the aortic valve closes to prevent back flow (second heart sound) -When the ventricular pressure drops below the atrial pressure, the AV valve opens and blood can flow from atria to ventricle -Throughout the cycle, aortic pressure remains quite high as muscle and elastic fibres in the artery wall maintain blood pressure
Flow of Blood
-blood flows at a low pressure in veins -they pass between skeletal muscle groups which facilitate venous blood flow via periodic contractions -when these muscles contract they squeeze the vein and cause the blood to flow from the site of compression -they run parallel to arteries
Systole 1
-blood returning to the heart will flow into the atria and ventricles as the pressure in them is lower - when the ventricles are 70% full, the atria will contract in the atria and forcing blood into ventricles
Facilitated Diffusion
-channel proteins help hydrophilic food molecules pass through the hydrophobic portion of the plasma membrane -channel proteins are often situated near specific membrane bound enzymes in order to create a localized concentration gradient -certain monosaccharides vitamins and minerals are transported by facilitated diffusion monosaccharides
neurotransmitters
-chemical messengers that are released from nuerons and function to transmit signals across the synaptic cleft -Neurotransmitters are released in response to the depolarisation of the axon terminal of a presynaptic neuron -Neurotransmitters bind to receptors on post-synaptic cells and can either trigger (excitatory) or prevent (inhibitory) a response
Pulmonary artery
-connects the right ventricle and sends deoxygenated blood to the lungs
Inspiration muscles
-diaphragm muscles contract causing the diaphragm to faltten and increase the volume of the thoracic cavity -external intercostal muscles contract and that expands the chest -other muscles help pull the ribs up and out
Expiration muscles
-diaphragm muscles relax causing the diaphragm to reduce volume of thoracic cavity -internal intercostal muscles contract pulling ribs in and down reducing the volume of the chest -abs contract and upwards during forced exhalation
Type I diabetes
-early childhood -body doesn't produce enough insulin -caused by the destruction of B-cells -Requires insulin injections
Continous Capillaries
-endothelial cells held together by tight junctions to limit permiablility
Mitochondria
-epithelial cells of intestinal villi will possess large numbers of mitochondria to provide ATP for al the active transport that occurrs -ATP is required for primary active transport, secondary active transport, and pinocytosis
aorta
-extends from the left ventricle and sends oxygenated blood around the body
myelin
-fatty white substance that functions as an insulating layer around the axon - made by glial cells -made by oligodendrocytes in CNS and Schwann cells in PNS -increases the speed of electrical transmissions via saltatory conduction -makes reactions go 100x faster
Pulmonary Vein
-feeds into the left atrium and returns oxygenated blood to the lungs
Vena Cava
-feeds into the right atrium and returns deoxygenated blood from the body
Simple Diffusion
-hydrophobic materials like lipids may pass freely through the hydrophobic portion of the plasma membrane -once absorbed lipids will often pass first into the lacteals reather than be transported through the bloods -triglycerides
type one pneumocytes
-involved in the gas exchange between alveoli and capillaries -they are flattened and extremely thin (.15 um) to minimize diffusion distance for respiration -they connected by occluding junctions which prevent leakage of tissue fluid into the alveolar air space -tpye I pneumocytes are amitotic and unable to replicate however type II cells can differentiate into type I cells if required
Synapses
-junctions between neurons and between neurons and receptor or effector cells -synapses are the physical gaps that separate the neurons from other cells -they transmit information across a synapse by converting electrical signal into a chemical signal
Nerve Singalling
-pacemaker is under autonomic involuntary control from the brain -from the medulla oblongata, the brain stem
Adrenaline/epinephrine
-released from adrenal glands -this increases heart rate by activating the same chemical pathways as the neurotransmitter noradrenaline
sympathetic nerve
-releases the neurotransmitter noradrenaline to increase heart rate
Neurons
-specialized cells that function to transmit electrical impulses within the nervous system
Atherosclerosis
-the hardening and narrowing of arteries due to the deposition of cholesterol -atheromas develop in the arteries and reduce the diameter of the lumen - this restricts blood flow and increases pressure -can damage the arterial wall -this regions is repaired with fibrous tissue which isn't as elastic -the smooth lining is eventually degraded, lesions form called atherosclerotic plaques -if this ruptures then blood clotting is triggered forming a thrombus that restricts blood flow -if this is dislodged then it becomes an embolus and can cause blockage somewhere else
Delays in a heart beat
-the heart pump sequence ensures that there is a delay between atrial and ventricular contractions resulting in two different heart sounds -the delay allows time for the ventricles to fill with blood following atrial contractions so as to maximise blood flow
Endocytosis
-the invagination of the plasma membrane to create an internal vesicle containing extracellular material -vesicle formation requires the breaking and reforming of the cell membrane and therefore requires energy -in the intestines, vesicles commonly form around fluid containing disolved materials (pinocytosis) -pinocytosis allows materials to be ingested en masse and therefor is much faster than protein transport
Emphysema
-the lung condition where the walls of the alveoli lose their elasticity due to damage to the alveolar walls -this makes the alveoli enlarge abnormally which reduces the total surface area for gas exchange -the degradation of the alveolar walls can cause holes to develop and alveoli to merge into huge air spaces -major cause is smoking symptoms: SOB, phlegm production, expansion of the ribcage, cyanosis and an increased susceptibility to chest infections
threshold potential
-the minimum simulus is the level required to open voltage gated ion channels -about -55 mV -nerve impulse go from the dendrite direction to the axon
Action potential
-the rapid changes in charge across the membrane that occur when a neuron is firing -action potentials occur in three main stages: repolarization, and a refractory period
Repolarization
-the restoration of a membrane potential following depolarization -potassium channels open up and potassium leaves making the membrane potential more negative again
type II pneumocytes
-these cells are responsible for the secretion of pulmonary surfactant which reduces surface tension in the alveoli -they are cubic in shape and possess many granules -they are only about 5% percent of the alveolar surface but comprise of 60% of the total cells
Veins Structure
-they have a very wide lumen to maximize blood flow for more effective return -they have a thin wall containing less muscle and elastic fibres as blood is flowing at a very low pressure (5-10 mmHg) -because the pressure is low, veins possess valves to prevent back flow and stop the blood from pooling at the lowest extremities
myelin sheath
-this is what surrounds some axons -the myelin sheath improves the conduction speed of electrical impulses, but require extra space and energy
Veins Function
-to collect the blood from the tissues and convey it at a low pressure to the atria of the heart
Type II diabetes
-usually occurs during adulthood -body doesn't respond to insulin production -caused by the down regulation of insulin receptors -controlled by managing diet and lifestyle
Atrioventricular valves
-valves between the atria and ventricles -the bicuspid valve is on the left side -the tricuspid is on the right side
Semilunar Valves
-valves between ventricles and arteries -the aortic valve on left side, pulmonary valve on right side
Insulin
-when blood glucose levels are high insulin is released - Insulin is released from beta B cells of the pancreas and cause a decrease in blood glucose concentration -it does this by stimulating glycogen synthesis in the liver (glycogenesis) -this causes the liver and adipose tissues to absorb glucose -it also increases the rate of glucose breakdown
Inspiration
-when the pressure in the chest is less than the atmospheric pressure, air moves into the lungs -because air pressure is lower at high altitudes, a greater increase in chest volume is required before a pressure differential is formed
The human intestines function to absorb the products of digestion and have specialised structures to fulfil this function:
1) The small intestine absorbs usable food substances (i.e. nutrients - monosaccharides, amino acids, fatty acids, vitamins, etc.) 2) The large intestine absorbs water and dissolved minerals (i.e. ions) from the indigestible food residues
Efferent vs Afferent
1. 'efferent', exits the nephron. the name comes from "ex" meaning "out" and "ferre" meaning to "carry". so it translates as "to carry out". 2. The blood vessel which carries blood in is called the afferent - coming from "ad" meaning "to" and "ferre" meaning "to carry". 3. Both of these blood vessels are arterioles which means they are small arteries. 4. The efferent one will branch into many capillaries surrounding the nephron before rejoining to form a branch of the renal vein. 5. A cross section of a kidney in a light microscope is shown below. The circular regions are the glomeruli (sing: glomerulus) and the rest of the section shows the cut nephron tubules.
Acetylcholine
1. Acetylcholine is a neurotransmitter made in presynaptic neurons by combining choline, an essential nutrient from the diet, with an acetyl group made during aerobic respiration. (2. The image on the right shows acetycholine molecules inside a vesicle.)
Summary of Muscle Contractions
1. Action potential in a motor neuron triggers the release of Ca2+ ions from the sarcoplasmic reticulum 2. Calcium ions bind to troponin (on actin) and cause tropomyosin to move, exposing binding sites for the myosin heads 3. The actin filaments and myosin heads form a cross-bridge that is broken by ATP 4. ATP hydrolysis causes the myosin heads to swivel and change orientation 5. Swiveled myosin heads bind to the actin filament before returning to their original conformation (releasing ADP + Pi) 6. The repositioning of the myosin heads move the actin filaments towards the centre of the sarcomere 7. The sliding of actin along myosin therefore shortens the sarcomere, causing muscle contraction
The nephron is the functional unit of the kidney and includes:
1. Afferent arteriole: Brings blood to the nephron to be filtered 2. Efferent arteriole: Removes blood from nephron (minus filtered components) 3. Glomerulus: Capillary tuft where filtration occurs 4. Bowman's Capsule: First part of nephron where filtrate is collected 5. Proximal Convoluted Tubule: Where selective reabsorption occurs 6. Loop of Henle: Important for establishing a salt gradient in the medulla 7. Distal Convoluted Tubule: Final site of selective reabsorption 8. Collecting Duct: Feeds into ureter and is where osmoregulation occurs 9. Vasa Recta: Blood network that reabsorbs components from the filtrate
Role of distal convoluted tubule (DCT)
1. After the loop of Henle the filtrate flows into the distal convoluted tubule. We need to know very little about the role of the distal convoluted but remember one from the list below or simply remember that the distal convoluted tubule is involved in the control/adjustment of ion concentrations in the blood. 2. Plays a role in pH regulation of the bloodstream (by either secreting H+ = blood becomes more acidic or absorbing HCO3 - = blood becomes more alkili) 3. Regulates ion concentration of the blood plasma i.e reabsorbs Ca2+, Na+, Cl- and secretes K+
Unmyelinated vs myelinated propagation of action potentials
1. Along unmyelinated neurons, action potentials propagate sequentially along the axon in a continuous wave of depolarisation 2. In myelinated neurons, the action potentials 'hop' between the gaps in the myelin sheath called the nodes of Ranvier 3. This results in an increase in the speed of electrical conduction by a factor of up to 100-fold
The level of development at birth for mammalian infants can be described as either atricial or precocial:
1. Altricial mammals give birth to relatively helpless, undeveloped offspring that need extended rearing 2. Precocial mammals give birth to more developed offspring that are mobile and independent and require minimal rearing 3. Generally, altricial mammals (e.g. marsupials and rodents) require shorter gestation periods than precocial mammals (e.g. ungulates such as cows, pigs and rhinoceroses)
What are alveoli lined with?
1. Alveoli are lined by a layer of liquid in order to create a moist surface conducive to gas exchange with the capillaries 2. It is easier for oxygen to diffuse across the alveolar and capillary membranes when dissolved in liquid 3. While this moist lining assists with gas exchange, it also creates a tendency for the alveoli to collapse and resist inflation 4. Surface tension is the elastic force created by a fluid surface that minimises the surface area (via cohesion of liquid molecules) 5. Type II pneumocytes secrete a liquid known as pulmonary surfactant which reduces the surface tension in alveoli 6. As an alveoli expands with gas intake, the surfactant becomes more spread out across the moist alveolar lining 7. This increases surface tension and slows the rate of expansion, ensuring all alveoli inflate at roughly the same rate
Excretion and type of nitrogenous waste excreted
1. Amino groups derived from excess amino acids and the nitrogenous bases found in DNA are converted into nitrogen containing waste products which are excreted. 2. The amino group is removed initially as ammonia but in some organisms the ammonia is then converted to other forms. 3. The final nitrogenous waste formed depends on the organism and its environment.
What type of nitrogenous waste is Ammonia?
1. Ammonia is highly reactive with other chemicals in the body. 2. It is also highly soluble which produces an alkaline substance. 3. This alkaline substance will alter the internal pH. 4. The high reactivity makes it a highly toxic/poisonous and dangerous compound. 5. Marine and freshwater organisms, as well as amphibian larvae, use urea as their nitrogenous waste because there is ample water to flush the ammonia out of their bodies (after it has diffused through the gills).
How does amylase break down starch?
1. Amylase break alpha 1-4 linkages of amylose to produce maltose. It cannot break the 1-6 bonds of amylopectine (these sections are called dextrins). 2. Epithelial cells of the small intestine contain within their plasma membranes immobilised enzymes like maltase, dextrinase, lactase, sucrase, etc. 3. Maltase and dextrinase will convert maltose and dextrins respectively to glucose.
Explain how skeletal muscles contract:
1. An action potential from a motor neuron triggers the release of Ca2+ ions from the sarcoplasmic reticulum 2. Calcium ions expose the myosin heads by binding to a blocking molecule (troponin complexed with tropomyosin) and causing it to move 3. The myosin heads form a cross-bridge with actin binding sites 4. ATP binds to the myosin heads and breaks the cross-bridge 5. The hydrolysis of ATP causes the myosin heads to change shape and swivel - this moves them towards the next actin binding site 6. The movement of the myosin heads cause the actin filaments to slide over the myosin filaments, shortening the length of the sarcomere 7. Via the repeated hydrolysis of ATP, the skeletal muscle will contract
1. Depolarisation and Calcium Ion Release
1. An action potential from a motor neuron triggers the release of acetylcholine into the motor end plate 2. Acetylcholine initiates depolarisation within the sarcolemma, which is spread through the muscle fibre via T tubules 3. Depolarisation causes the sarcoplasmic reticulum to release stores of calcium ions (Ca2+) 4. Calcium ions play a pivotal role in initiating muscular contractions
What does the propagation of the nerve impulse mean?
1. An action potential in one part of the axon triggers an action potential in the next part. 2. It is due to diffusion of sodium ions between a region with an action potential and the next region that is still at the resting potential.
Control of muscle contraction:
1. When a motor neuron stimulates a striated muscle fibre, calcium ions are released from the sarcoplasmic reticulum inside the fibre. 2. The calcium binds to troponin, a protein that is associated with the actin filaments in muscle. 3. The calcium causes the shape of troponin to change and this causes the movement of tropomyosin, another protein associated with actin, exposing binding sites on actin. (4. Radioactive calcium (Ca) has been used to investigate the control of muscle contraction. For example, using autoradiography it was shown that radioactive calcium is concentrated in the region of overlap between actin and myosin filaments in contracted muscle, but not in relaxed muscle. This is because calcium ions are bound to troponin, allowing cross-bridge formation and sliding of filaments.)
2. Acrosome Reaction
1. When the sperm reaches an egg, the acrosome reaction allows the sperm to break through the surrounding jelly coat 2. The sperm pushes through the follicular cells of the corona radiata and binds to the zona pellucida (jelly coat) 3. The acrosome vesicle fuses with the jelly coat and releases digestive enzymes which soften the glycoprotein matrix 4. The sperm then pushes its way through the softened jelly coat and binds to exposed docking proteins on the egg membrane 5. The membrane of the egg and sperm then fuse and the sperm nucleus (and centriole) enters the egg
Harvey & the discovery of sexual reproduction:
1. William Harvey's discovery of the circulation of blood in the 17th century shows that he was a brilliant research scientist and yet he made little progress in another area that interested him very much: reproduction in humans and other animals. 2. He was taught the "seed and soil" theory of Aristotle, according to which the male produces a seed, which forms an egg when it mixes with menstrual blood. The egg develops into a fetus inside the mother. 3. William Harvey tested Aristotles theory using a natural experiment. Deer are seasonal breeders and only become sexually active during the autumn. 4. Harvey examined the uterus female deer during the mating season by slaughtering and dissecting them. He expected to and eggs developing in the uterus immediately after mating (copulation), but only found signs of anything developing in females two or more months after the start other mating season. 5. He regarded his experiments with deer as proof that Aristotles theory of reproduction was false, which it certainly is. 6. However Harvey concluded that of spring cannot be the result of mating, which is also false. The problem or Harvey was that the gametes, the process of fertilization and early stages of embryo development are too small to see with the naked eye for a hand lens, and effective microscopes were not available when he was working.
Focus on the advantages and disadvantages of these solutions. Treatments for kidney failure (1):
1. Renal dialysis - sometimes called hemodialysis. The term "dialysis" is derived from "dia" - apart and "lysis" - splitting: - meaning to split the urea away from the rest of the blood. 2. Blood is removed from an artery and returned after dialysis to a vein. Not on syllabus: the vein is strengthened by connecting it to the artery as shown below by the "shunt". The extra pressure causes the vein to thicken and become stronger and so is better able to withstand the frequent sessions of dialysis. 3. The procedure takes several hours a few times a week. Therefore it is time consuming and affects ability to work, travel etc. 4. There is also a risk of infection at the site where the needle is inserted into the patient. 5. But it removes urea = life-saving.
Accessory Organs:
1. Salivary Glands • Release saliva to moisten food and contains enzymes (e.g. amylase) to initiate starch breakdown • Salivary glands include the parotid gland, submandibular gland and sublingual gland 2. Pancreas • Produces a broad spectrum of enzymes that are released into the small intestine via the duodenum • Also secretes certain hormones (insulin, glucagon), which regulate blood sugar concentrations 3. Liver • Takes the raw materials absorbed by the small intestine and uses them to make key chemicals • Its role includes detoxification, storage, metabolism, bile production and haemoglobin breakdown 4. Gall Bladder • The gall bladder stores the bile produced by the liver (bile salts are used to emulsify fats) • Bile stored in the gall bladder is released into the small intestine via the common bile duct
What do terrestrial (land) organisms use to excrete nitrogenous waste?
1. Terrestrial organisms will use energy (a disadvantage) to convert ammonia to less toxic urea (less toxicity is an advantage). 2. As urea is less toxic it requires less water to flush it out of the body and hence helps terrestrial animals to conserve water. 3. Terrestrial mammals and marine mammals (beavers, otters, whales) as well as adult amphibians excrete urea. 4. Marine mammals excrete urea due to their evolutionary history as mammals. Note that some sharks and other marine (saltwater) fish excrete urea also.
Outline the way in which a pregnancy can be detected at a very early stage. [4]
1. Test strip dipped into urine; 2. embryo produces HCG; 3. HCG is present in the urine if the woman is pregnant; 4. (monoclonal) antibodies detect / bind to HCG; 5. (monoclonal antibodies have dye attached so) a colour change if the woman is pregnant; [4 max]
Reasons for failure to control the disease:
1. The leptin produced skin irritations, particularly at the site of injection and so only 47 completed the trial. 2. As leptin is broken down quickly in the body, multiple daily injections were needed. Many volunteers objected to multiple injections. 3. The placebo produced an average weight loss of 1.3kg, the highest leptin dose produced an average loss of 7.1kg, BUT with wide variation around the average. Weight was usually regained rapidly. 4. Leptin use in humans was discontinued.
What happens the longer the loop of henle is?
1. The longer the loop of Henle the more water can be reclaimed from the filtrate. 2. Animals adapted to dry habitats will have long loops of Henle and will have thicker medulla regions (to accommodate long loops). 3. A beaver is aquatic organism. A lemming (on the right hand side) lives in polar areas with little available water and humans are intermediate.
Osmoregulation occurs in the medulla of the kidney and involves two key events:
1. The loop of Henle establishes a salt gradient (hypertonicity) in the medulla 2. Anti-diuretic hormone (ADH) regulates the level of water reabsorption in the collecting duct
The role of the loop of Henle and DCT
1. The loop of Henle maintains hypertonic conditions in the medulla region of the kidney. 2. The descending limb is permeable to water but not salt. The ascending limb can use protein pumps to remove salt. 3. The ascending limb is impermeable to water.
Lung cancers are the most common cause of cancer-related death worldwide for two main reasons:
1. The lungs are vital to normal body function and thus the abrogation of their normal function is particularly detrimental to health 2. The lungs possess a very rich blood supply, increasing the likelihood of the cancer spreading (metastasis) to other body regions
4. Sarcomere Shortening
1. The repeated reorientation of the myosin heads drags the actin filaments along the length of the myosin 2. As actin filaments are anchored to Z lines, the dragging of actin pulls the Z lines closer together, shortening the sarcomere 3. As the individual sarcomeres become shorter in length, the muscle fibres as a whole contracts
Key Events in the Menstrual Cycle (3. Luteal Phase)
1. The ruptured follicle develops into a slowly degenerating corpus luteum 2. The corpus luteum secretes high levels of progesterone, as well as lower levels of oestrogen 3. Estrogen and progesterone act on the uterus to thicken the endometrial lining (in preparation for pregnancy) 4. Estrogen and progesterone also inhibit secretion of FSH and LH, preventing any follicles from developing
The sodium-potassium pump:
1. The sodium-potassium pump is a transmembrane protein that actively exchanges sodium and potassium ions (antiport) via facilitated diffusion 2. It expels 3 Na+ ions for every 2 K+ ions admitted (additionally, some K+ ions will then leak back out of the cell) 3. This creates an electrochemical gradient whereby the cell interior is relatively negative compared to the extracellular environment (as there are more positively charged ions outside of the cell and more negatively charged ions inside the cell) 4. The exchange of sodium and potassium ions requires the hydrolysis of ATP (it is an energy-dependent process)
Seminiferous Tubule
1. The testes are composed of seminiferous tubules which produce sperm 2. Each tubule is surrounded by a basement membrane which is lined by germline epithelium 3. The germline epithelium will divide by mitosis to make spermatogonia (which divide by meiosis to make spermatids) 4. The spermatids differentiate into functional spermatozoa, which are then released into the lumen of the tubule 5. These developing spermatozoa are nourished by Sertoli cells, which reside in the tubule lining 6. Outside of the tubules are blood capillaries and interstitial cells (Leydig cells) which produce testosterone
Explain the presence of glucose in the urine of untreated diabetic patients
1. The urine of non-diabetic patients should contain no glucose as it is selectively reabsorbed from the filtrate in the proximal convoluted tubule 2. Diabetics have higher levels of blood glucose due to either a lack of insulin secretion (type I) or insensitivity to insulin secretions (type II) 3. Because of this, not all of the glucose in diabetics is reabsorbed into the blood (protein pumps in tubule wall become saturated) 4. This results in the presence of glucose in the urine of untreated diabetics, which can be detected using test strips
A more realistic spirometer trace: What is happening to the volume of air over time?
1. The volume of air is decreasing overtime in the spirometer, because it is being used up. 2. The slope = oxygen usage / time = rate of oxygen usage 3. The gradient of the spirometer trace is the rate of oxygen usage overtime (y/x = air/time).
What else is at the synovial joints?
1. There are also ligaments which are tough cords of tissue connecting the bones on opposite sides of a joint. 2. They restrict movement and help to prevent dislocation. 3. Ligaments ensure that certain movements can occur at a synovial joint but not others. 4. For example, the elbow allows considerable movement in one plane: bending (flexion) or straightening (extension), but little movement in the other two planes.
The ABO system
1. There are three possible types of antigens (glycoproteins) to have on the surface of erythrocytes. 2. These are antigen A, antigen B and antigen O.
What characterises the Resting Potential of nerve cell (When a nerve cell is not conducting an impulse):
1. There is a unique distribution of ions across the plasma membrane of the axon. 2. Most notably there is a high concentrations of Sodium outside compared to inside and a high concentration of Potassium ions inside compared to outside. 3. This results in an overall positive charge on one side of the membrane and a negative charge on the other side/on the inside. 4. This separation of charge sets up conditions for the neuron to respond and generate an electrical impulse, just like a separation of charge in a battery sets up conditions that allow a battery to provide electricity.
The main female reproductive hormones (secreted by the ovaries) are estrogen and progesterone, which serve several roles:
1. They promote the pre-natal development of the female reproductive organs 2. They are responsible for the development of secondary sex characteristics (including body hair and breast development) 3. They are involved in monthly preparation of egg release following puberty (via the menstrual cycle) 4. Initially, estrogen and progesterone are secreted by the mother's ovaries and then the placenta - until female reproductive organs develop (this occurs in the absence of testosterone)
Animal size and duration of gestation in mammals - What does this graph show?
1. This graph shows the relationship between (adult) body mass and duration of gestation (pregnancy). Note both scales are logarithmic. 2. There is a positive correlation but there are examples of mammal species that have the same length of gestation (on the y axis) but have body masses that differ greatly (look from left to right from a particular gestation time). It is suggested that human gestation times are high compared to other organisms of similar body mass because of the time needed to develop our extensive nervous system including our very large brain.
Hydrostatic Pressure: Ultrafiltration involves blood being forced at high pressure against the basement membrane, optimising filtration
1. This high hydrostatic pressure is created in the glomerulus by having a wide afferent arteriole and a narrow efferent arteriole 2. This means it is easy for blood to enter the glomerulus, but difficult for it to exit - increasing pressure within the glomerulus 3. Additionally, the glomerulus forms extensive narrow branches, which increases the surface area available for filtration 4. The net pressure gradient within the glomerulus forces blood to move into the capsule space (forming filtrate)
What does this diagram show?
1. This is a diagram showing the sequence of events that allow liquid (containing uric acid) to move through the Malphigian tubules into the gut and allows waste to be excreted. 2. Active transport of ions and uric acid from the hemolymph to the lumen of the Malphigian tubule causes water to follow by osmosis and the liquid moves into the hindgut. 3. Selective reabsorption in the hindgut back into the hemolymph, followed by water movement out of the gut, allows for water retention and osmoregulation.
What is this?
1. This is an electron micrograph of a cell found lining the placental villus. 2. Maternal blood will be on one side and a capillary belonging to the fetus will be on the other. 3. Note the microvilli, the abundant mitochondria and the many endocytotic vesicles present in the cell. 4. It is these cells that produce the estrogen and progesterone form the placenta which enters the maternal bloodstream. These cells will also be very thin - why?
Oogenesis
1. This is the creation of an egg cell or an ovum. 2. Oogenesis starts in the ovaries of the female fetus. 3. Cells firstly divide by mitosis and the newly formed cells distribute themselves throughout the outer region of the ovary. 4. When the fetus is 4 or 5 months these cells grow and then begin to divide by meiosis. 5. They stop in the first division of meiosis and become surrounded by a single layer of cells called follicle cells. 6. It is called a primary follicle and it contains a primary oocyte. 7. No further development takes place until the onset of puberty. 8. Each month after puberty a small number of primary follicles are stimulated by FSH and usually just one goes on to become a mature follicle (complete meiosis I and begin meiosis II) with a secondary oocyte enclosed.
Human Chorionic Gonadotropin (hCG)
1. When a blastocyst becomes implanted in the endometrial lining it begins to secrete human chorionic gonadotropin (hCG) 2. hCG promotes the maintenance of the corpus luteum within the ovary and prevents its degeneration 3. As a consequence of this, the corpus luteum survives and continues to produce both oestrogen and progesterone 4. Oestrogen inhibits FSH and LH production by the pituitary gland, preventing the release of more eggs from the ovaries 5. Progesterone also functions to maintain the endometrium (which is nourishing the embryo) and thicken the cervix 6. The levels of hCG are maintained for roughly 8 - 10 weeks while the placenta is being developed 7. After this time, the placenta becomes responsible for progesterone secretion and nourishing the embryo 8. At this point the corpus luteum is no longer required and begins to degenerate as hCG levels drop
How do human changes in ventilation occur?
1. Ventilation in humans changes in response to levels of physical activity, as the body's energy demands are increased 2. ATP production (via cellular respiration) produces carbon dioxide as a waste product (and may consume oxygen aerobically) 3. Changes in blood CO2 levels are detected by chemosensors in the walls of the arteries which send signals to the brainstem 4. As exercise intensity increases, so does the demand for gas exchange, leading to an increase in levels of ventilation
Placenta (you are not expected to be able to draw or label the placenta):
1. Maternal blood flows into "spaces" in the placenta and collects in these areas. (The spaces are called lacunae after the Latin word "lacus" meaning "a lake"). 2. Finger like projections called placental villi extend into this pooled blood. 3. Placental villi have a combined surface area of approx 14m2. 4. Within these villi are numerous fetal capillaries. 5. Exchange of materials takes place over the short distance (5 micrometres) between fetal blood in the capillaries and the pooled maternal blood in the spaces. 6. Maternal blood depleted in nutrients and high in wastes leave the spaces through the maternal venules. 7. Fresh blood from a maternal arteriole will take its place. 8. Note that the umbilical artery flows away from the fetus and so carries deoxygenated blood. 9. The two umbilical veins flow towards the fetus and so carry oxygenated blood.
When does melatonin increase and decrease?
1. Melatonin increases at night when light intensity decreases and decreases at dawn when light intensity begins to increase again. 2. High melatonin increases drowsiness and causes a drop in core body temperature. It may also inhibit urine production at night.
Key Events in the Menstrual Cycle (2. Ovulation)
1. Midway through the cycle (~ day 12), estrogen stimulates the anterior pituitary to secrete hormones (positive feedback) 2. This positive feedback results in a large surge of luteinizing hormone (LH) and a lesser surge of FSH 3. LH causes the dominant follicle to rupture and release an egg (secondary oocyte) - this is called ovulation
The tubules reabsorb all glucose, amino acids, vitamins and hormones, along with most of the mineral ions (~80%) and water:
1. Mineral ions and vitamins are actively transported by protein pumps and carrier proteins respectively 2. Glucose and amino acids are co-transported across the apical membrane with sodium (symport) 3. Water follows the movement of the mineral ions passively via osmosis
spermatogenesis simplified
1. Mitosis 2. Cell growth 3. Meiosis 4. Cell differentiation*** commonmultiplechoicequestionhavetoputinorder.
Analyse electron micrographs to find the state of contraction of muscle fibres
1. Muscle fibres can be fully relaxed, slightly contracted, moderately contracted and fully contracted 2. The sarcomere gets shorter when the muscle contracts, however the A band does not, showing that the filaments are not themselves contracting 3. Instead, the filaments are sliding over each other and increasing their overlap, which can be seen as the gradual reduction in the H zone
Where are tendons?
1. Muscles have tendons at both ends forming attachments with bones or in the case of insects the exoskeleton. 2. At one end the attachment does not move when the muscle contracts. 3. This end is called the anchorage or the origin. 4. In humans bones are used as anchorage. 5. In the case of the upper arm the humerus and the shoulder blade provide anchorage points for the triceps and biceps. 6. In insects and other arthropods the exoskeleton is used for anchorage.
What do muscles do?
1. Muscles provide the forces to move animals bodies. 2. This force is exerted only when a muscle contracts. 3. So the force is exerted in only one direction. 4. For opposite movements you will need two muscles working in opposite directions (antagonistic muscles).
Myelin
1. Myelin is a specialized membrane consisting of proteins and lipids that wrap around axons. 2. You can think of it as the plasma membrane of a Schwann cell. 3. Many Schwann cells form a covering or a sheath along the length of the axon. 4. The gaps between the cells of the sheath are called Nodes of Ranvier
Structures of the Female Reproductive System The female reproductive system includes all the organs responsible for the production of an oocyte (the female gamete) and contribute to the production and maintenance of an egg as part of the female reproductive process It also includes the organs involved in initially developing and maintaining an embryo during the early stages of pregnancy Structures are organised according to the path taken by egg (from production to implantation or elimination)
1. Ovary - The ovary is where oocytes mature prior to release (ovulation) - it also responsible for estrogen and progesterone secretion 2. Fimbria - Fimbria (plural: fimbriae) are a fringe of tissue adjacent to an ovary that sweep an oocyte into the oviduct 3. Oviduct - The oviduct (or fallopian tube) transports the oocyte to the uterus (it moves the egg to the uterus like moving mucus through the trachea, hence by cilia = little hairs in the oviduct that collect it / move it along) - it is also typically where fertilisation occurs 4. Uterus - The uterus is the organ where a fertilised egg will implant and develop (becoming an embryo) 5. Endometrium - The mucous membrane lining of the uterus, it thickens in preparation for implantation or is otherwise lost (via menstruation) 6. Vagina - Passage leading to the uterus by which the penis can enter (uterus protected by a muscular opening called the cervix)
Distinguish between ventilation, gas exchange and cell respiration
1. Ventilation: The exchange of air between the lungs and the atmosphere; it is achieved by the physical act of breathing 2. Gas exchange: The exchange of oxygen and carbon dioxide in the alveoli and the bloodstream; it occurs passively via diffusion 3. Cell Respiration: The release of ATP from organic molecules; it is greatly enhanced by the presence of oxygen (aerobic respiration)
Voluntary vs involuntary muscles
1. Voluntary = under my control (eg. bicep & tricep) 2. Involuntary = not under my control (eg. in the breathing system, digestive system)
Spermatogenesis process
1. Outer layer called germinal epithelium cells divide endlessly by mitosis to produce more diploid cells 2. Diploid cells grow into larger cells with more cytoplasm and become primary spermocytes 3. Each primary spermocyte carries out the first division of meiosis to produce two secondary spermatocytes(thesewouldbehaploid) 4. Each secondary spermatocytes carries out the second division of meiosis to produce two spermatids 5. Spermatids become associated with nurse cells, called Sertoli cells, which help spermatids to develop into spermatozoa. This is cell differentiation. 6. Sperm cells detach from sertoli cells and eventually are carried out of the testis by the fluid in the centre of the seminiferous tubule.
Overhydration
1. Overhydration is a less common occurrence that results when an over-consumption of water makes body fluids hypotonic 2. Individuals will produce excessive quantities of clear urine in an effort to remove water from the body 3. The hypotonic body fluids will cause cells to swell (due to osmotic movement), which can lead to cell lysis and tissue damage 4. Overhydration can lead to headaches and disrupted nerve functions in mild cases (due to swelling of cells) 5. In severe cases, overhydration may lead to blurred vision, delirium, seizures, coma and eventual death
There are two key groups of hormones which control and coordinate the menstrual cycle:
1. Pituitary hormones (FSH and LH) are released from the anterior pituitary gland and act on the ovaries to develop follicles 2. Ovarian hormones (estrogen and progesterone) are released from the ovaries and act on the uterus to prepare for pregnancy
When is melatonin secreted?
1. Receptor cells in the retina detect the presence or absence of light (in the wavelength of 460-480nm (blue region of the spectrum) that pass impulses to the SCN about the timing of dawn and dusk. This in turn adjusts melatonin levels production from the pineal body. This is why you are advised to avoid blue screens on mobile phones and computers during flight or late at night if you want to try and fall asleep.) 2. A message is sent to the SCN which is part of the brain region called the hypothalamus. 3. From here a message is sent to the pineal gland (pineal means "pine" like in a pine cone). 4. Cells in the pineal gland (an endocrine gland) secrete melatonin into the bloodstream.
Some of the symptoms from overproductions of histamine:
1. Red Rash because blood under your skin is red and when blood vessels are leaking blood underneath your skin you get a red rash. 2. Swelling (lots of it) because if your blood capillaries start leaking out too much blood plasma the area begins to swell, so you get swelling (a limited amount of this is good, but this is an overreaction). Eg. Tongue swelling = Block your breathing system.
There are two key functions that an excretory system performs:
1. Removes nitrogenous wastes that may be toxic to the body in large concentrations 2. Removes excess water to maintain a suitable osmolarity within the tissues and cells
Here is a recent exam question for 8 marks that asked: "Explain how insects excrete nitrogenous waste"
1. nitrogenous waste excreted as uric acid ✔ 2. uric acid is non-toxic ✔ 3. conversion to uric acid requires energy/ATP ✔ 4. nitrogenous waste «accumulates» in hemolymph ✔ 5. nitrogenous waste absorbed/taken into by Malpighian tubules ✔ 6. nitrogenous excretion in insects uses Malpighian tubules ✔ 7. active transport of ions/Na+/K+ into Malpighian tubules ✔ 8. water absorbed by osmosis moves uric acid/nitrogenous waste to «hind» gut ✔ 9. ions now actively removed from hind gut back to hemolymph ✔ 10. water follows (by osmosis)/reabsorbed from the feces and returned to hemolymph ✔ 11. uric acid precipitates/becomes solid/forms a paste so can pass out with little water ✔ 12. uric acid excreted/egested with the feces ✔ 13. water conservation/osmoregulation OR reduces mass of water «in body»✔
If I were an oxygen molecule outside and I wanted to get into the hemoglobin in the red blood cell (ethrocyte), how many cell walls would I have to cross?
5 cell walls
Calculate the number of breaths from the first yellow line to the second:
6
How long did it take for them to breath these 6 breaths?
6 breaths in 15sec 2 breaths in 5 secs = 60 / 5 = 12*2 = 24 breaths per minute.
The muscle connects a (1) to a (2)
(1) static bone (point of origin) (2) moving bone (point of insertion)
The mechanical action of the stomach:
(churning) also promotes digestion by mixing the food.
hypertonic
(conc solute/higer osmolarity)
hypotonic
(dilute solute/lower osmolarity) solutions
The process of gametogenesis occurs in the reproductive organs:
(gonads) of the male and female
Both maltose and dextrin are digested by enzymes
(maltase) which are fixed to the epithelial lining of the small intestine.
isotonic
(same osmolarity)
Capillaries have permeable walls that allow exchanges of material between cells in tissues and blood in capillaries.
- Arteries split into arterioles which in turn split into capillaries, decreasing arterial pressure as total vessel volume is increased. - The branching of arteries into capillaries ensures blood is moving slowly and all cells are located near a blood supply. - After material exchange has occurred, capillaries will pool into venules which will, in turn, collate into larger veins.
Heart structure: blood vessels
- Vena cava (inferior and superior) feeds into the right atrium and returns deoxygenated blood from the body. - Pulmonary artery connects to the right ventricle and sends deoxygenated blood to the lungs. - Pulmonary vein feeds into the left atrium and returns oxygenated blood from the lungs. - Aorta extends from the left ventricle and sends oxygenated blood around the body.
Heart Structure
- a heart is labelled as it would appear in a chest so the left side of an image represents the right side of the heart
Consequences of Coronary occlusion
- can lead to blood clots that cause heart attack or stroke
Ventilation
-The exchange of air between the atmosphere and the lungs - achieved by the physical act of breathing -the purpose of ventilation is to maintain a concentration gradient in the alveoli
Venules
-a large group of capillaries that will later collate into larger veins
Flow of Blood in Capillaries
-high hydrostatic pressure is when shit leaves the capillary -materials like oxygen and nutrients required for cell resp leave -lower hydrostatic pressure is when stuff is reabsorbed by the capillaries - waste products like urea and Co2 are reabsorbed
Atrioventricular node
-if the SA node fails this is the secondary pacemaker -can make the heart beat at roughly 40-60 beats per minute
Fibrillation
-the irregular and uncoordinated contraction of the heart muscle -when this occurs the normal sinus rhythm may be re established with defibrillators
When analysing trends associated with Vaccination Data it is important to remember the following caveats (conditions):
1) Populations have increased year on year, which would be likely to increase the risk of potential outbreaks 2) Improvements to health care services, public sanitation and medical breakthroughs will also influence disease rates 3) Different regions may experience different levels of exposure to particular infections (due to climate and vector presence)
What enzyme would begin the digestion of starch?
1) Salivary Amylase (in the mouth) 2) In the small intestine, the specific organ producing the enzyme is the pancreas = pancreatic amylase.
What protects the lungs and blood vessels?
1) The ribcage protects the lungs and blood vessels. 2) It expands and contracts along with the lungs to allow for efficient breathing.
Generally, there are two main factors that contribute to the length of the gestation period:
1. Animal size / mass - larger animals tend to have longer gestation periods (as they tend to produce larger offspring) 2. The level of development at birth - more developed infants will typically require a longer gestation period
The kidney functions as the blood's filtration and water balancing system - it removes metabolic wastes for excretion (3).
1. Blood enters the kidneys via the renal artery and exits the kidneys via the renal vein. 2. Blood is filtered by specialized structures called nephrons which produce urine. 3. The urine is transported from the kidneys via the ureter, where it is stored in the bladder prior to excretion.
How is the structure of the cells of the epithelium of the villi adapted to the absorption of food?
1. Food has to pass through tight junctions which ensure that materials have to pass through the epithelial cell to gain access to the bloodstream. 2. Microvilli/brush border increases the surface area for absorption. 3. There are also large numbers of mitochondria to generate large amounts of ATP through aerobic respiration from the food.
A typical trace might look as follows:
1. From this you can measure the ventilation rate i.e how many breaths in 1 minute and also the volume of air taken in (or taken out) in a normal, unforced inspiration (or expiration). 2. Note the units are ml/kg and so you would need to know the mass of the individual if you were to calculate total volume inhaled/exhaled.
When blood glucose levels are low (e.g. after exercise):
1. Glucagon is released from alpha (α) cells of the pancreas and cause an increase in blood glucose concentration 2. This may involve stimulating glycogen breakdown in the liver (glycogenolysis), promoting glucose release by the liver and adipose tissue, or decreasing the rate of glucose breakdown (by reducing cell respiration rates)
What is melatonin?
1. Melatonin is a hormone produced by the pineal gland within the brain in response to changes in light 2. Light exposure to the retina is relayed via the suprachiasmatic nucleus (SCN) (in the hypothalamus) and inhibits melatonin secretion 3. Melatonin is therefore secreted in response to periods of darkness, resulting in higher concentrations at night
What can you see here?
1. Microscopically a sarcomere will look like this. 2. You can see two myofibrils here with the mitochondria between them. 3. A "Z" line will be found in the middle of the light coloured sections. 4. The Z line region is itself made up of proteins, different to actin and myosin. 5. Two sarcomeres are visible in this image.....one on top of another.
Negative feedback
1. Negative feedback has a stabilizing effect because a change in levels always causes the opposite change. 2. A rise in levels feeds back to decrease production and reduce the level. 3. A decrease in levels feeds back to increase production and raise the level.
Thorax
1. Space in your chest, bordered by ribcage (moving the ribcage outwards / inwards). 2. In thorax you have your lungs. 3. If space (more specifically = volume) in thorax increases - the air goes into the lungs. 4. If volume in thorax decreases - air goes out of lungs.
What systems in our body are needed to get oxygen to our cells?
1. The Breathing System (inhaling & exhaling air). 2. The Circulatory System
The male and female reproductive gametes (sperm and egg) have specialised structures which reflect their functions:
1. The male gamete (sperm) is small and motile and only contributes the male's haploid nucleus to the zygote 2. The female gamete (egg) is large and non-motile and contributes all the organelles and cytoplasm to the zygote
How is tidal volume measured?
1. This volume can be measured using a machine called a spirometer - (from the Latin verb "spirare" - to breathe and the Greek "metron" - to measure) . 2. There is a part of spirometer which acts for the removal of carbon dioxide using "scavenger" that ensures you are not breathing back in high levels of carbon dioxide (from the previously expelled air) because this would artificially increase your breathing rate.
Explain the process of ultrafiltration, including blood pressure, fenestrated blood capillaries and basement membrane
1. Ultrafiltration occurs when hydrostatic pressure forces blood through a semi-permeable membrane, separating blood cells and large proteins from the remainder of the serum 2. Ultrafiltration occurs between the glomerulus and the Bowman's capsule and requires two things to form the filtrate:
The blood to be filtered enters the Bowman's capsule via an afferent arteriole and leaves the capsule via an efferent arteriole:
1. Within the Bowman's capsule, the blood is filtered at a capillary tuft called the glomerulus 2. The efferent arteriole forms a blood network called the vasa recta that reabsorbs components of the filtrate from the nephron
Define, with examples, the term homeostasis. (4 marks)
1. keeping conditions constant / within narrow limits 2. within the body / internal environment 3. e.g., temperature in humans kept at 37 degrees C / other example 4. e.g., blood sugar / glucose in humans kept within limits / other example
Unique surface molecules are used in several ways:
1. viruses recognize and bind to their host using molecules on the surface of the hosts cells 2. living organisms recognize their own cells and cell types using surface molecules 3. living organisms recognize cells that are not part of the organism and also viruses by surface molecules that are not present in that organism (foreign). These molecules trigger the production of antibodies, so they are antigens.
On the diagram of the motor neurone shown below, which label identifies a dendrite? (1 mark)
A
Which of the following is part of the process of ventilation? a. Changes in the volume of the thoracic cavity b. Cellular respiration c. Exchange of gases across the surface of the alveoli d. Exchange of gases across the surface of capillaries
A
Lumen
A: narrow V: wide C: extremely narrow
Function
A: send blood from the heart V: Send blood to heart C: Material exchange with tissues
Hormone controlling absorption of water from the collecting duct
ADH
Acquired Immuno-Deficiency Syndrome (AIDS)
AIDS stands for
What is necessary for the filaments to slide?
ATP hydrolysis and cross bridge formation are necessary for the filaments to slide
between atria and ventricles
AV valves
Distinguish between absorption and assimilation
Absorption: The movement of a fluid or dissolved substances across a membrane Assimilation: The conversion of nutrients into fluid or solid parts of an organism Absorption is taking it into something, assimilation is making it a part of something.
________ possess a specialised excretory system for osmoregulation and the removal of nitrogenous wastes
All animals
Name of highly soluble nitrogenous waste found in bony fish
Ammonia
metabolic processes that occur in prokaryotic cells but not in eukaryotic cells. Eg. Penicillin inhibits cell wall formation in bacteria. OR Tetracycline affects the functioning of 70s ribosomes.
Antibiotics block
they transport blood at high pressure
Arteries have thick walls and narrow lumens because
How is melatonin removed from the body again?
As the hormone is rapidly removed from the blood by the liver, concentrations rise and fall rapidly after a change in secretion.
Nutrient stored by liver: vitamin A
Associated with good vision.
Nutrient stored by liver: vitamin D
Associated with healthy bone growth.
What antibodies does type A blood have?
B antibodies, because B is not considered to be you and hence a foreign body.
The hormones progesterone and LH were measured in a woman's blood over 40 days. When did her menstrual bleed start? (1 mark)
C
that are only a single cell thick because they exchange materials between blood and tissue
Capillaries have walls
What does FSH appear to do in the ovary?
Causes a follicle to mature
1. Atheromas (fatty deposits) develop in the arteries and significantly reduce the diameter of the lumen (stenosis) 2. The restricted blood flow increases pressure in the artery, leading to damage to the arterial wall (from shear stress) 3. The damaged region is repaired with fibrous tissue which significantly reduces the elasticity of the vessel wall 4. As the smooth lining of the artery is progressively degraded, lesions form called atherosclerotic plaques 5. If the plaque ruptures, blood clotting is triggered, forming a thrombus that restricts blood flow 6. If the thrombus is dislodged it becomes an embolus and can cause a blockage in a smaller arteriole
Causes of Coronary Occlusion
If blood glucose is too low
Cell bursting
Atherosclerosis
Changes in the walls of large arteries consisting of lipid deposits on the artery walls.
What is the role of the collecting duct:
Collecting ducts are the last opportunity to resorb H2O and concentrate urine. It passes right through the medulla and is regulated (turned on and off by the release of hormones, specifically ADH from the endocrine gland in the brain = pituitary gland). Hence, your brain detects the blood becoming too hypertonic = dilute sends a signal to (hypothalamus) pituitary gland.
Which factors could cause emphysema? I. Air pollution II. Genetic predisposition III. Tobacco smoke A. I and II only B. I and III only C. II and III only D. I, II and III
D. I, II and III
What is the main role of nerves in human movement? A. To cause muscles to stretch B. To move joints C. To transport pain signals that indicate muscle injuries D. To stimulate muscle contraction
D. To stimulate muscle contraction
as percent triglycerides increases, density goes down
Data-based Q: 1 (i)
Africa (4.00 YLD/1000)
Data-based Q: 1a
A pathogen is a disease-causing micro-organism, virus or prion
Define pathogen
1. immunoglobulins are antibodies ✓ 2. variety of binding sites / variable regions for binding ✓ 3. specific to antigens on bacteria/viruses/pathogens ✓ 4. constant region aids destruction of the bacteria/virus/pathogen ✓ 5. attracts phagocytes/macrophages to engulf pathogen ✓ 6. bursting pathogen cells/agglutination/neutralizing toxins/other example of the action of antibodies ✓
Describe the functioning of immunoglobulins. [3]
1. antigens are foreign substances/pathogens; 2. antigens stimulate antibody production (an immune response); 3. antibodies are made by B-cells/lymphocytes/plasma cells; organisms causing disease/pathogens have antigens (on their surface); 4. pathogen/antigen is engulfed by macrophages; 5. antigen is presented on macrophage membrane/on an MHC protein; 6. helper T-cell bind to antigen (on macrophage) / recognizes the antigen displayed on the surface of the macrophage. 7. helper T-cell are activated; 8. helper T-cell activate B-cell; 9. helper t cell sends a chemical message to activate B - cell; 10. B-cells clone produced by mitosis; 11. majority enlarge to form plasma cells (with extra rER, Golgi apparatus, mitochondria, other organelles, etc.)and a few remain as memory cells; 12. plasma cells produce specific antibodies to the antigen; 13. memory cells for long-term immunity; 14. a faster/stronger response later;
Describe the production of antibodies: [8 max]
production: 1. antigens injected into animal; 2. B-cells/plasma cells producing antibody (to injected antigen) 3. extracted from animal; 4. B-cells fused with tumor cell/melanoma; 5. hybridoma produced; 6. proliferation of cells/cloning; antibodies produced and purified (in fermenters); use in diagnosis and treatments: 1. one example of detection described (e.g. detection of HCG in pregnancy test); 2. an example of treatment described (e.g. injection of monoclonal antibodies in 3. person infected with rabies, use to deliver toxins to tumour cells);
Describe the production of monoclonal antibodies and their use in diagnosis and treatment. (6)
Glucose in urine in indicative of this illness/condition
Diabetes
1) As blood exits the ventricle and travels down the aorta, ventricular pressure falls 2) When ventricular pressure drops below aortic pressure, the aortic valve closes to prevent back flow (second heart sound) 3) When the ventricular pressure drops below the atrial pressure, the AV valve opens and blood can flow from atria to ventricle 4) Throughout the cycle, aortic pressure remains quite high as muscle and elastic fibres in the artery wall maintain blood pressure
Diastole
*showing the four chambers, associated blood vessels, valves and the route of the blood through the heart*
Draw and label a diagram of the heart:
1. The HIV virus infects helper T cells (infects the very cells that are trying to kill it). 2. The virus replicates many thousands of copies within the helper T cell and these copies then leave the cell. 3. The cell is killed in the process. 4. A reduction in the number of lymphocytes reduced the body's ability to produce antibodies to fight infection. 5. This leads to a collection of symptoms (syndrome). 6. The body eventually succumbs to illness such as pneumonia, meningitis - infection of the brain, tuberculosis, cancers, chronic diarrhea.
Effects of HIV on the immune system:
__________ fuse together to form large multi nucleated muscle fibres. They are much longer than typical cells and can be up to 40cm in length.
Embryonic muscle cells
Explain the need for enzymes in digestion
Enzymes are biological catalysts which speed up the rate of a chemical reaction (e.g. digestion) by lowering the activation energy, allow digestive processes to occur at body temperature and at sufficient speed to meet the organism's survival requirements and are specific for a given substrate and so can allow digestion of certain molecules to occur independently of others
monomers in the small intestine
Enzymes digest most macromolecules in food into ______
The pancreas secretes
Enzymes into the lumen of the small intestine
What is something that you would eat that has nucleic acids?
Everything that has cells & nuclei & DNA in the nucleus.
C
G11 HL Semester 1 Exam Jan 2020 Q:
D
G11 HL Semester 1 Exam Jan 2020 Q:
x 15,000 (accept answers in the range of x 14,000 to x 16,000)
G11 HL Semester 1 Exam Jan 2020 Q:
Gametogenesis
Gametogenesis is the process by which diploid precursor cells undergo meiotic division to become haploid gametes (sex cells)
Human Immunodeficiency Virus
HIV stands for
What does this image show?
Here are some images of primary and secondary follicles containing primary and secondary oocytes respectively.
What does this drawing show?
Here is a drawing of a cross section of the proximal convoluted tubule. Again note the adaptations.
"Explain how the structure of nephron and its associated blood vessels enable the kidney to carry out its function"
Here is a summarized version of the markscheme: 1. Osmoregulation/Excretion of urea happens in the kidney; 2. Ultrafiltration in the glomerulus; 3. Basement membrane acts a filter; 4. High (blood pressure) in the glomerulus due to larger afferent diameter than efferent arteriole diameter; 5. (Selective) reabsorption of glucose in the proximal convoluted tubule; 6. Microvilli (in cells lining the proximal convoluted tubule) increase the surface area; 7. Water reabsorbed in descending limb of loop of Henle; 8. Active transport of sodium ions takes place in the ascending limb (of loop of Henle); 9. Ascending limb is impermeable to water; 10. Loop of Henle creates a high solute concentration in the medulla; 11. Distal convoluted tubule adjusts concentrations of ions/sodium/potassium/hydrogen; 12. Water is reabsorbed in the collecting duct; 13. Collecting duct permeability varies due to ADH; 14. Osmoregulation happens by varying the volume of water reabsorbed in the collecting ducts;
What does this image show?
Here is an image of the womb lining - the blastocyst imbeds/implants itself into this lining, which is called the endometrium.
What does this Data Table show?
Here is data showing the Relative Medulla Thickness (RMT) and the Maximum Solute Concentration (MSC) of the filtrate that is achievable in the Loop of Henle. The greater the RMT the more concentrated is the filtrate/urine.
What is this?
Here is what a dissected kidney would look like. The renal pyramids are found in the medulla region of the kidney. Note the misspelling of the ureter.
Maintaining an appropriate water balance within the body's tissues and cells is critical to the survival of an organism:
Homeostasis cannot be maintained if water levels drop (dehydration) or are raised (overhydration) without regulation
How many pairs of chromosomes do human cells have?
Humans have 23 pairs of chromosomes--22 pairs of body (numbered) chromosomes, called autosomes, and one pair of sex chromosomes, X and Y.
What effect does this slow increase in oestrogen secretion have on FSH and LH?
In the follicular phase, it has a positive feedback effect on FSH and LH
Here is drawing of a spirometer:
In this drawing you will note that pure oxygen has been put in the chamber/under the lid. This allows you to take readings for longer when compared to when the chamber is filled with normal air. You are NOT expected to know the functioning of the following piece of apparatus but you are expected to be able to interpret the results that come from it.
Outline the process of in vitro fertilisation
In vitro fertilisation refers to fertilisation that occurs outside the body ('in vitro' = 'in glass') Stop normal menstrual cycle (with drugs) Hormone treatments to develop follicles (FSH to stimulate follicle growth ; hCG for follicle maturation) Extract multiple eggs from ovaries Sperm selected, prepared (capacitation) and then injected into egg via intra-cytoplasmic sperm injection (ICSI) Fertilisation occurs under controlled conditions (in vitro) Implantation of multiple embryos into uterus Test for pregnancy is conducted to see if implantation was successful
What becomes of the Graafian follicle after ovulation? Which hormone causes this?
It becomes the corpus luteum under the influence of the LH and FSH
Be able to identify the regions in the picture below.
It caused some confusion when asked to identify the cortex and the pelvis in a recent exam. The word "cortex" in Latin indicates the bark of a tree, hence it is on the outside. "Medulla" in Latin means the "pith or the marrow, like bone marrow" indicating it is in the middle."Pelvis" is the Latin for "a basin" thus indicating the hollow like basin in the kidney collecting urine and directing it to the ureter. The french verb "uretere" means to urinate hence the term "ureter".
1) The contraction of the heart tissue (myocardium) is myogenic, meaning the signal for cardial contraction arises within the heart muscle itself 2) Within the wall of the right atrium are a specialised plexus of nerves called the sinoatrial node (SAN) 3) The sinoatrial node initiates contraction of the cardiac muscle and acts as a pacemaker, regulating normal sinus rhythm 4) It stimulates atria to contract and, when excitation reaches the junction between atria and ventricles, stimulates another node (atrioventicular node) 5) The atrioventricular node (AVN) sends signals via the Bundle of His to Purkinje fibres, which cause ventricular contraction 6) This sequence always ensures their is a delay between atrial and ventricular contractions, resulting in two heart sounds ('lub dub')
Myogenic Control of the Heart Beat
Is air just oxygen (the air that you exhale)?
No, the air you breath out also contains a variety of gases, it contains oxygen (16% = less than inhaled, because it's used), nitrogen (78% = same, because we do not take it from the air = we take it from food that we eat, because plants take in the nitrogen convert it into nucleotides and amino acids and then we can access it, but in reality plants live with bacteria in their roots = a symbiotic relationship, where the bacteria takes up the nitrogen in the soil and gives the plants everything it needs = Digestive System), CO2 (4% = more = 100% more than air you breath in, because it went from 0.004% to 4%) water vapour (H2O gas = the % depends on the conditions, whether it is a very dry day or humid),
Annotate a diagram of the stages in spermatogenesis:
Note that "germin" is the Latin word for a "seed" and "epithelium" means outer layer of cells.
You need to be able to annotate a diagram of a seminiferous tubule to show the stages of spermatogenesis.
Note that "germin" is the Latin word for a "seed" and "epithelium" means outer layer of cells.
Can you deduce the blood types in the results below? Agglutination means that the red blood cells have been clumped together due to the presence of antibodies that bind to the antigen that is present on the red blood cell plasma membrane. Agglutination when anti A is added means that you have the antigen to this antibody present on the surface of your red blood cells.
Note that the antigens that are mentioned above are proteins found on the plasma membrane of red blood cells (also caller erythrocytes). They were made on the rER and modified in the Golgi apparatus. Vesicles transported them from rER to Golgi and eventually to the membrane. The different antigens have different types of sugars attached to the protein. When we say that a Golgi modifies/changes protein we mean it add molecules to them e.g sugar units. The reason that antibodies are already present in your body to these antigens is that they are commonly found in nature e.g in your food and so the reason for an immediate reaction. Antibodies are already circulating in your bloodstream.
1. "Opson" in ancient Greece referred to the delicious side-dish that might accompany a meal. 2. Opsonisation is a molecular mechanism whereby microbes are chemically modified to be made more "Delicious" for phagocytes!! 3. The antibody triggers a series of reactions involving many plasma proteins which forms a collection of proteins on the pathogen surface. The pathogen has now undergone "opsonisation". and is more readily engulfed by the phagocyte, because it is more delicious / attractive for him.
Opsonisation
______ are scientific instruments that are used to measure the membrane potential across a neuronal membrane
Oscilloscopes
Osmoregulation is the third of three processes by which blood is filtered and urine is formed:
Osmoregulation is the control of the water balance of the blood, tissue or cytoplasm of a living organism
William Harvey
Our modern understanding of circulatory system is based upon the discoveries of 17th century English physician:
From days 0-12 oestrogen secretion increases. i) From where is oestrogen secreted?
Ovarian follicles and corpus lute
Data Based Q's: Polio incidence in 2012 This figure provides data about polio incidence in the three countries where wild polio was endemic as of mid-2012. Identify one country where the situation appears to have improved between 2011 and 2012 (2)
Pakistan is the only country where year to date comparison shows a total decline.
Why are people different blood groups?
People are different (have different) blood groups, because of the different antigens on their red blood cells.
pathogens by endocytosis and digest them with hydrolytic enzymes from lysosomes (lysosomes form from the Golgi apparatus).
Phagocytes engulf
Name of cells which line the Bowman's capsule
Podocytes
Some pathogens are species-specific and only infect members of a single species. Examples:
Polio, measles and syphilis only affect humans.
Positive feedback
Positive feedback tends to lead to sudden rises or falls, because a rise causes further rises and a fall causes further falls.
specific immunity
Production of antibodies by lymphocytes in response to particular pathogens gives
What do prolonged deficiencies of iodine cause?
Prolonged deficiency of iodine in the diet therefore prevents the synthesis of thyroxin.
Explain the difference in the concentration of proteins, glucose and urea between blood plasma, glomerular filtrate and urine
Proteins: 1. Proteins will be present in blood plasma, but not present in glomerular filtrate or urine 2. This is because proteins cannot pass across the basement membrane during ultrafiltration and thus cannot form part of the filtrate Glucose: 1. Glucose will be present in blood plasma and glomerular filtrate, but not present in urine (normally) 2. This is because the glucose is selectively reabsorbed in the proximal convoluted tubule 3. It is reabsorbed from the filtrate into the blood by active transport (symport with Na+ ions) Urea: 1. Urea will be present in blood plasma, glomerular filtrate and urine 2. Only about 50% of urea is reabsorbed (some urea is reabsorbed to help regulate the medullary osmolarity gradient) 3. Because water is reabsorbed from the filtrate (by osmosis, due to the hypertonicity of the medulla), urea becomes more concentrated in urine 4. The concentration of urea in the urine will depend on the amount of water in the urine
Medical term for the kidney
Renal
Blood vessel carrying blood away from the kidney (2 Words)
Renal Vein
What ions are causing repolarisation?
Repolarization is caused by the closing of sodium ion channels and the opening of potassium ion channels.
When a nerve cell is not conducting an impulse it is said to be in a state called a
Resting Potential.
Risks of external fertilisation
Risks of external fertilisation include predation, susceptibility to environmental change e.g. pH, temp, pollution
a = aorta b = pulmonary arteries c = left atrium d = pulmonary veins e = atrio-ventricular (AV) valve f = left ventricle g = right ventricle h = atrio-ventricular (AV) valve i = vena cava (inferior) j = semilunar valves k = right atrium l = vena cava (superior)
STRUCTURE OF THE HEART
Before the beginning of the Loop of Henle ...
Some of the water, some minerals and all glucose and amino acids should be gone / reabsorbed.
multiple resistance
Some strains of bacteria have evolved with genes that confer resistance to antibiotics and some strains of bacteria have
Comparison of Spermatogenesis and Oogenesis: Where are both located?
Spermatogenesis in the testes. Oogenesis in the ovaries.
Comparison of Spermatogenesis and Oogenesis: Which involves testosterone?
Spermatogenesis involves testosterone. Oogenesis not.
Comparison of Spermatogenesis and Oogenesis: Production
Spermatogenesis millions every day. Oogenesis 1 per month (once every 28 days).
1. The heart is a muscle that must continually contract in order to pump blood around the body 2. Coronary arteries form a network of vessels around the heart and supply the cardiac tissue with oxygen and nutrients (i.e. glucose) 3. These are required to produce the necessary energy via aerobic respiration - if a coronary artery is blocked, a heart attack may occur
State what coronary arteries supply what with?
1. Antibodies are made up of 4 polypeptide chains (2 light and 2 heavy chains) joined together by disulphide bonds to form a Y-shaped molecule 2. The ends of the arms are where the antigens bind and these areas are called the variable regions, as these will differ between antibodies 3. Each type of antibody will recognise a unique antigenic fragment, making this interaction specific (like enzyme-substrate interactions)
Structure of a Generalised Antibody
1. They have a narrow lumen (relative to wall thickness) to maintain a high blood pressure (~ 80 - 120 mmHg) 2. They have a thick wall containing an outer layer of collagen to prevent the artery from rupturing under the high pressure 3. The arterial wall also contains an inner layer of muscle and elastic fibres to help maintain pulse flow (it can contract and stretch)
Structure of a Typical Artery
1) Heart cells can contract on their own/myogenic 2) Muscle contractions/heartbeat starts at the SAN/pacemaker/sinoatrial node (located in the wall of the right atrium). 3) Signal is transmitted across the wall of the atria (via the AV node), which initiates atrial muscle contraction/atrial sytole. 4) SAN node can be influenced by chemicals e.g adrenaline which increases rate of contraction. 5) SAN node can be influenced by nerves from the medulla region of the brain 6) There are both accelerator and decelerator nerves from the brain that lead to the SAN 7) Vagus nerve slows down the pacemaker/is the decelerator nerve 8) Electrical impulse/action potential reaches the AVN 9) Delay at the AVN ensures atrial contraction before ventricular contraction. 10) Impulses down the septum to the apex of the heart 11) Impulse moves upward through the ventricles in the Purkinje fibres, which causes ventricular systole
Summary of the passage of electrical conductivity through the heart muscle/cardiac muscle:
Evaporates to cool you down
Sweat
B lymphocytes are activated by
T lymphocytes in mammals
Steroid Hormones in the Reproductive Systems:
Testosterone, estrogen and progesterone are all steroids.
A) Atrium contracts: 1. Blood flows into the ventricles 2. On the ECG, this is recognised by the P wave (atrial systole), which fills the ventricles with blood.
The Cardiac Cycle: What happens at A?
D) Ventricular pressure falls below aortic pressure: 1. this forces the closure of the aortic valve 2. this is the "dub"=2nd heartbeat of the phonocariogram 3. ventricular volume starts to rise again
The Cardiac Cycle: What happens at D?
E) Ventricular pressure falls below atrial pressure: 1. this allows the opening of the AV valves 2. blood begins to drain into the ventricles again and ventricular volume rises quickly.
The Cardiac Cycle: What happens at E?
F) Atrial pressure exceeds ventricular pressure: 1. This occurs as the atrium fills with blood from the pulmonary vein 2. ventricle becomes 70% full simply by the "draining of blood" from the atrium.
The Cardiac Cycle: What happens at F?
1. The discovery of penicillin was a fortuitous accident, resulting from the unintended contamination of a dish containing S. aureus 2. A Penicillium mould began to grow on the plate and a halo of inhibited bacterial growth was observed around the mould 3. Fleming concluded that the mould was releasing a substance (penicillin) that was killing the nearby bacteria
The Discovery of Penicillin by Fleming
In males
The Gametogenesis process is called spermatogenesis and produce spermatozoa (sperm) In females, this process is called oogenesis and produce ova (eggs)
infects helper T cells, disabling the body's adaptive immune system, which causes a variety of symptoms and infections collectively classed as Acquired Immuno-Deficiency Syndrome (AIDS)
The Human Immunodeficiency Virus (HIV) is a retrovirus that
60 - 100 cardiac contractions per minute (normal sinus rhythm) BPM
The SA node triggers roughly:
nerves from the medulla to the SAN.
The SAN can be influenced by the nervous system via
left ventricle
The aorta leaves the heart from the
It also brings oxygen for aerobic cell respiration, which provides energy for cardiac muscle contraction.
The blood brought by the coronary arteries brings nutrients:
Why has the blood got low oxygen?
The blood gave the oxygen to the cells of the body, where it can use it for aerobic respiration.
What are the capillaries of the glomerulus surrounded by?
The capillaries of the glomerulus are surrounded by podocytes. These cells form the inner lining of the Bowman's capsule - the first region of the nephron.
Each nephron connects to a collecting duct (via the distal convoluted tubule), which feed into the renal pelvis:
The collecting ducts are shared by nephrons and hence are not technically considered to be part of a single nephron
the food with enzymes and moves it along the gut
The contraction of circular and longitudinal muscle of the small intestine mixes _____
From days 14-23 progesterone secretion increases. i) From where is progesterone secreted?
The corpus luteum
ii) Why do progesterone and oestrogen levels decline at the end of the cycle?
The corpus luteum atrophies
Starch Digestion
The digestion of starch is initiated by salivary amylase in the mouth and continued by pancreatic amylase in the intestines.
digestive system
The digestive system (7 meters of it!!) converts large polymers into smaller monomers that can be absorbed into the blood stream and transported to cells where the monomers are needed for anabolic (build proteins / triglycerides / phospholipids / DNA, etc.) and catabolic (e.g. respiration) reactions in cells.
there are separate circulations for the lungs (pulmonary circulation) and for other organs of the body (systemic circulation).
The double circulation: The circulation that Harvey discovered in humans is double:
For mammals, the gestation period is the time taken for a foetus to develop - beginning with fertilization and ending with birth:
The duration of the gestation period will differ markedly between different species of animal
the intact skin and mucous membranes
The first line of defence against infectious disease are the surface barriers that prevent the entry of pathogens into the body. These surface barriers include both
1. Nutrients (e.g. glucose) 2. Antibodies 3. Carbon dioxide 4. Hormones 5. Oxygen 6. Urea 7. Heat (not a molecules, unlike all the others)
The following things are transported by blood:
What does this graph show?
The graph below also shows the "undershoot" region or the region of hyperpolarisation which stops the impulse going "backwards". Note also the region resulting from the localised currents before the threshold level is reached and rapid depolarisation occurs.
1. The right side pumps deoxygenated blood to the lungs via the pulmonary artery. 2. Oxygenated blood returns to the left side of the heart in the pulmonary vein. 3. The left side pumps this blood via the aorta to all organs of the body apart from the lungs. 4. Deoxygenated blood is carried back the right side of the heart in the vena cava.
The heart is a double pump with left and right sides:
impulses brought to the heart through two nerves from the medulla of the brain
The heart rate can be increased or decreased by
a group of specialised muscle cells in the wall of the right atrium called the pacemaker or the sinoatrial node.
The heartbeat is controlled by
reserviors, by which blood returning to the heart is collected via veins (and passed on to ventricles)
The human heart is a four chambered organ, consisting of two atria and two ventricles. The atria act as
pumps, expelling the blood from the heart at high pressure via arteries
The human heart is a four chambered organ, consisting of two atria and two ventricles. The ventricles act as
Diagram of the Propagation of a Nerve Impulse:
The image below has the action potential being propagated from left to right.
Outline the function of the large intestine
The large intestine absorbs water and dissolved minerals from the indigestible food residues, and by doing so converts what remains from a fluid state into a semi-solid faeces.
thicker muscular wall (myocardium) as it must pump blood much further
The left side of the heart will have a much
Liver and red blood cells (5)
The liver recycles old erythrocytes. 1. Red blood cells burst after about 4 months, releasing millions of hemoglobin molecules. 2. Kupffer cells ingest the hemoglobin molecules into sinusoids. 3. The 4 polypeptides are broken down into amino acids; iron atom is removed from heme group. 4. Some iron is stored in the liver; some sent to bone marrow to make new erythrocytes. 5. Remainder of heme group called bilirubin or bile pigment.
What are the white things and their extensions in this image?
The many mucus producing cells (the white ones) are responsible for the mucosa layer. The extensions visible in the image represent villi. A lacteal is visible in the large centrally located villus.
What does this image show?
The maturing follicle contains a secondary oocyte with its nucleus stopped in meiosis II.
Ventilation
The movement of air into and out of the lungs. - Lungs are made of passive tissues. - Muscles attached to thorax cause inhalation and exhalation. - Has to do with inverse relationship between volume and pressure; if the muscles expand the thorax, volume goes UP, pressure goes DOWN, and air comes IN (and vice versa).
When muscle fibres contract, actin filaments slide along the myosin, reducing the length of the lighter I bands:
The movement of the actin filaments also reduces the width of the H zone, however the length of A bands do not change
Nerve signaling (2)
The pacemaker is under autonomic (involuntary) control from the brain, specifically the medulla oblongata (brain stem). Two nerves connected to the medulla regulate heart rate by either speeding it up or slowing it down: 1. The sympathetic nerve releases the neurotransmitter noradrenaline (a.k.a. norepinephrine) to increase heart rate. 2. The parasympathetic nerve (vagus nerve) releases the neurotransmitter acetylcholine to decrease heart rate.
Role of Pancreas
The pancreas serves two functions in the breakdown of starch: 1) It produces the enzyme amylase which is released from exocrine glands (acinar cells) into the intestinal tract 2) It produces the hormones insulin and glucagon which are released from endocrine glands (islets of Langerhans) into the blood
From days 10-14 LH (luteinising hormone) secretion increases with a sudden surge. i) From where is LH secreted and what caused this surge?
The pituitary, and the level of oestrogen reaching a trigger point.
1. Antibiotics are often over-prescribed (particularly broad-spectrum drugs) or misused (e.g. given to treat a viral infection) 2. Many antibiotics are freely available without a prescription and certain antibiotics are commonly included in livestock feed 3. Multi-drug resistant bacteria are especially common in hospitals (i.e. nosocomial infections) where antibiotic use is high
The prevalance of resistant bacterial strains is increasing rapidly with human populations due to a number of factors:
What does the Proximal Convoluted Tubule (PCT) reabsorb?
The proximal tubules reabsorb about 65% of water (not all of it = some), some minerals (eg. sodium, potassium and chloride), 100% (all) of glucose and (all) 100% amino acids. = SELECTIVE REABSORPTION happens in the PCT. DO NOT REABSORB UREA!!!
deoxygenated blood to the lungs (pulmonary circulation)
The right side of the heart pumps
electrical signal that stimulates contraction as it is propagated through the walls of the atria and then the walls of the ventricles
The sinoatrial node sends out an
primary defence against pathogens that cause infectious disease
The skin and mucous membranes form a
Outline the function of the small intestine
The small intestine is where unsuable food substances (e.g. nutrients = amino acids, glucose, fructose) are absorbed into the bloodstream.
a. hypoxia increases the concentration of sodium-potassium pumps (with and without inhibitor) b. nitric oxide needed stimulates (production of) sodium-potassium pumps (in both control and hypoxic group) c. nitric oxide synthase inhibitor reduces the concentration of pumps OR concentration of pumps reduced by inhibiting nitric oxide production (in both control and hypoxic group)
The sodium-potassium pump plays a role in muscle activity. Nitric oxide may have a role in the recovery of hypoxic muscles. The production of nitric oxide can be blocked with an inhibitor of the enzyme nitric oxide synthase. The graph shows the concentration of sodium-potassium pumps in the diaphragm of control and hypoxic rats without and with nitric oxide synthase inhibitor. Analyse the graph to obtain two conclusions about the concentration of sodium-potassium pumps. [2 marks]
Stomach Acids
The stomach contains gastric glands which release digestive acids to create a low pH environment (pH ~2), which denature proteins and other macromolecules, aiding in their overall digestion
How are the acids prevent from damaging the gastric glands of the stomach?
The stomach epithelium contains a mucous membrane which prevents the acids from damaging the gastric lining.
Chambers 1. Two atria (singular = atrium) - smaller chambers near top of heart that collect blood from body and lungs 2. Two ventricles - larger chambers near bottom of heart that pump blood to body and lungs Heart Valves 1. Atrioventricular valves (between atria and ventricles) - bicuspid valve on left side ; tricuspid valve on right side 2. Semilunar valves (between ventricles and arteries) - aortic valve on left side ; pulmonary valve on right side Blood Vessels 1. Vena cava (inferior and superior) feeds into the right atrium and returns deoxygenated blood from the body 2. Pulmonary artery connects to the right ventricle and sends deoxygenated blood to the lungs 3. Pulmonary vein feeds into the left atrium and returns oxygenated blood from the lungs 4. Aorta extends from the left ventricle and sends oxygenated blood around the body
The structure of the human heart includes the following key components:
You need to be able to annotate a diagram of the ovary to describe the stages of oogenesis.
The term "germinal" is from the Latin "germen" - a seed. The term "epithelium" comes form the Greek meaning "epi" - upon/on and 'thele" meaning nipple. A strange word that was first used to describe the outer covering of the small nipples/folds you find on your lips!!
Here is a typical graph derived from a spirometer. Typical questions would include: 6. Why is the trace tending to move down the papers as time goes on?
The trace is tending to move down the papers as time goes on, because the oxygen in the chamber is decreasing over time.....it is being used in aerobic respiration.
The proximal convoluted tubule has a microvilli cell lining to increase the surface area for material absorption from the filtrate:
The tubule is a single cell thick and connected by tight junctions, which function to create a thin tubular surface with no gaps
Macroscopic structure of the kidney
The urinary system is not specifically on the course but it may help you to get an overall idea of where the kidneys fit in regarding the production and release of urine.
it can contract on its own without being stimulated by a nerve (myogenic contraction).
The walls of the heart are made of cardiac muscle, which has a special property:
What is the function of neurons?
Their function is to transmit nervous impulses. The term "dendron" comes from the Greek for "a tree" and "dendrite" means "tree like"
1. Plasma - the fluid medium of the blood 2. Erythrocytes - red blood cells (involved in oxygen transport) 3. Leukocytes - white blood cells, such as phagocytes (non-specific immunity) and lymphocytes (specific immunity) 4. Platelets - responsible for blood clotting (haemostasis)
There are four main components to blood:
the coronary arteries, which branch of the aorta, close to the semilunar valve.
There are many capillaries in the muscular wall of the heart. The blood running through these capillaries is supplied by
(left side of heart)
There is therefore a separate circulation for the lungs (right side of heart) and for the rest of the body
cell 2 because it has plasmolized/lost water = volume has decreased
These images show two red blood cells that have been placed in solutions with different concentrations of solutes. Deduce, with a reason, which red blood cell has been placed in a hypertonic solution. [1 mark]
cell surface area to volume ratio in red blood cell 1 decreased
These images show two red blood cells that have been placed in solutions with different concentrations of solutes. State what change there has been in the cell surface area to volume ratio in red blood cell 1.
Describe the features of alveoli that adapt them to gas exchange
Thin wall: Made of a single layer of flattened pneumocytes so that diffusion distance is small Rich capillary network: Alveoli are covered by a dense network of capillaries that help to maintain a concentration gradient Increased SA:Vol ratio: High numbers of spherically-shaped alveoli optimise surface area for gas exchange (600 million alveoli = 80 m2) Moist: Type II Pneumocytes in the lining secrete fluid to allow gases to dissolve and to prevent alveoli from collapsing (through cohesion)
1. The muscle fibres help to form a rigid arterial wall that is capable of withstanding the high blood pressure without rupturing 2. Muscle fibres can also contract to narrow the lumen, which increases the pressure between pumps and helps to maintain blood pressure throughout the cardiac cycle 3. The elastic fibres allow the arterial wall to stretch and expand upon the flow of a pulse through the lumen 4. The pressure exerted on the arterial wall is returned to the blood when the artery returns to its normal size (elastic recoil) 5. The elastic recoil helps to push the blood forward through the artery as well as maintain arterial pressure between pump cycles
This blood flows at a high pressure and the muscle and elastic fibres assist in maintaining this pressure between pumps:
What does this graph show?
This graph outlines changes in peak melatonin concentrations in people of different ages. It may help to explain why older people tend to sleep less than younger people.
What does this image show?
This image shows two follicles each containing an egg/ovum inside. The egg will be released at ovulation and the follicle will become the corpus luteum/yellow body. This will produce progesterone to maintain the womb lining. Note that the blue circular structure inside the fluid filled cavity is the ovum. The fluid filled cavity is part of the follicle. The Corpus Luteum is the remains of the follicle after ovulation and is responsible for increased progesterone (and estrogen) production.
The respiratory system allows us to take in oxygen and remove carbon dioxide. Why is this essential?
This is essential, as all cells need oxygen in order to function. As a byproduct of cellular processes, cells produce carbon dioxide, which must be removed or else it becomes toxic within the body.
Here is a typical graph derived from a spirometer. Typical questions would include: 2. Calculate the tidal volume of the first breath.
This is the volume of air taken in (OR exhaled) during a breath at rest. They might ask you to calculate a mean value for say breaths 1,2 and 3..............add tidal volumes from breath 1,2 and 3 and divide by 3.
What is the name of the space where you find your lungs and your heart?
Thorax (the ribcage makes up the cage, the chestbone is at front, backbone in the back, diaphragm is at the bottom, open at the top = inhale & exhale).
Hormone that increases metabolic rate in order to increase body temperature
Thyroxine
eliminate the pathogen and leave both memory T and B cells behind to allow for immunity.
Together the T cells & B cells will
Cartillage
Tough but flexible tissue that acts as a buffer between the bones at joints (eg. the rings along the trachea, in your ears, etc.)
What is a hormone that is used in response to anaphylactic shocks?
Treatment is with adrenaline (aka. epinephrine) = in epipens to inject high amounts of adrenaline - greater than what the body can naturally produce.
Chambers
Two atria, the two smaller chambers near the top of the hear that collect blood from body and lungs two ventricles-large chambers near bottom of heart that pump blood to the body and lungs
1) The sympathetic nerve releases the neurotransmitter noradrenaline (a.k.a. norepinephrine) to increase heart rate 2) The parasympathetic nerve (vagus nerve) releases the neurotransmitter acetylcholine to decrease heart rate
Two nerves connected to the medulla regulate heart rate by either speeding it up or slowing it down:
Type I & Type II pneumocytes
Type I: Very thin with large membrane surface area. Well designed for diffusion, but cannot replace themselves. Type II: Cuboidal in shape with relatively little surface area. Secrete a SURFACTANT that reduces surface tension and prevents alveoli (alveoli walls) from sticking to each other and can not inflate / exflate. (premature babies do not have surfactant and can not breath on their own = need to be injected with it). Capable of mitosis for replacement of both types.
What do type II pneumocytes do?
Type II pneumocytes secrete a solution containing surfactant that creates a moist surface inside the alveoli to prevent the sides of the alveolus adhering to each other by reducing surface tension
Type II pneumocytes
Type II pneumocytes secrete a solution which has a number of functions: 1. coats the inner lining of the alveolus allowing oxygen in the alveolus to dissolve and then diffuse in solution to the blood in the alveolar capillaries 2. coats the inner lining of the alveolus allowing carbon dioxide to evaporate into the air in the alveolus and be exhaled 3. contains a surfactant solution, similar to phospholipids that form a monolayer of the surface of the moisture lining the alveolus. The hydrophobic tails face the air. This prevents the sides of the alveoli from adhering to each other when air is exhaled as it prevents cohesive water molecules making contact with each other. (Note premature babies receive injections of pulmonary surfactant derived from the lungs of other mammals!!)
Here is a typical graph derived from a spirometer. Typical questions would include: 5. They may ask you to suggest a procedure to measure a persons tidal volume.
Use a spirometer, measure volume of air inhaled/exhaled during breathing at rest, calculate an average.
Lysosome
Used to bury through the ovary membrane to get to the egg (secondary oozyte).
a. effective because erythrocyte percentage increases b. effective because body mass still increases/rats still grow c. effective because mass of right ventricle increases d. effective because more sodium-potassium pumps so more/faster rate of diaphragm/muscle contractions e. effective because endurance of diaphragm increases f. not effective because contractions/force exerted by diaphragm decreases g. not effective because body mass lost *For each marking point the candidate must make it clear whether they are arguing for adaptation being effective or not. This can be done by giving the physiological benefit of a change, for example greater mass of right ventricle so more blood pumped.*
Using all relevant data in the question, evaluate the effectiveness of the rats' adaptation to hypoxia. In this question you need to say whether it is effective/not effective/you cannot say one way or the other and then say why. You can have answers that relate to more than one possibility. [3 marks]
absorption is carried out
Villi increase the surface area of epithelium over which _____
metabolism of the host cell and so anything that would target vital reactions required by the virus would also kill the host cell. As a result vaccines are a solution to the control of viral infection.
Virus relies on the
metabolism of their own and so cannot be treated with antibiotics.
Viruses lack a
cannot be treated with antibiotics
Viruses lack a metabolism and therefore
Data Based Q's: Polio incidence in 2012 This figure provides data about polio incidence in the three countries where wild polio was endemic as of mid-2012. Identify the strain of polio virus which is the most prevalent (1)
WPV1
T-lymphocytes; they are directly involved with tunor and virus infected cells.
What are T cells?
Two of the valves, the mitral and the tricuspid valves, move blood from the upper chambers of the heart (the atria) to the lower chambers of the heart (the ventricles). The other two valves, the aortic and pulmonary valves, move blood to the lungs and the rest of the body through the ventricles.
What are the different valves of the heart?
atrial systole => AV valve closes (1st heartbeat) => 100% full ventricle => ventricle contracts.
What happens at A?
Aorta
What is the biggest artery that leaves the heart?
re-established with a controlled electrical current (defibrillation)
When fibrillation occurs, normal sinus rhythm may be
White blood cells or more specifically lymphocytes.
Which cells produce antibodies?
Alexander Fleming and Florey & Chain (looking further into the discovery of Penicillin).
Who discovered antibiotics?
1. Blood pumped through the heart is at high pressure and cannot be used to supply the heart muscle with oxygen and nutrients 2. Coronary arteries are the blood vessels that surround the heart and nourish the cardiac tissue to keep the heart working 3. If coronary arteries become occluded, the region of heart tissue nourished by the blocked artery will die and cease to function
Why are coronary arteries important for the heart?
Who is William Bowman?
William Bowman was an English surgeon (1816 - 1892) who gave his name to a structure found in a nephron.
He is well known for his discoveries on the one way flow of blood around the body (from arteries to capillaries to veins):
William Harvey
Annotation of diagrams of mature human egg
You do not have to be able to draw - just annotate structure with function.
Annotation of diagrams of mature human sperm
You do not have to be able to draw - just annotate structure with function.
axon
a elongated fiber that transmit electrical signals to terminal regions for communication with other neurons or effectors
Diabetes mellitus is
a metabolic disorder that results from a high blood glucose concentration over a prolonged period.
Sarcomeres can contract to make
a myofibril and hence a muscle fibre shorter. A sarcomere is the functional unit of a myofibril.
Leptin is
a protein hormone secreted by adipose cells (fat storage cells). If the amount of adipose tissue in the body increases, the concentration of leptin in the blood rises.
hypertonic solution
a solution that causes a cell to shrink because of osmosis = Solute concentration is greater than that inside the cell; cell loses water.
Annotate this microscopic view of the intestinal wall:
a) submucosa b) lumen c) Mucosa d) Blood Vessels e) Circular Smooth Muscle layer f) Longitudinal Smooth Muscle layer
Describe the roles of structures at the elbow joint, including nerves, muscles and bones, inmovements of the human forearm. [8]
abelled diagram showing, biceps, humerus, radius and ulna;cartilage reduces friction;synovial fluid lubricates the joint;synovial membrane secretes synovial fluid;capsule / capsular ligament seals the joint;ligaments prevent dislocation / restrict the range of movement/attach bones to oneanother;motor neurones stimulate muscles to contract;bones provide a firm anchorage for muscles;bones act as levers/change the torque / size / direction of forces;tendons attach muscle to bone;biceps and triceps are antagonistic;biceps is the flexor / bends the elbow joint and triceps is the extensor / straightens theelbow joint;biceps is attached to the radius and triceps is attached to the ulna; [8 max]Accept any of the above points if clearly drawn and correctly labelled in a diagram.
A strain of mice was discovered in the 1950s that feed ravenously, become inactive and gain mass, mainly through increased _________. They grow to a body mass of about 100 grams, compared with wild type mice o2025 grams.
adipose tissue
Leptin concentration is controlled by the amount of
adipose tissue/fat cells.
The nasal cavity or nose allows
air to flow in. Inside the nose, the air is filtered using fine hairs called cilia, removing any harmful particles. There is also sticky mucus produced by goblet cells, which trap particles.
building blocks for proteins which must travel from mother to fetus (2 words)
amino acids
Most aquatic animals eliminate their nitrogenous wastes as
ammonia (NH3): Ammonia is highly toxic but also very water soluble and hence can be effectively flushed by animals in aquatic habitats
Amylase digests
amylose into maltose subunits (disaccharide) and digests amylopectin into branched chains called dextrins.
Circadian rhythms are driven by
an internal (endogenous) circadian clock, although they can be modulated by external factors
Sometimes people produce
an overproduction (too much) histamine in response to harmless antigen (from eg. pollen, dust, peanuts, bee stings) aka. allergy.
Muscles are typically elongated structures, with tendons forming attachments at both ends. One end of the muscle is the ________, which is a firm point of attachment that does not move when the muscle contracts. Bones are used as ____________ in humans and other vertebrates. In insects and other arthropods the exoskeleton provides the __________.
anchorage
Bones and exoskeletons provide for
anchorage of muscle and act as levers
antibiotics are effective against bacteria but not against viruses
antibiotics are effective against ____ but not against _____
Plasma cells secrete
antibodies
defensive proteins produced by the mothers B cells which cross the placenta from mother to fetus
antibodies
proteins - proteins are synthesized by ribosomes / by the rough endoplasmic reticulum
antibodies are
antigen.
antibodies are specific to the pathogen's
variable region.
antibodies prevemt the entry of virus into the cell, because they stick to its______
Antigens on the surface of red blood cells stimulate
antibody production in a person with a different blood group
Any substance that is recognised as foreign and is capable of triggering an immune response is called an
antigen (non self)
Need a protein facilitate diffusion (osmosis = water follows) =
aquaporins (hydrophilic channel through hydrophobic interior)
Explain the relationship between the structure and functions of arteries, capillaries and veins. [9]
arteries carry blood away from the heart / to tissues;arteries have thick walls to withstand high pressure / prevent bursting;arteries have muscle fibres to generate the pulse / help pump blood / even out blood flow;arteries have elastic fibres to help generate pulse / allow artery wall to stretch/recoil;capillaries allow exchange of O2 / CO2 / nutrients / waste products from tissues/cells;capillaries have a thin wall to allow (rapid) diffusion / movement in / out;capillaries have pores / porous walls to allow phagocytes / tissue fluid to leave;capillaries are narrow so can penetrate all parts of tissues / bigger total surface area;veins carry blood back to the heart / from the tissues;veins have thinner walls because the pressure is low / to allow them to be squeezed;veins have fewer muscle / elastic fibres because there is no pulse / because pressure is low;veins have valves to prevent backflow; [9 max]
Which is the correct sequence of events in a heart beat?
atria contract > ventricles contract > AV valves close > semi-lunar valves open
The human circulatory system is structured to serve the organs and tissues of the body efficiently. Explain how circulation of the blood to the lungs and to other systems is separated in humans and what the advantages of this separation are. [8]
b. heart is a double pump / heart has separate pumps for lungs and other systems / leftand right sides of heart are separate / no hole in heart (after birth)c. deoxygenated blood pumped to the lungs and oxygenated to otherorgans/tissues/whole body (apart from lungs) d. each side of the heart has an atrium and a ventricle e. left ventricle/side pumps blood to the systems/tissues and right ventricle/side pumpsblood to the lungs f. left atrium receives blood from the lungs and right atrium receives blood fromsystems/tissues g. left ventricle pumps blood via the aorta and right ventricle pumps blood via thepulmonary artery h. left atrium receives blood via the pulmonary vein and right atrium receives blood viathe vena cava i. lungs require lower pressure blood / high pressure blood would damage lungs j. high pressure required to pump blood to all systems/tissues apart from lungs k. pressure of blood returning from lungs not high enough to continue to tissues / bloodhas to be pumped again after returning from lungs l. oxygenated blood and deoxygenated blood kept separate / all tissues receive bloodwith high oxygen content/saturation
The term to "flex" means to
bend
name given to collection of cells which implants into the womb
blastocyst
Memory cells may not survive a lifetime and individuals may subsequently require a
booster shot to maintain immunity
Amylase is used in human digestion. State the function of amylase.[1 mark]
breaks down starch «by hydrolysis» into maltose/disaccharides
In females, the gametes are produced
by the ovaries
small blood vessels
capillaries
arteries and veins
capillaries connect ___ to ___
Synovial joints are
capsules that surround the articulating surfaces of two bones (i.e. where the bones connect)
Neurotransmitters are
chemical messengers released from neurons and function to transmit signals across the synaptic cleft
Ventilation maintains
concentration gradients of oxygen and carbon dioxide between air in alveoli and blood flowing in adjacent capillaries
Water is produced via
condensation reactions (anabolism)
Describe the mechanism of ventilation in the human lung. [5]
consists of inhaling and exhaling air / exchanging stale air with fresh air (with theenvironment);external intercostal muscles contract moving the rib cage up/out;diaphragm contracts;increases volume of thorax / lowers lung pressure relative to air pressure / pullsair in;diaphragm relaxes;abdominal muscles contract;internal intercostal muscles contract moving the rib cage down/in;force air out / decreases volume of thorax / raise lung pressure relative to air pressure;
Cell Respiration
controlled release of energy (in the form of ATP) from organic compounds e.g glucose and fatty acids in cells. Cells will require oxygen and release carbon dioxide.
The nervous system
converts sensory information into electrical impulses in order to rapidly detect and respond to stimuli
Here is a typical graph derived from a spirometer. Typical questions would include: 1. How many breath were taken in the first 60 seconds?
count the number of peaks or troughs
When the volume of the thoracic cavity increases, pressure in the thorax
decreases
The main muscle that allows us to breathe is the _____.
diaphragm. Contraction of the diaphragm muscle expands the lungs during inhalation when one is breathing air in. It is found underneath the lungs.
The walls of the alveoli actually share a membrane with the capillaries (that's how close they are) and this allows for
diffusion of O and CO2 between the respiratory system and bloodstream.
As a consequence of this more potent immune response, disease symptoms
do not develop (individual is immune to pathogen)
In vitro fertilisation (IVF) refers to fertilisation that occurs outside of the body (in vitro = 'in glass'). It involves using
drugs to suspend normal ovulation (down regulation), before using hormone treatments to collect multiple eggs (superovulation)
Neurons transmit
electrical impulses
Data Based Q's: Polio incidence in 2012 This figure provides data about polio incidence in the three countries where wild polio was endemic as of mid-2012. Define the term "endemic" (1)
endemic = native to the area
In the human digestive system nutrients are absorbed by the:
epithelium, which is the single layer of cells forming the inner lining of the mucosa.
Red blood cells
erythrocytes
The kidney contains specialised structures called nephrons which function to
filter the blood and eliminate wastes
duodenum
first part of the small intestine (adds chemicals from pancreas & proteins from gall bladder).
pulmonary circulation
flow of blood from the heart to the lungs and back to the heart
In the intestines, vesicles commonly form around
fluid containing dissolved materials (pinocytosis - cell 'drinking').
There are four key events that comprise a typical menstrual cycle:
follicular phase, ovulation, luteal phase and menstruation
In chemical digestion:
food is broken down by the action of chemical agents (such as enzymes, acids and bile)
Explain the control of glucose levels in the blood. [8]
glucose levels increase in blood after eating;pancreas cells monitor glucose levels;beta cells (of the islets) in the pancreas detect high glucose levels;produce insulin;causes cells to take up glucose (for energy use);excess stored in liver/muscle as glycogen;decreases glucose levels;low glucose levels stimulate alpha (islet) cells in the pancreas;produce glucagon;stimulate the release of glucose from liver/breakdown of glycogen;raises glucose levels;normal levels of glucose maintained by homeostatic / negative feedback mechanisms; [8 max
Excess glucose brought to the liver from the small intestine is converted to:
glycogen under the direction of the hormone insulin.
hormone released by the embryo in large amounts in the first weeks of pregnancy
hCG
term meaning having one copy of each chromosome
haploid
Allergies are reactions by the immune system to substances in the environment that are normally
harmless, such as pollen, bee stings or specific foods, for example peanuts.
Outline how the rate at which the heart beats is controlled. [6]
heart cells can contract on their own / myogenic (muscle contraction);contractions/heart beat controlled by/starts at pacemaker/sinoatrial node;pacemaker/sinoatrial node is in the wall of the right atrium;signal to contract transmitted from across the atria/heart muscle/heart wall;nerves/impulses from medulla (of brain) to heart;fone nerve increases rate and another nerve decreases it;epinephrine/adrenalin increases rate;[6 max]Reject noradrenalin.Details of events in the cardiac cycle are not relevant and should notberewarded.Do not award marks for reference to the autonomic, sympatheticorparasympathetic nervous systems as these are Option E topics.
The volume of air remaining in the lungs of a person with emphysema after they have exhaled will be
higher than that of a person with normal lung function. This is due to a loss in lung elasticity. As a result, people with emphysema tend to have shallow breathing (short breaths) as the available volume in their lungs for new inhaled air is low.
The liver maintains
homeostasis (the level of sugar, pH, etc.) of nutrients that have been put into the bloodstream. This means that the level is different before and after entering this organ (the liver).
The stomach also releases a
hormone (gastrin) that regulates stomach secretions.
Oxytocin
hormone. responsible for uterine muscle contractions. During pregnancy you do not want these levels to be high. Hence, during pregnancy, progesterone negatively inhibits oxytocin. Towards the end of pregnancy progesterone levels drop and oxytocin and estrogen levels rise!
Monoclonal antibodies are produced by
hybridoma cells
Water is consumed during
hydrolysis reactions (catabolism)
The loop of Henle maintains
hypertonic conditions in the medulla
The target cells for the hormone leptin is the
hypothalamus region of the brain that controls appetite. Leptin binds to receptors in the hypothalamus triggering changes in nervous transmission in that region. The more adipose cells, the more leptin. The more leptin produced, then the less appetite.
Explain how nerve impulses pass from one neuron to another neuron. [8]
impulse/message/action potential/depolarizationreaches thepre-synaptic membrane;calcium channels open;calcium diffuses into/calcium ions enter (pre-synaptic) neuron;vesicles of neurotransmitter fuse with membrane (of pre-synaptic neuron);release of neurotransmitter by exocytosis;diffusion of neurotransmitter across cleft/synapse;neurotransmitter binds to receptor in (post-synaptic) membrane/neuron;ion channels open and sodium/positively charged ions enter;depolarization/action potential/impulse in post-synaptic neuron/membrane;neurotransmitter broken down by enzymes;[8 max]Apart from point d, acetylcholine or another specific neurotransmitteracceptable in place of neurotransmitter.is
Draw and label a diagram to show the structure of the sarcomere
including Z lines, actin filaments, myosin filaments with heads, and the resultant light and dark bands 1. The H zone is the area only occupied by the thick filaments (myosin) 2. The I bands (light) are the regions occupied by only thin filaments (actin) 3. The A bands (dark) are the regions occupied by both filaments (overlap) 4. The Z lines represent the extremities of a single sarcomere
The body responds to an injected vaccine by
initiating a primary immune response, which results in memory cells being made
The opposite end of the muscle from the anchorage is the ______. Bones and exoskeletons are again used for muscle ____________. Muscle contraction causes the bone or section of exoskeleton forming the __________ to move, together with surrounding tissues.
insertion.
Bloodstream is useful because
it is mainly made from H2O = it is an excellent solvent (polar) for transport, etc.
The disadvantage of myelination is that
it takes up significant space within an enclosed environment
The graph shows data from a small group of infected bats that died during hibernation. The average time interval between hibernation emergence periods and the date of death were recorded using temperature sensors for these bats. Outline the relationship between date of death and the mean interval between hibernation emergence periods.[1 mark]
later date of death with longer/bigger intervals (between hibernation emergence)/with less frequent interruptions (to hibernation) The correlation must be described.
What correctly describes blood entering the pulmonary artery from the heart?
leaves right ventricle; deoxygenated
Bones and exoskeletons can change the size and direction of the force exerted by a muscle, so they act as________
levers.
cells which make testosterone in the testis
leydig
Bones are connected to other bones by
ligaments
Starch can exist in one of two forms -
linear chains (amylose) or branched chains (amylopectin).
The smaller fat droplets are then digested by
lipases released from the pancreas
Thyroxin regulates the body's metabolic rate, so all cells need to respond but the most metabolically active, such as
liver, muscle and brain are the main targets as they are most metabolically active.
Outline the changes that lead to the depolarisation of an axon as an action potential travelsalong a neurone. [5]
local currents / ions diffuse from adjacent depolarised section of axon;resting / membrane potential reduced;voltage-gated ion channels affected;sodium channels open;sodium diffuses in / moves in rapidly;therefore fewer positive charges outside and more inside;inside becomes positive relative to outside;before depolarisation outside was positive relative to inside; [5 max](Award no marks for statements about potassium movement and repolarisation)
Two transport systems
lymphatic and circulatory systems
Digestion of starch is completed by enzymes in the membranes of microvilli on villus epithelium cells:
maltase and dextrinase digest maltose and dextrins into glucose.
Vaccinations induce long-term immunity to specific pathogenic infections by stimulating the production of
memory cells
Water levels within an organism are constantly changing as a result of
metabolic activity
Digestion of starch is completed by enzymes in the membranes of:
microvilli on villus epithelium cells
The villi absorb:
mineral ions and vitamins and also monomers formed by digestion such as glucose.
Antigens on the surface of the influenza virus include
molecules which are necessary for the virus to attach to and later leave a host cell.
Villi absorb
monomers formed by digestion as well as mineral ions and vitamins
Tendons join
muscles to bones.
In some neurons, the axon may be surrounded by an insulating layer known as a
myelin sheath
Some neurons are surrounded by a layer of cells called a
myelin sheath.
There are many _______ in muscles
myofibrils (protein structures that make up muscle fibre)
"muscle" layer in the womb
myometrium
Thyroxin acts on
nearly every tissue in the body and is essential to the proper development and differentiation of cells
Blood is filtered by specialised structures called
nephrons which produce urine
A neuron is the name given to a
nerve cell.
If there is no SRY =
no development of male reproductive system. As such, for XX chromosomes, there will be a lack of the TDF based on no Y chromosome. The lack of TDF will allow the cortex of embryonic gonads to develop in to ovaries, which will then produce estrogen, and lead to the development of other female sexual characteristics.
diastolic pressure
occurs when the ventricles are relaxed; the lowest pressure against the walls of an artery
number of egg cells resulting from oogenesis
one
All animals are either
osmoregulators or osmoconformers
term used to describe the movement of water from fetus to mother or vice versa
osmosis
Glucose monomers can also be generated from the breakdown of
other disaccharides (such as lactose and sucrose)
Substances in these allergens cause
over-activation of basophils and mast cells and therefore excessive secretion of histamine.
Where does sperm meet the egg?
oviduct / fallopian tube = fertilization
Gas exchange is where
oxygen that we have breathed in is moved into the bloodstream for cells to take up, and where carbon dioxide shifts from the bloodstream into the lungs, so that it can be breathed out.
A deposit of fatty material on the inner lining of an arterial wall
plaque
component of the blood in which you would find dissolved FSH
plasma
Activated B cells multiply to form clones of
plasma cells and memory cells
When a specific B lymphocyte is activated following antigen presentation, it divides into
plasma cells and memory cells
Blood is a liquid tissue containing glucose, urea, plasma proteins and other components.List the other components of blood. [5]
plasma/water; dissolved gases / CO2 / O2; erythrocytes / red blood cells; leucocytes / white blood cells; lymphocytes and phagocytes; platelets; hormones / named hormone(s); amino acids / albumin / antibodies; salts / minerals / ions other named solute in plasma apart from glucose, urea and plasma proteins; [5 max]
name given to small cell which results from unequal meiotic division during egg formation (2 words)
polar body
Testosterone causes
pre-natal development of male genitalia and both sperm production and development of male secondary sexual characteristics during puberty
If a person receives a blood transfusion they will
produce antibodies against any antigens that are not ordinarily in their body. These antibodies will cause significant and potentially fatal health problems as antibodies attach to the red blood cells and clump together the donated blood cells.
State one possible use of hybridoma cells.[1 mark]
produce monoclonal antibodies OR diagnosis of diseases/malaria/cancer/HIV OR treatment of rabies OR blood and tissue typing OR pregnancy testing OR targeting of cancer cells «with a chemotherapy drug» OR treatment of infection if too late for vaccination/successful immune response Only accept the first use of hybridoma cells given in the answer Not treatment of malaria
State the role of plasma cells in the immune system.[1 mark]
produce/secrete antibodies
Myelin is a mixture of
protein and phospholipids that is produced by glial cells (Schwann cells in PNS; oligodendrocytes in CNS)
All living organisms have proteins and other substances in the plasma membranes on the surface of their cells, especially proteins. Some organisms have a cell wall outside their plasma membranes made of polysacchandes or other substances. There is so much variety in the types of substance on the surfaces of cells that every species has unique molecules. Viruses are not considered living organisms and are not composed of cells, but they also have unique molecules on their surface. The surface of most viruses is a
protein coat (capsid). The capsid of some viruses is enveloped in a membrane taken from the plasma membrane of the host cell The image below shows the capsid of an adenovirus.
Digestion of starch is completed by enzymes in the membranes of microvilli on villus epithelium cells: maltase and dextrinase digest maltose and dextrins into glucose. Also in the membranes of the microvilli are:
protein pumps that cause the absorption of the glucose produced by digesting starch.
The basement membrane is a
protein structure that maintains the shape and integrity of the single layer of cells on either side.
What route does blood follow to supply oxygen to heart muscle after leaving the capillary bed of the lungs?
pulmonary vein > left atrium > left ventricle > aorta > coronary artery
ADH controls
reabsorption of water in the collecting duct
The faeces is stored in the:
rectum and eliminated out the anus
The hormones insulin and glucagon
regulate the concentration of glucose in the bloodstream (controls availability to cells)
Leptin is a hormone produced by adipose cells that
regulates fat stores within the body by suppressing appetite
When presynaptic neurons are depolarized they
release a neurotransmitter into the synapse
Melatonin is
secreted by the pineal gland to control circadian rhythms ("Circa" for approximate and "dia" is the Latin for day).
As the DNA condense each homologous chromosome
seeks the other (mom & dad --> they are in the same position).
But mom's and baby's blood is
separated, because the mother has a higher blood pressure = capillaries of baby would burst.
Meiosis only happens in
sex cells; you are made up of mixtures from your mom & dad gonads = egg cells and sperm cells to make your genetically unique (egg / sperm cells)
Describe how skin and mucous membranes act as barriers. [5]
skin is a physical barrier/impermeable;skin has an acidic pH which inhibits growth of (pathogenic) bacteria);outer layer flaked off (to remove parasites/bacteria);mucous membranes trap microorganisms;lysozyme secreted and destroys bacteria;cilia push mucus containing bacteria out;other/beneficial bacteria on skin keep other pathogens in check; [5 max]
Because of the ______, amylase cannot break the 1,6 bonds in amylopectin.
specificity of its active site
term used to describe the formation of sperm
spermatogenesis
literally means "parent of sperm". Singular spelling of the word.
spermatogonium
To "extend" means to
straighten.
Epidemiology is the
study of the patterns, causes and effects of health and disease conditions in a defined population
The muscles responsible for exhaling are
the abdominal muscles and internal intercostals (plus some accessory muscles)
The structure of the cells of the epithelium of the villi are adapted to:
the absorption of food.
Gas exchange is the delivery of oxygen from the lungs into the bloodstream and the elimination of CO2 from the bloodstream to the lungs. It occurs in the lungs, more specifically
the alveoli and in a network of capillaries located in the walls of the alveoli. Here you see red blood cells travelling through the capillaries.
The kidney functions as
the blood's filtration and water balancing system - it removes metabolic wastes for excretion
Diabetes is caused by
the body either not producing insulin (Type I) or failing to respond to insulin production (Type II)
The myelin sheath improves
the conduction speed of electrical impulses along the axon, but require additional space and energy
So when a muscle contracts:
the dark bands stay the same size (the region where you find the myosin), the light bands get shorter and the sarcomere (region from between 2 Z-lines --> M line/region also gets smaller). --> BECAUSE OF THE OVERLAPPING of the two sheaths.
Neurotransmitters are released in response to
the depolarisation of the axon terminal of a presynaptic neuron
The muscles responsible for inhaling are
the diaphragm and external intercostals (plus some accessory muscles)
A resting potential is
the difference in charge across the membrane when a neuron is not firing
If we don't ventilate our lungs
the diffusion gradient becomes much smaller and the amount of gas exchange slows down.
Gas Exchange
the diffusion of O2 from the alveoli to the blood and CO2 from the blood to the alveoli.
Histamine is secreted in response to local infection and causes
the dilation of the small blood vessels in the infected area = the vessels become leaky, increasing the flow of fluid containing immune components to the infected area and allowing these components to leave the blood vessel, resulting in both specific and non-specific immune responses.
The type of nitrogenous waste in animals is correlated with:
the evolutionary history of the animal and the habitat
The hydrolysis of maltose / dextrin results in
the formation of glucose monomers.
Blood carrying glucose and other products of digestion flows though villus capillaries to venules in the submucosa of the wall of the small intestine. The blood in these venules is carried via:
the hepatic portal vein to the liver, where excess glucose can be absorbed by livercells and converted to glycogen for storage.
Leptin is secreted by cells in adipose tissue and act on
the hypothalamus of the brain to inhibit appetite
myocardial infarction
the occlusion of one or more coronary arteries caused by plaque buildup (heart attack)
Villi increase
the surface area of epithelium over which absorption is carried out.
Meiosis
to go from diploid to haploid cell
The main purpose of the myelin sheath is
to increase the speed of electrical transmissions via saltatory conduction
The larynx flows in to the ______.
trachea or "windpipe". The trachea is a tube that carries air to the lungs. It is strengthened by rings made of cartilage, so that it doesn't collapse.
The ultrastructure of the glomerulus and Bowman's capsule facilitate
ultrafiltration
Blood Group O are also considered to be
universal donor (they can give blood to anybody), because every blood group has antigens on the red blood for O, hence it will not trigger a reaction against this transfusion.
Blood Group AB are also considered to be
universal recipients (they can receive any blood group, because they have antigens to all).
Here is a typical graph derived from a spirometer. Typical questions would include: 7. During exercise the breathing rate and the volume of inhaled/exhaled air will go
up when compared to tidal volumes and the peaks will be higher than before and closer together than before.
When you breath out air enters the space labelled "Pure oxygen in the box chamber" and the pen moves
upward. (The pen traces a line on a rotating sheet of graph paper. The rotating paper moves at a known speed.)
Explain the role of antibody production with regard to vaccinations. [8]
vaccine injected into body / ingested;containing killed / weakened pathogen / fragments of pathogen / toxins;macrophages ingest antigen / antigen presenting cells ingest antigen;T-helper cells bind to macrophages;T-helper cells stimulated / activated;antigen binds to B-cells;activated T-helper cells then bind to B-cells;activation of B-cells;which divide / undergo mitosis to form clones of (plasma) cells;B-cells / plasma cells produce antibodies;memory cells produced;second / booster shot sometimes given;stimulates memory cells;more antibodies and faster response / graph to show this;antibodies are specific to antigen; [8 max]
umbilical ... The blood vessel which travels from the placenta back to the baby
vein
What is the correct sequence of blood flow in normal human circulation?
vena cava > right atrium > pulmonary vein > aorta
Describe the structure of the ventilation system, including the alveoli. [8]
ventilation occurs within the lungs;trachea divides to form two bronchi;bronchi divide to form bronchioles;several divisions of bronchioles;alveoli connected to bronchioles;trachea/bronchi/bronchioles/airways lined with cilia/ciliated epithelium;diaphragm and intercostal muscles;trachea/bronchi have rings/c-shaped pieces of cartilage;alveolus is an (air) sac;very small / diameter is (about) 100μm;many alveoli so large total surface area;wall of alveolus is a single layer of cells;cells in alveolus wall are very thin;surrounded by a network of capillaries;some (larger) cells in the wall secrete fluid/surfactant/natural detergent;Award any of the above points if clearly drawn in a diagram. [8 max]
Exercise will increase both
ventilation/breathing rate and also pulse rate.
Alveoli are
very thin and moist, so that oxygen and carbon dioxide can quickly and easily move through them, into or out of the blood.
The small intestine contain infoldings called:
villi, to increase surface area and optimise the rate of absorption
The surface area of epithelium is further increased by the presence of:
villi, which are small projections of the mucosa on the inside of the intestine wall.
blood transfusion
whole blood or cells are taken from a donor and infused into a patient
Once you generate an action potential -
you can propagate an action potential down along the axon of a motorneuron.
Sinoatrial Node
-SA node or the SAN -the primary pacemaker for the hear and controls the rate at which the heart beats -60-100 heartbeats per minute
Heart structure: heart valves
- Atrioventricular valves (between atria and ventricles): bicuspid valve on the left side; tricuspid valve on the right side. Semilunar valves (between ventricles and arteries): aortic valve on the left side; pulmonary valve on the right side.
Adaptations to the loop of Henle
- Frogs and toads have almost no loop of Henle; it helps with reabsorption of water and frogs / toads have more access to water. - Kangaroo rats have very long loops of Henle and recycle nearly all of their water, because they live in desert climates.
The Malpighian tubule system in insects and the kidney carry out osmoregulation and the removal of nitrogenous wastes.
- In mammals, the excretory system (kidneys) is separate from the digestive system of the animal. - In insects, the excretory system (Malpighian tubules) connects to the digestive system of the animal. - Insects have a circulating fluid system called hemolymph that is analogous to the blood system in mammals. - Malpighian tubules branch off from the intestinal tract and actively uptake nitrogenous wastes and water from the hemolymph. - The tubules pass these materials into the gut to combine with the digested food products. - Solutes, water, and salts are reabsorbed into the hemolymph at the hindgut, whereas nitrogenous wastes (as uric acid) and undigested food materials are excreted via the anus.
The heart rate can be increased or decreased by impulses brought to the heart through two nerves from the medulla of the brain (2).
- Nerve signals from the brain can trigger rapid changes, while endocrine signals can trigger more sustained changes. - Changes to blood pressure levels or CO2 concentrations (and thereby blood pH) will trigger changes in heart rate.
The muscle and elastic fibers assist in maintaining blood pressure between pump cycles.
- The muscle fibers help to form a rigid arterial wall that is capable of withstanding the high blood pressure without rupturing. - Muscle fibers can also contract to narrow the lumen, which increases the pressure between pumps and helps to maintain blood pressure throughout the cardiac cycle. - The elastic fibers allow the arterial wall to stretch and expand upon the flow of a pulse through the lumen. - The pressure exerted on the arterial wall is returned to the blood when the artery returns to its normal size. - The elastic recoil helps to push the blood forward through the artery as well as maintain arterial pressure between pump cycles.
Heart structure: chambers
- Two atria: smaller chambers near the top of heart that collect blood from body and lungs. -bTwo ventricles: larger chambers near the bottom of heart that pump blood to body and lungs.
Enzymes
-are biological catalysts which speed up the rate of a chemical reaction by lowering activation energy -enzymes allow the digestive processes to occur at body temperatures and sufficient speeds for survival -enzyme substrate specificity allows for the digestion of certain molecules independently as well as in distinct locations
William Harvey's findings
-arteries and veins were part of a single connected blood network -arteries pumped blood from the heart to the lungs and body tissues -veins returned blood to the heart (from the lungs and body tissues)
Glucagon
-increases blood glucose levels by limiting the synthesis and storage of glycogen by the liver and adipose tissues
Pancreas
-produces a broad spectrum of enzymes that are released into the small intestine via the duodenum - secretes hormones like insulin and glucagon which regulate blood sugar concentrations -amylase, lipase, endopeptidase, nuclease, biocarbonate ions (they neutralize stomach acid in the small intestine
Arteries
-they convey blood at high pressure from the ventricles to the tissues of the body -arteries have muscle cells and elastic fibers in their walls -arteries take blood from the ventricles to the tissues of the blood
Artery structure
-they have a narrow lumen and maintain a high blood pressure (80-120) -have a thick wall that contains an outer layer of collagen to prevent the artery from rupturing -the arterial wall also has an inner layer of muscle and elastic fibers to help maintain pulse flow
Capillary Structure
-very small diameter (5 um wide) which only allow one red blood cell at a time -capillary wall is made up of a single layer of cells to minimize the diffusion distance for permeable materials -they are surrounded by a basement membrane which is permeable to necessary materials -some have pores to further aid in the transport of materials between tissue fluid and blood
Osmosis
-water molecules will diffuse across the membrane in response to the movement of ions and hydrophilic monomers -this occurs in both the small an large intestine water
The ultrastructure of the glomerulus and Bowman's capsule facilitate ultrafiltration (5).
1. An afferent arteriole (small branch of the renal artery) brings unfiltered blood into the kidney. 2. It branches into the glomerulus; the glomerulus is FENESTRATED, meaning it has small slits that open when pressure is high. 3. The pressure is high in the glomerulus because the efferent arteriole has a smaller diameter than the afferent arteriole. 4. Ultrafiltration is the process by which substances are filtered out of the glomerulus under unusually high blood pressure, becoming filtrate. 5. Small substances make it through the basement membrane, while large substances like cells and proteins leave via the efferent arteriole.
The difference in the structural characteristics of arteries, capillaries, and veins is attributable to their respective functions (3).
1. Arteries have thick walls and narrow lumens because they transport blood at high pressure. 2. Capillaries have walls that are only a single cell thick because they exchange materials between blood and tissue. 3. Veins have thin walls with wide lumens and valves because they transport blood at low pressure.
The cardiac cycle describes the series of events that take place in the heart over the duration of a single heartbeat. It is comprised of a period of contraction (systole) and relaxation (diastole) (3).
1. Atrial systole: Atrium contracts; blood flow from the atrium to ventricle; AV valves open and aortic valves closed. 2. Ventricular systole: Ventricle contracts; blood flow from ventricle to aorta; AV valves closed and aortic valves open. 3. Diastole: Blood flows into atrium and ventricle; AV valves open and aortic valves closed.
Alcohol and liver damage (3):
1. Cirrhosis: destroys hepatocytes and leaves scar tissue. 2. Fatty liver: damaged areas build up fat instead of liver tissue. 3. Inflammation: the liver swells; alcoholic hepatitis.
Liver: carbohydrate metabolism
1. Excess carbs and proteins converted to fatty acids and triglycerides. 2. Synthesizes phospholipids and cholesterol. 3. These are stored or transported by lipoproteins. 4. Low-density lipoproteins (LDL, or "bad" cholesterol) transports cholesterol to body cells. 5. High-density lipoproteins (HDL, or "good" cholesterol) transports excess cholesterol back to the liver. 6. Excess cholesterol is converted into bile salts, which can be excreted.
Liver: fat metabolism (4)
1. Liver monitors levels of glucose in blood. 2. When blood sugar is high, INSULIN from the pancreas (endocrine function --> releases this hormone via the bloodstream) causes the liver to store glucose as glycogen. 3. When blood sugar is low, GLUCAGON from the pancreas causes the liver to hydrolyze glycogen and release glucose. 4. The liver stores excess vitamin A and D.
Maintaining blood pH
1. Many H ions temporarily bind to plasma proteins, taking them out of solution. 2. Ventilation rate controlled by MEDULLA OBLONGATA. 3. Chemosensors in the inner wall of the aorta and carotid arteries detect an increase in CO2 levels. 4. They send action potentials to the medulla's breathing center. 5. The medulla sends messages to the diaphragm and internal intercostal muscles, increasing frequency. 6. The opposite happens when CO2 levels drop; vagus nerve decreases heart rate.
Loop of Henle (4)
1. Much of the water is still left after the proximal convoluted tubule and enters the loop of Henle. 2. This loop dips into the renal medulla (BOTTOM of loop; renal cortex is top of loop), which is salty (AKA hypertonic). 3. The DESCENDING portion is permeable to water, but not relatively impermeable to salt ions; water leaves and gets reabsorbed. 4. The ASCENDING portion is impermeable to water, but permeable to salt ions; salt ions get pumped (active transport) out the tubule and reabsorbed.
Gas exchanges in alveoli
1. Oxygen and CO2 both diffuse down concentration gradient; blood in pulmonary artery is relatively low in O2 and high in CO2, so O2 moves into the capillary beds and CO2 moves into the alveoli. 2. Alveoli are only one cell thick for diffusion.
Reabsorption
1. Starts at the proximal convoluted tubule; made up of a single ring of cells; surrounded by peritubular capillary bed where those items get reabsorbed back into the blood; MICROVILLI along inside increase surface area. 2. Most of the salt ions begin getting reabsorbed in the proximal convoluted tubule via active transport into tubule cells and intercellular fluid outside tubule. 3. Water gets reabsorbed following movement of salt through osmosis (going from hypotonic to hypertonic solution). 4. All glucose in filtrate is reabsorbed back into bloodstream via active transport.
Steps of inhalation
1. The DIAPHRAGM contracts (flattens downwards) as the EXTERNAL INTERCOSTAL MUSCLES and one set of abdominal muscles help raise the ribcage, increasing the volume of the thorax. 2. Because the volume increases, pressure decreases. 3. Due to low pressure, volume of lung tissue increases (attached to thorax). 4. Decrease in pressure inside lungs. 5. Air comes in through open mouth or nasal passages and fills alveoli. 6. Air travels through trachea > bronchi > bronchioles > alveoli.
Steps of exhalation
1. The DIAPHRAGM relaxes and curves upwards. 2. The EXTERNAL INTERCOSTAL MUSCLES relax, allowing the ribs to fall. 3. The INTERNAL INTERCOSTAL MUSCLES contract, pulling the rips downwards. 4. The volume of the thoracic cavity and lungs decreases, causing air to flow out of the lungs.
The proximal convoluted tubule selectively reabsorbs useful substances by active transport (3).
1. The proximal convoluted tubule has a microvilli cell lining to increase the surface area for material absorption from the filtrate. The tubule is a single cell thick and connected by tight junctions, which function to create a thin tubular surface with no gaps. 2. There are also a large number of mitochondria within these tubule cells, as reabsorption involves active transport. 3. The tubules reabsorb all glucose, amino acids, vitamins and hormones, along with most of the mineral ions (~80%) and water.
Heart muscle contraction
1. The sinoatrial (SA) node sends an impulse at regular intervals, causing contractions of both atria. 2. The atrioventricular (AV) node receives signal from SA, delays slightly, then sends out another signal that contracts the ventricles. 3. The electrical impulse travels through conducting fibers and then through the Purkinje fibers. (bundle of His, intercolated discs...)
The electrical conduction of a heartbeat occurs according to the following events (4):
1. The sinoatrial node sends out an electrical impulse that stimulates contraction of the myocardium (heart muscle tissue). 2. This impulse directly causes the atria to contract and stimulates another node at the junction between the atrium and ventricle. 3. This second node - the atrioventricular node (AV node) - sends signals down the septum via a nerve bundle (Bundle of His). 4. The Bundle of His innervates nerve fibers (Purkinje fibers) in the ventricular wall, causing ventricular contraction. *This sequence of events ensures there is a delay between atrial and ventricular contractions, resulting in two heart sounds. This delay allows time for the ventricles to fill with blood following atrial contractions so as to maximize blood flow.
Capillaries have specialized structures in order to accomplish their task of material exchange (4).
1. They have a very small diameter (~ 5 µm wide) which allows passage of only a single red blood cell at a time (optimal exchange). 2. The capillary wall is made of a single layer of cells to minimize the diffusion distance for permeable materials. 3. They are surrounded by a basement membrane which is permeable to necessary materials. 4. They may contain pores to further aid in the transport of materials between tissue fluid and blood.
Veins collect blood at low pressure from the tissues of the body and return it to the atria of the heart. They have a specialized structure in order to accomplish this (3).
1. They have a very wide lumen (relative to wall thickness) to maximize blood flow for more effective return. 2. They have a thin wall containing less muscle and elastic fibers as blood is flowing at a very low pressure (~ 5 - 10 mmHg). 3. Because the pressure is low, veins possess valves to prevent backflow and stop the blood from pooling at the lowest extremities.
ADH & reabsorption
1. Total amount of water eliminated depends on factors like amount of water taken in, perspiration rate, and ventilation rate. 2. The filtrate that enters a collecting duct is dilute urine; it is still hypotonic to the interstitial fluid of the medulla. 3. The COLLECTING DUCT changes in permeability to water in the presence or absence of ANTIDIURETIC HORMONE (ADH). 4. ADH is released from the posterior lobe of the pituitary gland, travels through the blood, and targets the collecting ducts. 5. If ADH is present, the collecting duct becomes permeable to water and more water is reabsorbed (due to dehydration). Less pee. 6. If ADH is not present, collecting ducts are impermeable to water and it remains in the urine.
Nephrons filter blood and then reabsorb useful materials from the filtrate before eliminating the remainder as urine. This process occurs in three key stages:
1. Ultrafiltration - Blood is filtered out of the glomerulus at the Bowman's capsule to form filtrate. 2. Selective reabsorption - Usable materials are reabsorbed in convoluted tubules (both proximal and distal). 3. Osmoregulation - The loop of Henle establishes a salt gradient, which draws water out of the collecting duct.
Which features of alveoli make them well suited to gas exchange? I. Dense arterial network II. Moist lining III. Walls consisting of a single layer of flattened cells a. II and III only b. I, II and III c. I and II only d. I and III only
A
Which one of these statements about lungs is false? a. The concentration of CO2 is higher in the air than in the alveolar capillaries. b. Gas exchange takes place across moist membranes. c. The total exchange surface area is relatively large. d. The lining of the alveoli is only one cell thick. e. The gases move across the exchange membranes by diffusion.
A
Hepatic circulation
Hepatic artery: delivers oxygen-rich blood from the heart to the liver. Hepatic portal vein: delivers nutrient-rich blood from the intestine to the liver. Hepatic vein: takes deoxygenated blood from the liver back to the right atrium of the heart via the inferior vena cava.
Nutrient stored by liver: iron
Iron is removed from hemoglobin, and later sent to bone marrow.
Sequence of blood vessels from heart
Large artery > smaller artery branches > arteriole > capillary bed > venule > larger veins > large vein which takes blood back to the heart
How the ultrastructure of the glomerulus and Bowman's capsule facilitate ultrafiltration (TL;DR):
The glomerulus is fenestrated; the efferent arteriole has a smaller diameter than the afferent arteriole which causes high pressure, and has lots of mitochondria for active transport of mitochondria. The Bowman's capsule has a basement membrane, gaps between cells, and is one cell thick; can diffuse a lot.
Atherosclerosis
The hardening and narrowing of the arteries due to the deposition of cholesterol. - Fatty deposits develop in the arteries and significantly reduce the diameter of the lumen. - The restricted blood flow increases pressure in the artery, leading to damage to the arterial wall. - The damaged region is repaired with fibrous tissue which significantly reduces the elasticity of the vessel wall. - As the smooth lining of the artery is progressively degraded, plaque forms. - If the plaque ruptures, blood clotting is triggered, forming a thrombus that restricts blood flow. - If the thrombus is dislodged it becomes an embolus and can cause a blockage in a smaller arteriole, leading to cardiac arrest or stroke.
The composition of blood in the renal artery is different from that in the renal vein (4).
The kidney contains specialized structures called nephrons which function to filter the blood and eliminate wastes. Consequently, the composition of blood entering the kidney (via renal artery) differs to that exiting the kidney (via renal vein). Blood in the renal vein (i.e. after the kidney) will have: 1. Less urea (large amounts of urea is removed via the nephrons to form urine). 2. Less water and solutes / ions (amount removed will depend on the hydration status of the individual). 3. Less glucose and oxygen (not eliminated, but used by the kidney to generate energy and fuel metabolic reactions). 4. More carbon dioxide (produced by the kidneys as a by-product of metabolic reactions).
systemic circulation
circulation that supplies blood to all the body except to the lungs
Arteries have ____ pressure and veins have ____ pressure.
high; low
(look at y-axis: volume (ml/kg) - if the person were 50 kg, how much ml of air would they breath in?
= 350ml --> 37-30 = 7ml per kg --> 7ml per 50kg --> 7*50 = 350
What is this person's breathing rate (per minute) when they are at rest?
= how many breaths you take per minute. = 60 / 5 = 12*2 = 24 breaths per minute (when calculating the breaths you just look at the peaks (because they involve in and out) & (the others are a big breath inward and outward - not at rest))
Blood group O person will react to blood types containing
A and/or B antigens ............Blood Group A, B or AB. However they can give blood to anyone..........universal donor.
haploid cell
A cell containing only one set of chromosomes (n) = just half.
How does a gene determine Sex Development?
A gene on the Y chromosome causes embryonic gonads to develop as testes and secrete testosterone
Water conservation can be improved by having a longer loop of Henle, which increase the salt gradient in the medulla:
A greater the salt gradient in the medulla means more water is reabsorbed by the collecting ducts and urine is concentrated
A)True
A myeloma cell is a cancer cell that grows continuously. A)True B)False
1. Reduced supplies of oxygen and nutrients to heart muscles downstream. 2. Pain due to lack of oxygen may result, a condition called angina. 3. If the covering of the fatty build up (atheroma/plaque) breaks open, then the resulting formation of a blood clot can block the artery and cause severe consequences.
A narrowed artery will result in:
build up of triglycerides, LDL, cholesterol, calcium and the remains of white blood cells beneath the endothelium/inner layer of the blood vessel. The hardening of this plaque with calcium gives rise to a condition called atherosclerosis - the "sclerosis" means "hardening").
A plaque or atheroma (for the Greek for porridge/gruel) in an artery is a
Discuss the cause, transmission and social implications of AIDS............social implications not required anymore [8]
AIDS caused by HIV;penetrates (T) lymphocytes;(envelope) (glyco)protein and cell receptors involved;reverse transcriptase enables DNA to be producedfrom viral RNA; (reject DNA transformedinto RNA)number of lymphocytes reduced over years;results in lower immunity;other illnesses develop (as result of lower immunity);AIDS is the observed syndrome when final stages of infection develop / OWTTE;transmission: [3max]HIV transmitted through blood/sexual contact/body fluids/placenta/childbirth/ breastfeeding;distribution/transmission uneven around the world;transmission risk increased depending on society's traditions/beliefs/behaviour;(rare minority of) individuals do not have cell receptors and do not develop AIDS;condoms/latex barriers only protection against transmission through sexual contact;social implications: [3max]treatment expensive;discrimination against victims;moral obligation of wealthy countries to help poorer countries;economic consequences / loss of wage earners etc.;increase in the number of orphans;comment on traditions/beliefs/behaviour; (if not already awarded in transmission) [8 max]
Acetylcholine only binds to
Acetylcholine only binds to postsynaptic membrane receptors for a short time allowing for the initiation of one action potential.
What do you call this change in potential?
Action potential (that is the pulse of electricity).
Discuss the ethical issues associated with IVF
Advantages of IVF 1. Chance for infertile couples to have children 2. Genetic screening of embryos could decrease suffering from genetic diseases 3. Spare embryos can be stored for future pregnancies or used for stem cell research Disadvantages of IVF 1. IVF is expensive and might not be equally accessible to all 2. Success rate is low (~15%) and therefore stressful for couples 3. It could lead to eugenics (e.g. gender choice) 4. Often leads to multiple pregnancies which may be unwanted, unable to be budgeted for and involves extra birth risks 5. Issues concerning storage and disposal of unused embryos (right to life concerns) 6. There are cultural and religious objections to embryo creation by such means 7. Inherited forms of infertility may be passed on to children
After day 14 the levels of FSH and LH fall. i) What effect does this have in the ovary?
Allows the production of progesterone from the corpus luteum
Structure of an Alveolus
Alveoli function as the site of gas exchange, and hence have specialised structural features to help fulfil this role: 1. They have a very thin epithelial layer (one cell thick) to minimise diffusion distances for respiratory gases 2. They are surrounded by a rich capillary network to increase the capacity for gas exchange with the blood 3. They are roughly spherical in shape, in order to maximise the available surface area for gas exchange 4. Their internal surface is covered with a layer of fluid, as dissolved gases are better able to diffuse into the bloodstream
Why would an action potential not happen in area 3 in this diagram picture?
An action potential will not be generated in area 3 of the image because area 3 is not in resting potential. It is hyperpolarised from the previous action potential. This is why the impulse only moves in one direction.
Most severe type of histamine mediated allergic response:
Anaphylactic shock (histamine induced massive overreaction that can kill you in a couple of minutes, which is why people carry around epipens containing adrenaline.
All animals need to maintain an appropriate water balance, however the need for water conservation will depend on habitat:
Animals in arid, desert environments will need more efficient water conservation than animals in moist, mesic environments
1. Pathogens with antigens on their surface invade the body. This is called the "challenge" stage. 2. Pathogen is ingested by a phagocyte and an antigen from the pathogen is displayed on the phagocyte plasma membrane. 3. A lymphocyte (with an antibody in its plasma membrane that matches the antigen) binds the antigen which is displayed on the phagocyte surface. 4. This activates that particular lymphocyte which begins B cells to divide by mitosis to produce a clone of cells called plasma cells. This is called clonal selection. These cells become large due to extra cytoplasmic volume and contain a very extensive rER. Large amounts of antibodies are secreted through vesicles via exocytosis. 5. Antibodies neutralise the pathogen 6. Some antibody producing cells remain as memory cells which persist and allow a rapid (secondary) response if the pathogen is encountered again. Memory cells give long term immunity.
Antibody production:
1. Lymphocytes enlarge with rER, Golgi Apparatus, mitochondria, etc. and form plasma cells (enlarged lymphocytes). 2. Plasma cells secrete large quantities of proteins called antibodies in response to being presented specific substances called antigens on pathogens and these in turn can no longer enter cells.
Are plasma cells lymphocytes?
Discuss whether the data in the graph show that there is a causal link between the date of death and the interval between hibernation emergence periods. [2 marks]
Arguments for a causal link a. there is a trend/correlation/relationship (shown by the data in the graph) b. explanations of how more frequent emergence from hibernation could cause earlier death (are plausible)/example of an explanation Arguments against a causal link c. there is a correlation but this does not show a causal link / correlation does not prove causation d. more data/further research is needed to show the causes e. there is (much) variation/spread in the data f. other factors can affect the date of death
Arteries convey blood pumped out at high pressure by the ventricles of the heart. They carry the blood to tissues of the body.
Arteries Diagram
Arteries convey blood at high pressure from the ventricles to the tissues of the body.
Arteries convey blood at high pressure from the _____ to the ______ of the body
thick walls and narrow lumens
Arteries have
Arteries have muscle cells and elastic fibres in their walls
Arteries have _____ and ______ in their walls
blood flow to cardiac muscle is restricted, causing chest pain and minerals often become deposited in the plaque making it hard and rough.
As Coronary artery disease becomes more severe
Atherosclerosis is the hardening and narrowing of the arteries due to the deposition of cholesterol
Atherosclerosis
State the source, substrate, products and optimum pH for any two named digestive enzymes.[4]
Award [1] for each two of the following correct: name, source, substrate, product(s),and optimum pH.e.g. name: amylase; (Do not accept the general term protease.)source: pancreas / salivary gland;substrate: starch; (Do not accept carbohydrate.)product: maltose;optimum pH: 7 / slightly alkaline; [4 max]Similarly, for second enzyme.
Explain the mechanism of ventilation of human lungs.
Award these points either for inspiration or expiration but not both:ventilation is movement of air into and out of lungs; volume of thorax/lungs/chest increased/decreased; pressure in thorax/lungs/chest decreased/increased;air flows from higher to lower pressure / air flows until the pressures are equal;During inspiration/inhalation:external intercostal muscles contract so ribcage moved up/out;diaphragm contracts so moves down/becomes flatter;internal intercostal/abdomen (wall) muscles relax;During expiration/exhalation:external intercostal muscles relax so ribcage moved down/in;diaphragm relaxes;recoil of elastic fibres that stretched during inspiration;internal intercostal muscles contract (during forced ventilation);abdomen (wall) muscles contract (during forced ventilation);[8 max]
What is bone X and muscle Y in the diagram of the elbow joint?
B
And so, a person with: Blood group A person will react to any blood containing
B antigens: Blood Group B or AB.
Which of the following describes arteries? a. They carry blood from the lungs. b. They carry blood towards the heart. c. They have thick muscular walls. d. They usually contain valves.
C
Discuss the benefits and dangers of vaccination
Benefits: 1. Vaccination results in active immunity 2. It can limit the spread of infectious diseases (pandemics / epidemics) 3. Diseases may be eradicated entirely (e.g. smallpox) 4. Vaccination programs may reduce the mortality rate of a disease as well as protect vulnerable groups (e.g. youth, elderly) 5. Vaccinations will decrease the crippling effects of certain diseases (e.g. polio) 6. It will decrease health care costs associated with treating disease conditions Risks: 1. Vaccinated individuals may produce (mild) symptoms of the disease 2. There may be human error in the preparation, storage or administration of the vaccine 3. Individuals may react badly to vaccines (e.g. hypersensitive / allergic reactions) 4. Immunity may not be life long - booster shots may be required 5. There may be possible toxic effects of mercury-based preservatives used in vaccines
ANSWERS: Annotate this ultrastructure of the muscle fibre:
Between two Z lines is a structure called a sarcomere (Greek sarx "flesh", meros "part").
What does the bile contain?
Bile contains bile salts which interact with fat globules and divide them into smaller droplets (emulsification).
_________ are detected in urinary tests
Blood cells, glucose, proteins and drugs
cell bursting
Blood glucose too low = cell bursting
ventricular contraction and flows through the arteries in repeated surges called pulses
Blood is expelled from the heart upon
the protection of the body against pathogens.
Blood plays an important role in
systolic pressure
Blood pressure in the arteries during contraction of the ventricles.
Vena Cava
Body's largest vein:
What is used in an insertion?
Bones and exoskeletons are used for the insertion but these regions move when the muscle contracts.
Comparison of Spermatogenesis and Oogenesis: Which involves two meiotic divisions?
Both
Why is brown fat more abundant in newborns and hibernating animals?
Brown adipose tissue (has more mitochondria) is especially abundant in newborns and in hibernating mammals. It is also present and metabolically active in adult humans, but its prevalence decreases as humans age. Its primary function is thermoregulation.
Comparison of Spermatogenesis and Oogenesis: Which involves growth of cells prior to meiosis?
BOTH GROW
1. Arteries and veins were part of a single connected blood network (he did not predict the existence of capillaries however) 2. Arteries pumped blood from the heart (to the lungs and body tissues) 3. Veins returned blood to the heart (from the lungs and body tissues)
Based on some simple experiments and observations, Harvey instead proposed that:
The name of the membrane found between the capillary and the podocyte where filtration happens
Basement
What is this?
Basophil: type of white blood cell ( = leukocyte) with vesicles containing histamine.
Why are women given extra progesterone to establish a pregnancy for IVF?
Because the woman has not gone through a normal menstrual cycle extra progesterone is usually given as a tablet placed in the vagina, to ensure that the uterus lining is maintained.
When do the bile duct and the pancreatic duct meet?
Before they enter the small intestine.
Answers: What type of blood groups are on this chart?
Ben: Blood Group O Marissa: Blood Group A- Erik: Blood Group B+ Vanessa: Blood Group AB+
What protein does the basement membrane contain?
Can go out and recoil = Elastin (found in the basement membrane that surrounding the Alveoli) --> smokers damage the elastin = you can not expel air easily from the lungs = air doesn't easily go out = very small shallow breaths, but can't get out the old air.
Capillaries carry blood through tissues. They have permeable walls that allow exchange of materials between the cells of the tissue and the blood in the capillary.
Capillaries Diagram
they exchange materials between blood and tissue
Capillaries have walls that are only a single cell thick because
1. The capillary wall may be continuous with endothelial cells held together by tight junctions to limit permeability of large molecules 2. In tissues specialised for absorption (e.g. intestines, kidneys), the capillary wall may be fenestrated (contains pores) 3. Some capillaries are sinusoidal and have open spaces between cells and be permeable to large molcules and cells (e.g. in liver)
Capillaries structure may vary depending on its location in the body and specific role:
1) Both atria and ventricles filling with blood 2) Heart muscle (atria and ventricles) relaxing. Called diastole. 3) When atria are full and ventricles just 70% full SAN sends electrical impulse across walls of atria 4) Atrial systole — electrical impulse passes through atrial walls 5) Blood from atria pushed into ventricles to completely fill them 6) AVN delays impulse for short time period 7) Electrical impulse travels down a bundle of heart cells specialized for electrical conduction in the septum (Bundle of His) 8) Ventricular systole as electrical impulse passes from apex through the wall of ventricles (again through specialized cells, called Purkinje fibres) 9) Pressure increases in the ventricles 10) AV valves close — first (lub) sound of the heartbeat (atria will shortly start to refill again) 11) Semilunar valves open 12) Blood leaves the heart in the aorta and pulmonary artery 13) Then ventricular diastole 14) Semilunar valves close — second, dub sound of heart beat 15) AV valves open when pressure in the ventricles drops below that of the refilling atria 16) Both atria and ventricles filling with blood — see step 1 (repeat cardiac cycle).
Cardiac cycle — events occurring during one complete heart beat
What does it appear to do in the uterus?
Causes the thickening and increased vascularity of the endometrium
1: Pathogens with antigens on their surface invade the body. 2. Pathogen is ingested by a macrophage (a type of phagocyte) and an antigen from the pathogen is displayed/presented on the macrophage plasma membrane. 3: A cell called an inactive helper T cell is converted into an activated helper T cell by association with the antigen presenting macrophage. An inactive helper T cell binds to the antigen that is presented on the macrophage. Only an inactive helper T cell with antibody displayed on its plasma membrane that matches the antigen will be activated. Note T cells are so called because they mature in a part of the lymphatic system called the Thymus gland - this can be found in the neck region. 4. An inactive B cell (with an antibody in its plasma membrane that matches the antigen) binds the antigen. The activated helper T cell then binds to the inactive B cell (the one with the antigen bound to the antibody on its surface). The helper T cell sends a chemical message to activate the B cell 5: The activated B cell starts to divide by mitosis to produce a clone of cells called plasma cells and memory cells. This is called clonal selection. Plasma cells become large due to extra cytoplasmic volume and contain a very extensive rER. Large amounts of antibodies are secreted through vesicles via exocytosis. 6: Production of Memory Cells - Memory cells are T cells and B cells that also formed when the activated T cell and B cell divide by mitosis. After the antibodies have been made and disappeared the memory cells persist and allow a rapid (secondary) response if the pathogen is encountered again. Memory cells give long term immunity.
Cells that are recognized as non-self / foreign due to their unique surface antigens trigger an immune response as outlined:
Duct where many nephrons combine
Collecting Duct
1. Atherosclerosis can lead to blood clots which cause coronary heart disease when they occur in coronary arteries 2. Myocardial tissue requires the oxygen and nutrients transported via the coronary arteries in order to function 3. If a coronary artery becomes completely blocked, an acute myocardial infarction (heart attack) will result 4. Blockages of coronary arteries are typically treated by by-pass surgery or creating a stent (e.g. balloon angioplasty)
Consequences of Coronary Occlusion
What happens conversely to overeating?
Conversely, periods of starvation lead to a reduction in adipose tissue and hence less leptin is released, triggering hunger
fatty plaque building up in the inner lining of coronary arteries, which become occluded (narrowed).
Coronary artery disease is caused by
Digestive enzymes are secreted predominantly by
the pancreas, although other organs also contribute (salivary gland, stomach)
What are the two tubes called that enter each lung?
1) Esophagus (food) --> there is a little flap of tissue that closes over your windpipe when you swallow, because you can't breath and eat at the same time = you cough = reflex. 2) Trachea (breathing)
Respiratory system structure
- air enters through the nose or mouth and passes through the pharynx to the trachea - air travels down the trachea until it divides into 2 bronchi which connect to the lungs -right lung has 3 lobes, the left has 2 -inside each lung the bronchi the bronchi divide into many smaller airways called bronchioles, greatly increasing surface area -each bronchiole terminates with a cluster of air sacs called alveoli
The Respirator System
-Air enters the respiratory system through the nose or mouth and passes through the pharynx to the trachea -The air travels down the trachea until it divides into two bronchi (singular: bronchus) which connect to the lungs -The right lung is composed of three lobes, while the left lung is only comprised of two (smaller due to position of heart) -Inside each lung, the bronchi divide into many smaller airways called bronchioles, greatly increasing surface area -Each bronchiole terminates with a cluster of air sacs called alveoli, where gas exchange with the bloodstream occurs-
Systole 2
-As the ventricles contract, the ventricular pressure becomes greater than atrial pressure and the AV valves close to prevent back flow -with both sets of heart valves closed pressure builds in the contracting ventricles
Outline the IVF process:Outline the IVF process:
1. (IVF) is fertilization outside body / "in glass"; 2. drugs given to stop normal menstrual cycle; (This drug, often in the form of a nasal spray, stops the pituitary gland secreting FSH and LH, which in turn stops estrogen and progesterone production. Doctors can now control the timing and amount of egg production in the ovaries) 3. Inject FSH to stimulate ovaries/stimulate production of eggs; (These injections are intramuscular and given daily for about 10 days = more than needed. The hope is to get between 12 and 20 follicles. This is called superovulation = production of more than one egg that can be implanted) 4. hCG hormone given to mature the follicles/facilitate development of corpus luteum/increase progesterone levels (hCG makes it easier to remove the eggs from the follicles); 5. Eggs are removed from follicles/ovaries/mother;(This happens when the follicles are about 18mm in diameter. Eggs are removed using ultrasound to guide a micropipette through the vagina wall and out to the ovary) 6. Male provides sperm/sperm donor; 7. Washing / capacitation of sperm - this concentrates the sperm into a small volume (to be mixed with the eggs in the petri-dish); 8. Eggs are mixed with sperm;(Each egg is mixed with 50,000 to 100,000 sperm cells which is incubated at 37˚C overnight to encourage fertilisation = fertilized egg will start mitosis to become an embryo) 9. 2-3 embryos are implanted into uterus;(This is done when they are about 48 hours old. Additional progesterone may be given to keep uterine lining in place) 10. Pregnancy test is done to see if implantation/pregnancy has occurred (hCG is spewed out by the embryo to keep the lining of the uterus, which includes a lot of blood capillaries in the wall for gas exchange and respiration aka. the placenta builds aka. the baby's life support with blood transporting the nutrients, oxygen, etc.);
Describe the processes involved in absorbing different nutrients across the cell membrane of villus epithelium cells lining the small intestine.
1. (simple diffusion) of nutrients (eg. lipids) along/down a concentration gradient . 2. facilitated diffusion of nutrients (eg. fructose) involves movement through channel proteins . 3. active transport of nutrients (eg. (iron) ions/glucose/amino acids) against a concentration gradient / involving protein pumps. 4. endocytosis / by means of vesicles (eg. cholesterol in lipoprotein particles)
What are the advantages / disadvantages of being an osmoregulator?
1. A disadvantage of being an osmoregulator is that you need to expend energy to keep your internal solute concentrations within narrow limits. 2. You may need to use active transport (requires ATP) to intake or remove ions from cells (eg. you need to make ATP to produce proteins like aquaporins). 3. However, the advantage is that the internal environment in the cell is optimum for enzymatic function (cells do not plasmolyse = loose water = shrink OR ALSO = burst = too much water intake). 4. Osmoconformers are animals whose internal solute concentration tends to be the same as the osmolarity of the external environment. An example is a squid. Sharks are also osmoconformers. As are sea squirts.
Sex determination in males
1. A gene on the Y chromosome causes embryonic gonads to develop as testes and secrete testosterone. Gonads are sex organs Embryos develop identically for the first 8 weeks. At 8 weeks if the SRY gene (Sex Determining Region on the Y chromosome, shown as the smaller chromosome below) is present it codes for a DNA-binding protein called TDF (Testis Determining Factor). Testis determining factor acts as a "transcription factor". It increases the rate of transcription of genes involved in testis development. The testes develop testosterone secreting cells which continue to produce testosterone until about week 15. During this time, testosterone causes the male genitalia to develop. At puberty, testosterone is respnsible for sperm production and secondary sexual characteristics e.g deepening voice, facial hair etc For HL only review: It can bind to DNA at the promoter region in front of the coding regions of genes and cause the binding of RNA polymerase. This will increase the expression of genes that cause testis development by promoting mRNA transcription of these genes. TDF can influence transcription. It is called a transcription factor. You can watch an animation that shows how transcription factors influence transcription here (Links to an external site.).
Plasmolysis
1. A phenomenon in walled cells in which the cytoplasm shrivels and the plasma membrane pulls away from the cell wall; occurs when the cell loses water to a hypertonic environment. 2. Eg. Blood glucose too high
What generates the resting potential?
1. A sodium potassium pump in the plasma membrane generates the resting potential. 2. Three sodium ions are pumped out but only two potassium are pumped in 3. Negatively charge molecules (including proteins and acids) are found on the inside/cytoplasm and contribute to the negative charge inside the membrane 4. Additional information - not required -The membrane is more permeable to diffusion of potassium ions back out - 50 times more leak out than sodium diffuses in.
Egg
1. A typical egg cell is surrounded by two distinct layers - the zone pellucida (jelly coat) and corona radiata 2. The zona pellucida is a glycoprotein matrix which acts as a barrier to sperm entry (to prevent polyspermi) 3. The corona radiata is an external layer of follicular cells which provide support and nourishment to the egg cell 4. Within the egg cell are numerous cortical granules, which release their contents upon fertilisation to prevent polyspermy 5. Although diagrams of egg cells commonly include a haploid nucleus, no nucleus will form within the egg until after fertilisation has occurred (the egg cell is arrested in metaphase II until it becomes fertilised by a sperm)
Sperm
1. A typical human spermatozoa can be divided into three sections - head, mid-piece and tail 2. The head region contains three structures - a haploid nucleus, an acrosome cap and paired centrioles 3. The haploid nucleus contains the paternal DNA (this will combine with maternal DNA if fertilisation is successful) 4. The acrosome cap contains hydrolytic enzymes which help the sperm to penetrate the jelly coat of the egg 5. The centrioles are needed by a zygote in order to divide (egg cells expel their centrioles within their polar bodies) 6. The mid-piece contains high numbers of mitochondria which provide the energy (ATP) needed for the tail to move 7. The tail (flagellum) is composed of a microtubule structure called the axoneme, which bends to facilitate movement
3. Sliding Mechanism of Actin and Myosin
1. ATP binds to the myosin head, breaking the cross-bridge between actin and myosin 2. ATP hydrolysis causes the myosin heads to change position and swivel, moving them towards the next actin binding site 3. The myosin heads bind to the new actin sites and return to their original conformation 4. This reorientation drags the actin along the myosin in a sliding mechanism 5. The myosin heads move the actin filaments in a similar fashion to the way in which an oar propels a row boat
Basics you need to know about Internal Fertilisation:
1. Arrival - Sperm are first chemically attracted toward the egg. Many sperm will reach the egg. 2. Binding -When a sperm moves through the follicle cells and arrives at the zona pellucida (pellucid means clear - hence the term "lucid" in English) a sperm cell binds to a glycoprotein in the zona pellucida and this triggers the acrosome reaction. 3. Acrosome reaction - A large membrane bound sac of enzymes in the head of the sperm (the acrosome - from Greek "akros" meaning "at the top" and "some" meaning structure) releases hydrolytic enzymes which digest their way through the glycoproteins of the zona pellucida. The sperm can now move to the plasma membrane of the egg. 4. Fusion - During the acrosome reaction proteins that allow binding to the egg membrane become exposed. The plasma membrane of sperm and egg now fuse. The sperm nucleus enters the egg. This membrane fusion triggers the cortical reaction in the egg. 5. Cortical reaction - Thousands of small vesicles called cortical granules (cortical is derived from "cortex" which in Latin means the bark or outer layer) which are located just beneath the egg plasma membrane fuse with the membrane and release their contents by exocytosis. Enzymes from the cortical granules cause cross linking of glycoproteins in the zona pellucida making it hard, a preventing further sperm entry. It prevents polyspermy. 6. Mitosis - The two haploid nuclei undergo mitosis using the same centrioles and spindle fibres and the end result will be a two cell embryo with each cell having two copies of each chromosome.2nucleiundergomitosisusingsamemictrotubules/centrioles=2xdiploidcells.
The Malphigian system in insects carries out osmoregulation and removal of nitrogenous wastes:
1. Arthropods have a circulating fluid called hemolymph. 2. This liquid bathes the body cells. 3. The body cells take nutrients from it and deposit wastes into it. 4. A basic circulatory system keeps the liquid moving around the insects body. You are not expected to know about the insect circulatory system. 5. Nitrogenous waste in the form of uric acid needs to be removed from this liquid. This is excretion. 6. Water and solute balance also needs to be regulated. This is called osmoregulation. 7. Insects have tubes that branch off from their intestinal tract. 8. They are called Malphigian tubules. They are named after the Italian biologist Marcello Malpighi (b 1628, d 1694) and father of microscopic anatomy. 8. The Malphigian tubules are closely associated with the digestive system of the insect. The tubules are blind ending and branch extensively through the insects body.
Water Reabsorption
1. As the collecting duct passes through the medulla, the hypertonic conditions of the medulla will draw water out by osmosis 2. The amount of water released from the collecting ducts to be retained by the body is controlled by anti-diuretic hormone (ADH) 3. ADH is released from the posterior pituitary in response to dehydration (detected by osmoreceptors in the hypothalamus) 4. ADH increases the permeability of the collecting duct to water, by upregulating production of aquaporins (water channels) 5. This means less water remains in the filtrate, urine becomes concentrated and the individual urinates less (i.e. anti-diuresis) 6. When an individual is suitably hydrated, ADH levels decrease and less water is reabsorbed (resulting in more dilute urine)
Explain how an impulse passes along the membrane of a neuron
1. At resting potential membrane is polarized; 2. Interior is -70 mV/negative relative to outside; 3. More sodium ions outside than inside; 4. More potassium ions inside than outside, but lateral movement of sodium from a region in action potential to neighboring region in resting potential allows threshold potential to be met and opens sodium ion channels; 5. Sodium ion channels open; 6. Sodium ions rush to inside of cell; 7. Causing depolarization; (low sodium ions outside) 8. Sodium ion channels shut because change in polatrity; 9. Potassium ion channels open; 10. Potassium ions rush out; 11. Membrane becomes polarised again/repolarization; 12. Loss of too much potassium causes hyperpolarization; 13. Sodium-potassium pumps return membrane to resting polarity/potential; 14. Lateral movement of sodium from a region in action potential to neighboring region in resting potential allows threshold potential to be met and opens sodium ion channels; 15. Process repeated along the length of neuron (the axon) until it ends in a muscle (effector).
What was found out about leptin as a clinical function?
1. Because leptin suppresses appetite, it was considered as a form of treatment for individuals with clinical obesity 2. Theoretically, leptin injections would reduce hunger and limit food intake in obese individuals, leading to weight loss
Why does the CO2 need to be removed by the machine (by the sodalime)?
1. Because the CO2 increases acidity and denatures enzymes (proteins) 2. If you breath in air that is high in CO2 that will begin to drop the pH in your blood and signal the brain to send muscles to your muscles (eg. intercostals, diaphragm, abdomen) to speed up the rate at which you breath in and out, because you want to get rid of the extra CO2. 3. If you allowed extra CO2 in the air you breath in - it would artificially change the rate you breath in air, which is why you have to remove the CO2 from the air you breath out into the spirometer (because else you breath it in again).
Inhaling
1. Diaphragm muscles contract, causing the diaphragm to flatten and increase the volume of the thoracic cavity 2. External intercostals contract, pulling ribs upwards and outwards (expanding chest) 3. Additional muscle groups may help pull the ribs up and out (e.g. sternocleidomastoid and pectoralis minor)
What does this image show?
1. The image shows the decreased surface area and also an increased thickness of the alveolar walls. 2. The latter increases diffusion distance and so decreases the rate of gas exchange. 3. Decreased surface area also greatly decreases the area over which gas exchange can occur. Images on the right hand side are from emphysema patients.
Hormonal control of birth
1. Birth: During pregnancy progesterone inhibits secretion of oxytocin by the posterior pituitary and hence there are no contractions of the muscular uterine wall (the myometrium - "myo" for muscle, "metrium" is Latin for womb). 2. Towards the end of pregnancy progesterone levels begin to fall and oxytocin is secreted. This stimulates contraction of muscle fibres in the myometrium. 3. Oestrogen continues to rise before birth. Oestrogen levels overtake progesterone and high levels of estrogen increases the number of oxytocin receptors in the uterine muscle fibres. 4. Therefore increased estrogen means an increased response to oxytocin (positive feedback). The response is uterine contractions. They (uterine contractions) in turn stimulate the production of more oxytocin (positive feedback again) and so contractions in labour get progressively stronger. 5. While the uterine muscle contracts the muscle fibres in the cervix relax and becomes wider. The amniotic sac bursts, the amniotic fluid is released and after further uterine contractions the baby is pushed through the cervix and the vagina. Once the umbilical cord is broken the baby is physiologically independent. Contractions continue for some time until the placenta is expelled as the after birth. This is a video that charts the course of reproduction from sperm and egg through to birth. Be warned the birth is a bit gruesome.
Outline the glomerular filtration:
1. Blood plasma leaks through fenestrations in the capillary walls. 2. These fenestrations (Latin word for a "window" is "fenestra") are shown here. 3. High blood pressure and numerous large fenestrations allow for the leakage of a large volume of blood plasma (approx 20% in each flow through or about 180 litres per day). 4. Surrounding the capillary is a basement membrane providing support to the single layer of cells on either side (capillary endothelial cells and podocytes). 5. The basement membrane is made of glycoproteins and collagen and acts as a filter. 6. Material that has passed through the fenestrations and then the basement membrane finally passes through small gaps or filtration slits between the extensions of the podocyte cells. 7. Only small molecules can pass through the basement membrane and the filtration slits to enter the Bowman's capsule. 8. The basement membrane and the filtration slits both act as filters.
Explain the principles of synaptic transmission.....very commonly asked!!
1. Ca 2+ /calcium ions enter presynaptic neuron; 2. release of neurotransmitter/acetylcholine; from pre-synaptic membrane/neuron; 3. diffusion/movement across cleft/gap; 4. to post-synaptic membrane/neuron; 5. binding of the neurotransmitter to receptors/binding sites; 6. change in membrane permeability; 7. sodium ions flow into post-synaptic neuron; 8. depolarization of post-synaptic membrane; 9. initiation of an action potential; 10. removal of the neurotransmitter; 11. by enzyme / acetylcholinesterase; 12. inactivated neurotransmitter returns to pre-synaptic neuron;
The process of fertilization in humans involves a number of key processes, including:
1. Capacitation - biochemical changes which occur post ejaculation to improve sperm motility 2. Acrosome reaction - the release of hydrolytic enzymes which softens the zona pellucida (jelly coat) 3. Cortical reaction - hardening of the jelly coat post fertilization to prevent potential polyspermy
1. Capacitation
1. Capacitation occurs after ejaculation, when chemicals released by the uterus dissolve the sperm's cholesterol coat 2. This improves sperm motility (hyperactivity), meaning sperm is more likely to reach the egg (in the oviduct) 3. It also destabilises the acrosome cap, which is necessary for the acrosome reaction to occur upon egg and sperm contact
Synovial joints consist of three main components:
1. Cartilage - Lines the bone surface to facilitate smoother movement (reduce friction - where they could rub against each other), as well as absorbing shock and distributing load 2. Synovial fluid - Provides oxygen and nutrition to the cartilage, as well as lubrication (reduces friction) at the joint between the cartilage covered surfaces. 3. Joint capsule - Seals the joint space, provides stability by restricting the range of possible movements and holding in the synovial fluid.
Describe the process of blood clotting
1. Clotting (haemostasis) is a mechanism that prevents the loss of blood from broken vessels 2. Damaged cells and platelets release chemical signals called clotting factors which trigger a coagulation cascade: Clotting factors convert the inactive zymogen prothrombin into the activated enzyme thrombin. Thrombin catalyses the conversion of the soluble plasma protein fibrinogen into an insoluble form (fibrin). Fibrin forms an insoluble mesh of fibres that trap blood cells at the site of damage. 3. Clotting factors also cause platelets to become sticky, which then adhere to the damaged region to form a solid plug called a clot 4. The clot prevents further blood loss and blocks entry to foreign pathogens
Dehydration
1. Dehydration is a loss of water from the body such that body fluids become hypertonic 2. Individuals will experience thirst and excrete small quantities of heavily concentrated urine (to minimise water loss) 3. Blood pressure will drop (less water in plasma) and the heart rate will increase to compensate for this 4. The individual will become lethargic and experience an inability to lower body temperature (due to lack of sweat) 5. Severe cases of dehydration may cause seizures, brain damage and eventual death
While neurons may differ according to role (sensory, relay or motor), most share three basic components:
1. Dendrites - Short-branched fibres that convert chemical information from other neurons or receptor cells into electrical signals 2. Axon - An elongated fibre that transmits electrical signals to terminal regions for communication with other neurons or effectors 3. Soma - A cell body containing the nucleus and organelles, where essential metabolic processes occur to maintain cell survival
The process of muscular contraction occurs over a number of key steps, including:
1. Depolarisation and calcium ion release 2. Actin and myosin cross-bridge formation 3. Sliding mechanism of actin and myosin filaments 4. Sarcomere shortening (muscle contraction)
What do we use to suck air into our lungs?
1. Diaphragm (below your lungs & ribcage). 2. Lungs (sitting inside the thorax) 3. Heart (sitting inside the thorax)
How does thyroxine increase heat production from BAT?
1. Increased respiration in Brown Adipose Tissue (BAT) is responsible for rapid heat generation. 2. This heat energy would have otherwise been chemical energy stored in ATP as a result of aerobic respiration. 3. On the cristae of mitochondria found in BAT cells there are proteins, called uncoupling proteins (UCP). These proteins allow the flow of protons from an area of high concentration (in the inter-membrane space) back to the matrix. These protons would ordinarily pass through ATP synthase and the energy of the moving protons would be converted to stored energy in ATP. However, with uncoupling proteins the energy is released as heat. There is little generation of ATP as a result. 4. BAT is found in your body. Note that it is more prominent in babies, because babies have poorly developed thermoregulatory mechanisms e.g vasoconstriction and so need to be able to compensate for heat loss by rapid heat generation.
The release of histamine causes an inflammatory response that results in allergic symptoms:
1. Inflammation improves leukocytes mobility to infected regions by triggering vasodilation and increasing capillary permeability 2. Vasodilation is the widening (dilation) of blood vessels to improve the circulation of blood to targeted regions 3. Vasodilation causes redness (as vessel expansion moves blood closer to the skin) and heat (which is transported in blood) 4. Capillary permeability describes the capacity for leukocytes to leave the bloodstream and migrate into the body tissue 5. Increased permeability leads to swelling (more fluid leaks from the blood) and pain (swelling causes compression of nerves) 6. Redness, heat, swelling and localised pain are all typical symptoms of an allergic response
When blood glucose levels are high (e.g. after feeding):
1. Insulin is secreted from beta (β) cells of the pancreas and cause a decrease in blood glucose concentration 2. This may involve stimulating glycogen synthesis in the liver (glycogenesis), promoting glucose uptake by the liver and adipose tissue, or increasing the rate of glucose breakdown / absorption (by increasing cell respiration rates). These processes lower the blood glucose level.
Hemodialysis - Kidney dialysis involves the external filtering of blood in order to remove metabolic wastes in patients with kidney failure. Blood is removed and pumped through a dialyzer, which has two key functions that are common to biological membranes:
1. It contains a porous membrane that is semi-permeable (restricts passage of certain materials) 2. It introduces fresh dialysis fluid and removes wastes to maintain an appropriate concentration gradient 3. Kidney dialysis treatments typically last about 4 hours and occur 3 times a week - these treatments can be effective for years
Placenta - The placenta functions as the life support system for the foetus, serving two key functions:
1. It facilitates the exchange of materials between the mother and foetus 2. It secretes hormones to maintain the pregnancy after the corpus luteum has degenerated
Adaptations of small intestine for absorption:
1. It is 7m long = food spends many hours passing through. 2. Villi on the mucosa increase the surface area for absorption. 3. Epithelial cells have microvilli that increase the SA for absorption. 4. Epithelial cells have many mitochondria = aerobic respiration = ATP = Active transport & endocytosis also needs ATP.
Why is this elbow joint also a synovial joint?
1. It is called a synovial joint because it contains a liquid called synovial fluid. 2. Cells lining the inside of the joint capsule produces the synovial fluid. The word synovial comes from the Latin "synovia" which means "a thick fluid". The tricep insertion is found on the ulna. t comes before u in the alphabet.
The human elbow is capable of:
1. It is capable of angular movement in one direction (i.e. flexion and extension only) 2. A small amount of rotation may be possible, but excessive multiaxial movement will cause injury
Jet Lag
1. Jet lag is a physiological condition resulting from a change to the body's normal circadian rhythm 2. This alteration is caused by the body's inability to rapidly adjust to a new time zone following extended air travel ('jet' lag) 3. The pineal gland continues to secrete melatonin according to the old time zone so that the sleep schedule is not synchronised to the new timezone 4. Over the course of a few days, the retinal cells help the body adjust to the new timings. 5. Melatonin is sometimes used to reduce jet lag. It is taken orally at a time when sleep should ideally be commencing in the new time zone. 6. In trials, it has been shown to help when taken at sleep time, especially if flying east and crossing more than 5 time zones.
Focus on the advantages and disadvantages of these solutions. Treatments for kidney failure (2):
1. Kidney transplants 2. Greater independence of movement and travel 3. Recipients body can reject transplant (immune rejection = need to dampen the immune system but risk the chance of other diseases) but otherwise can be a long term solution (permanent) 4. Expensive 5. Major shortage of kidneys for transplant
Urinary Analysis
1. Kidneys prevent the excretion of blood cells and proteins (during ultrafiltration), as well as glucose (selective reabsorption) 2. Hence the presence of these materials in urine can be used as an indicator of disease 3. Glucose: The presence of glucose in urine is a common indicator of diabetes (high blood glucose = incomplete reabsorption) 4. Proteins: High quantities of protein in urine may indicate disease (e.g. PKU) or hormonal conditions (e.g. hCG = pregnancy) 5. Blood cells: The presence of blood in urine can indicate a variety of diseases, including certain infections and cancer 6. Drugs / toxins: Many drugs pass through the body into urine and can be detected (e.g. performance enhancing drugs)
Data Based Q's: Polio incidence in 2012 This figure provides data about polio incidence in the three countries where wild polio was endemic as of mid-2012. Suggest some of the challenges and epidemiologist might face in gathering reliable data (5)
1. Lack of access to populations in remote areas. 2. Lack of trust between affected individuals and epidemiologists 3. Lack of recognition of mild cases 4. mis-diagnosis 5. Language barriers 6. death before identification.
Modern Theory of Sexual Reproduction
1. Our current understanding of the mechanism of sexual reproduction is based on evidence discovered using light microscopes 2. Viable microscopes for such investigations were not invented until 17 years after the death of William Harvey 3. Based on available evidence, it is now known that a fetus forms from a combination of both male and females 'seeds' (gametes)
Mice Experiments
1. Leptin trials were initially conducted by surgically fusing the blood circulation of obese and healthy mice (parabiosis) 2. This experiment was conducted using mice that were either obese due to a leptin gene mutation (recessive gene ob that caused mice to be obese - 4 times the weight of normal mice. Mice with two copies of ob cannot produce leptin.) or a defective leptin receptor 3. When the obese mouse with no leptin was parabiotically fused to a healthy mouse: 4. Leptin in the blood of the healthy mouse was transferred to the obese mouse 5. The obese mouse responded to the leptin and began to lose weight, demonstrating the potential viability of leptin treatment 6. However, when the obese mouse with a defective leptin receptor was parabiotically fused to a healthy mouse: 7. Leptin was transferred to the healthy mouse (the obese mouse overproduced leptin to compensate for low receptor sensitivity) 8. The obese mouse remained obese as its body could not respond to leptin 9. The healthy mouse became emaciated (abnormal due to the abnormally high levels of leptin transferred into its bloodstream
Blood in the renal vein (i.e. after the kidney) will have:
1. Less urea (large amounts of urea is removed via the nephrons to form urine) 2. Less water and solutes / ions (amount removed will depend on the hydration status of the individual) 3. Less glucose and oxygen (not eliminated, but used by the kidney to generate energy and fuel metabolic reactions) 4. More carbon dioxide (produced by the kidneys as a by-product of metabolic reactions)
What a local current?
1. Local currents is the diffusion of sodium ions along the axon, both inside and outside the membrane. 2. It changes the voltage across the membrane from the resting potential -70mV to the threshold potential of -50mV. This causes an action potential, because voltage-gated sodium channels open.
causes of emphysema
1. Long term exposure to air borne irritants e.g tobacco smoke, coal and silica dust. 2. Damage to lung tissue leads to the increased movement of phagocytes to the area. 3. The phagocytes release proteases enzymes as part of their defensive function against pathogens. These protease enzymes can digest protein. 4. Elastin (protein) fibres are proteins found in the alveolar wall that help with lung elasticity (expansion and recoil). Protease enzymes from phagocytes can digest elastin and so the lung elasticity and alveolar architecture is damaged. 5. Our body cells normally produce a protease/enzyme inhibitor (A1AT - called alpha 1 anti trypsin) that prevents lung tissue damage by blocking the activity of the protease enzyme. This keeps the elastin protein involved in lung elasticity intact. 6. Smokers tend to produce less protease inhibitor (A1AT) and what they do produce is less effective because components of the tobacco smoke affect its activity. (This may also have a genetic basis (mutations in the gene for A1AT) and so small numbers of non smokers can develop emphysema) 7. 30% of smokers have protein degradation in alveoli walls which weaken and loose their intricate architecture. The removal of elastic protein fibres make it difficult for the lungs to recoil and so it becomes increasingly difficult to exhale. 8. The volume of air remaining in the lungs of a person with emphysema after they have exhaled will be higher than that of a person with normal lung function. This is due to a loss in lung elasticity (+ maybe you can also talk about lack of gas exchange)! 9. As a result, people with emphysema tend to have shallow breathing (short breaths) as the available volume in their lungs for new inhaled air is low.
There are two types of lipoproteins:
1. Low Density Proteins, LDL. (There is some scientific evidence that suggests that people who process triglycerides and produce too much LDL have increased risk of CHD.) 2. High Density Lipoproteins, HDL
Sequence of events in the menstrual cycle - note the positive and negative feedback involved. [common 8 Marks]
1. Low levels of progesterone (and estrogen) allow for menstruation - lining of the womb is shed (days1-5) 2. Low levels of estrogen and progesterone remove the negative feedback on FSH. 3. FSH levels begin to rise 4. This stimulates follicle development in the ovary 5. Increasing FSH levels stimulate estrogen production from follicle cells. 6. Estrogen in turn causes follicle cells to develop more FSH receptors on their plasma membrane andso respond more strongly to FSH which in turn stimulates more estrogen production. This is anexample of positive feedback. 7. Estrogen repairs the lining of the endometrium (during the follicular phase/control via the follicle). 8. Rising estrogen levels stimulate the production of LH (positive feedback) 9. LH brings about ovulation and development of corpus luteum. 10. Increasing LH inhibits estrogen and stimulates progesterone production from the corpus luteum 11. Progesterone continues to thicken and maintain the endometrium (during the luteal phase) 12. High progesterone inhibits the production of FSH (negative feedback) 13. If no fertilized egg arrives in the uterus, corpus luteum degenerates and progesterone levels fall 14. Lining of womb is shed - period again and negative feedback of FSH removed. Back to point 3. 15. If egg is fertilized corpus luteum continues to secrete progesterone and lining of the womb is not shed.
Terrestrial animals have less access to water and hence must package nitrogenous waste in less toxic forms:
1. Mammals eliminate their nitrogenous wastes as urea, which is less toxic and hence can be stored at higher concentrations 2. Reptiles and birds eliminate wastes as uric acid, which requires more energy to make but is relatively non-toxic and requires even less water to flush (it is eliminated as a semi-solid paste)
How do cells in the liver remove excess glucose?
1. The cells in the liver (hepatocytes) remove excess glucose and convert it to glycogen (storage carbohydrate in animals). 2. This is an anabolic reaction This is under the direction of the protein hormone, insulin, from the endocrine glands in the pancreas. 3. If glucose levels are too low in the blood plasma a protein hormone called glucagon is released form endocrine cells in the pancreas and convert glycogen back to glucose (a hydrolysis/catabolic reaction).
Loop of Henle and DCT (process)
1. Na+ are pumped out of the ascending limb and so the tissue fluid surrounding the medulla cells increases its sodium concentration/become more concentration/osmolarity increases. Remember, the ascending limb is impermeable to water. 2. Water flowing down the descending limb can now move from a dilute/hypotonic solution inside the loop of Henle (in the filtrate) to a concentration solution outside, in the tissue fluid. The descending limb does not pump out sodium ions. 3. As the fluid in the descending (down) limb loses water it becomes more concentrated (the more Na+ and water you can pump out = the more concentrated the urine becomes = the larger the medulla). As it turns the bend at the bottom of the loop there is now an abundance of sodium (in the concentrated filtrate) for the active transport pumps and so they can continue to remove large amounts into the fluid between the medulla cells. 4. The system allows you have a gradient that enables you to continue to draw water from the descending limb. The most concentrated region of the medulla will be in the vicinity of the most concentrated filtrate in the loop and so allow continued osmosis (the water leaves by osmosis and enters the surrounding capillaries). The least concentrated region will be where the contents of the loop are least concentrated/most dilute and so you can draw water from here also. 5. The water is taken up by unbranched capillaries that run parallel the Loop of Henle called the vasa recta ("vasa" means "vessel" and "recta" means "straight") ECF - extracellular fluid, the same as tissue fluid, the liquid surrounding the cells.Do not worry about the term counter current multiplier.
Excretion of nitrogenous waste (across the animal kingdom):
1. Nitrogenous bases from proteins (amino acids) 2. DNA / RNA / nucleic acids = nucleotides also gets rid of amino group (NH2).
While the processes of spermatogenesis and oogenesis follow the same basic pathway, several key differences exist:
1. Number of cells produced a) In spermatogenesis, the cells divide equally during meiosis to produce four functional gametes b) In oogenesis, the cells do not divide equally and as a result only one functional gamete is formed (plus 2 - 3 polar bodies) 2. Size of cells produced a) In spermatogenesis, the cells that are formed following differentiation are all of equal size with equal amounts of cytoplasm b) In oogenesis, one daughter cell (the ovum) retains all of the cytoplasm, while the other daughter cells form polar bodies c) The polar bodies remain trapped within the surrounding layer of follicle cells until they eventually degenerate 3. Timing of the process a) In spermatogenesis, the production of gametes is a continuous process that begins at puberty and continues until death b) In oogenesis, the production of gametes is a staggered and finite process: c) It begins before birth (prenatally) with the formation of a fixed number of primary oocytes (~40,000) d) It continues with the onset of puberty according to a monthly menstrual cycle e) It ends when hormonal changes prevent the further continuance of the menstrual cycle (menopause)
Alimentary Canal:
1. Oesophagus • A hollow tube connecting the oral cavity to the stomach (separated from the trachea by the epiglottis) • Food is mixed with saliva and then is moved in a bolus via the action of peristalsis 2. Stomach • A temporary storage tank where food is mixed by churning and protein digestion begins • It is lined by gastric pits that release digestive juices, which create an acidic environment (pH ~2) 3. Small Intestine • A long, highly folded tube where usable food substances (nutrients) are absorbed • Consists of three sections - the duodenum, jejunum and ileum 4. Large Intestine • The final section of the alimentary canal, where water and dissolved minerals (i.e. ions) are absorbed • Consists of the ascending / transverse / descending / sigmoidal colon, as well as the rectum
Historical Perspective of Sexual Reproduction
1. One of the earliest theories as to how animals reproduce sexually was the 'soil and seed' theory proposed by Aristotle 2. According to this theory, the male produces a 'seed' which forms an 'egg' when mixed with menstrual blood (the 'soil') 3. The 'egg' then develops into a fetus inside the mother according to the information contained within the male 'seed' alone
Oogenesis
1. Oogenesis describes the production of female gametes (ova) within the ovaries (and, to a lesser extent, the oviduct) 2. The process begins during foetal development, when a large number of primordial cells are formed by mitosis (~40,000) 3. These cells (oogonia) undergo cell growth until they are large enough to undergo meiosis (becoming primary oocytes) 4. The primary oocytes begin meiosis but are arrested in prophase I when granulosa cells surround them to form follicles 5. The primary oocytes remain arrested in prophase I until puberty, when a girl begins her menstrual cycle 6. Each month, hormones (FSH) will trigger the continued division of some of the primary oocytes 7. These cells will complete the first meiotic division to form two cells of unequal size 8. One cell retains the entirety of the cytoplasm to form a secondary oocyte, while the other cell forms a polar body 9. The polar body remains trapped within the follicle until it eventually degenerates 10. The secondary oocyte begins the second meiotic division but is arrested in metaphase II 11. The secondary oocyte is released from the ovary (ovulation) and enters into the oviduct (or fallopian tube) 12. The follicular cells surrounding the oocyte form a corona radiata and function to nourish the secondary oocyte 13. If the oocyte is fertilised by a sperm, chemical changes will trigger the completion of meiosis II and the formation of another polar body (the first polar body may also undergo a second division to form a third polar body) 14. Once meiosis II is complete the mature egg forms a ovum, before fusing its nucleus with the sperm nucleus to form a zygote
Cross-Sections of Reproductive Tissue: Oogenesis
1. Oogenesis in the ovaries is not a continuous process and proceeds according to a monthly menstrual cycle 2. Consequently, certain developing follicles will only be visible at particular stages in the cycle 3. As a follicle matures it will grow larger in size, allowing for comparisons to be made between primary and secondary follicles 4. Unlike in spermatogenesis, the outer germline epithelium of the ovaries does not directly contribute to gamete formation
Responses to changes in osmolarity of the environment:
1. Osmolarity refers to the solute concentration of a solution. 2. Many organisms can maintain their internal solute concentration (osmolarity) within a narrow range even when external solute concentrations (osmolarities) change. They are called osmoregulators. 3. All terrestrial animals e.g humans, freshwater animals e.g freshwater fish, and some saltwater organisms (like bony fish) are osmoregulators.
Membrane Transport Mechanisms
1. Secondary Active Transport: A transport protein couples the active translocation of one molecule to the passive movement of another (co-transport). Eg. Glucose and amino acids are co-transported across the epithelial membrane by the active translocation of sodium ions (Na+). 2. Facilitated Diffusion: Channel proteins help hydrophilic food molecules pass through the hydrophobic portion of the plasma membrane, as they are often situated near specific membrane-bound enzymes (creates a localised concentration gradient). Eg. Certain monosaccharides (e.g. fructose), vitamins and some minerals are transported by facilitated diffusion. 3. Osmosis: Water molecules will diffuse across the membrane in response to the movement of ions and hydrophilic monomers (solutes). The absorption of water and dissolved ions occurs in both the small and large intestine. 4. Simple Diffusion: Hydrophobic materials (e.g. lipids) may freely pass through the hydrophobic portion of the plasma membrane and once absorbed, lipids will often pass first into the lacteals rather than being transported via the blood.
Different methods of membrane transport are used in epithelium cells to absorb different nutrients:
1. Simple diffusion, in which nutrients pass down the concentration gradient between phospholipids in the membrane. (Eg. hydrophobic nutrients such as fatty acids and monoglycerides.) 2. Facilitated diffusion, in which nutrients pass down the concentration gradient through specific channel proteins in the membrane. (Eg. hydrophilic nutrients such as fructose.) 3. Active transport, in which nutrients are pumped through the membrane against the concentration gradient by specific pump proteins. (Eg. mineral ions such as sodium, calcium and iron.) 4. Endocytosis (pinocytosis), in which small droplets of the fluid are passed through the membrane by means of vesicles. (Eg. triglycerides and cholesterol in lipoprotein particles).
Causes of lung cancer:
1. Smoking (87%). (Tobacco smoke has a number of mutagenic chemicals e.g nitrosamine.) 2. Passive smoking (3%) 3. Air pollution (5%). (Mostly exhaust fumes from vehicles containing harmful chemicals like nitrogen oxides. Smoke from burning wood, rubbish, coal etc.) 4. Radon gas (is a radioactive gas released from rocks like limestone. Houses build in limestone rich areas that are poorly ventilated will have high radon levels which will be inhaled and can result in increased incidence of lung cancer (approx 1000 death per year in the UK are linked to Radon)). 5. Asbestos and silica from industrial process can cause lung cancer. Estimates that 4% of cancers are due to these chemicals. Here is a link to asbestosis (Links to an external site.) (which increases the risk of developing lung cancer). Note asbestosis is not on the syllabus.
What are the disadvantages and advantages. of uric acid for terrestrial animals?
1. Some terrestrial animals convert ammonia to uric acid. 2. This requires considerable expenditure of energy but the advantages are that uric acid can crystallise out and so does not require water. 3. This reduces weight in flying birds and insects. 4. Also uric acid in bird eggs is not soluble and so does not build up to toxic concentrations within the egg. 5. As a result no harm comes to the developing embryo. 6. This is an evolutionary adaptation to reproduction using eggs. 7. Insects also excrete uric acid.
Spermatogenesis
1. Spermatogenesis describes the producton of spermatozoa (sperm) in the seminiferous tubules of the testes 2. The process begins at puberty when the germline epithelium of the seminiferous tubules divides by mitosis 3. These cells (spermatogonia) then undergo a period of cell growth, becoming spermatocytes 4. The spermatocytes undergo two meiotic divisions to form four haploid daughter cells (spermatids) 5. The spermatids then undertake a process of differentiation in order to become functional sperm cells (spermatozoa)
Cross-Sections of Reproductive Tissue: Spermatogenesis
1. Spermatogenesis in the seminiferous tubules starts at the outer lining of the tubule (germline epithelium) 2. As the germ cells divide by meiosis they move towards the inner lining before being released into the lumen as sperm 3. Non-dividing cells within the tubule lining will represent the Sertoli cells, which nourish and support the spermatocytes 4. Cells located externally to the tubule will likely represent interstitial cells (Leydig cells), which produce testosterone
The pancreas is an example of an exocrine gland as it secretes enzymes, through a duct, into the lumen of the small intestine. Here they carry out a number of hydrolysis reactions:
1. Starch to maltose by pancreatic amylase. 2. Triglycerides to fatty acids and glycerol by pancreatic lipase. 3. Phospholipids to fatty acids, glycerol and phosphate by pancreatic phospholipase. 4. Proteins and polypeptides are digested to shorter peptides by protease enzymes called pancreatic endopeptidases.
In Vitro Fertilisation - Superovulation
1. Superovulation involves using artificial doses of hormones to develop and collect multiple eggs from the woman 2. The patient is firstly injected with large amounts of FSH to stimulate the development of many follicles 3. The follicles are then treated with human chorionic gonadotrophin (hCG) - a hormone usually produced by a developing embryo 4. hCG stimulates the follicles to mature and the egg is then collected (via aspiration with a needle) prior to the follicles rupturing
As a result of these sleep disturbances, individuals suffering from jet lag will often experience symptoms associated with fatigue:
1. Symptoms of jet lag include headaches, lethargy, increased irritability and reduced cognitive function 2. Jet lag should only last a few days and symptoms should resolve as the body resynchronises its circadian rhythm
Synaptic transmission
1. Synapses are junctions between neurons or between neurons and muscle cells or secretory cells in glands (effectors) or between receptor cells and nerve cells. 2. Chemicals called neurotransmitters are used to send signals across synapses. 3. A neurotransmitter crosses a fluid filled gap called a synaptic cleft which separates the pre synaptic neuron from the post synaptic one. 4. A sequence of events results in the signal being sent across the cleft.
Structures of the Male Reproductive System The following structures all contribute to the production of sperm and semen as part of the reproductive process in males Structures are organised according to the path taken by sperm (from production to release)
1. Testis - The testis (plural: testes) is responsible for the production of sperm and testosterone (male sex hormone) 2. Epididymis - Site where sperm matures and develops the ability to be motile (i.e. 'swim') - mature sperm is stored here until ejaculation 3. Vas Deferens - Long tube which conducts sperm from the testes to the prostate gland (which connects to the urethra) during ejaculation 4. Seminal Vesicle - Secretes fluid containing fructose (to nourish sperm), mucus (to protect sperm) and prostaglandin (triggers uterine contractions) 5. Prostate Gland - Secretes an alkaline fluid to neutralise vaginal acids (necessary to maintain sperm viability) 6. Urethra - Conducts sperm / semen from the prostate gland to the outside of the body via the penis (also used to convey urine)
Testosterone
1. Testosterone is produced by developing testes in the fetus. 2. It causes pre-natal development of male genitalia, including the penis, sperm duct and prostate gland. 3. During puberty testosterone production increases. 4. It stimulates development of male secondary sexual characteristics during puberty, including growth of the testes, penis and pubic hair. 5. Testosterone also stimulates sperm production from puberty onwards.
Debunking the 'Soil and Seed' Theory
1. The 'soil and seed' theory was a popular doctrine for hundreds of years before it was eventually debunked by William Harvey 2. William Harvey studied the sexual organs of female deer after mating in an effort to identify the developing embryo 3. He was unable to detect a growing embryo until approximately 6 - 7 weeks after mating had occurred 4. He concluded that Aristotle's theory was incorrect and that menstrual blood did not contribute to the development of a fetus 5. Harvey was unable to identify the correct mechanism of sexual reproduction and incorrectly asserted that the fetus did not develop from a mixture of male and female 'seeds'
The antigens on red blood cells:
1. The ABO blood groups system is based on the presence or absence of a group of glycoproteins in the membranes of red blood cells. 2. Glycoproteins in this group cause antibody production if a person does not naturally possess them, so they are known as antigens. 3. 0, A and B antigens are three different versions of the glycoprotein. 4. The 0 antigen is always present. The A antigen is made by adding an N-acetyllalactosamine molecule to the 0 antigen, and the B antigen is made by adding galactose.
What systems in our body are needed to remove CO2?
1. The Breathing System (to remove CO2) 2. The Circulatory System (transport CO2 from cells to lungs)
Spermatogenesis
1. The Greek word "sperma" means "seed". Spermatogenesis is the "creation of sperm". 2. It takes place within the seminiferous tubules found in the testis. 3. Each testis has up to 300m of coiled seminiferous tubules allowing you to produce about 1,500 sperm cells per second!! 4. Spermatogenesis (and Oogenesis) both involve the following steps: mitosis followed by cell growth, two divisions of meiosis (meiosis 1 and 2) and then final differentiation of the cells.
What does the Y chromosome include?
1. The Y chromosome includes a gene called the SRY gene (Sex Determining Region Y), which leads to male development 2. The SRY gene codes for a testis-determining factor (TDF) that causes embryonic gonads to form into testes (male gonads) 3. In the absence of the TDF protein (i.e. no Y chromosome), the embryonic gonads will develop into ovaries (female gonads)
How does immunity depend on the persistance of memory cells?
1. The adaptive immune system relies on the clonal expansion of plasma cells to produce sufficiently large numbers of antibodies 2. This means there is a delay between the initial exposure to a pathogen and the production of large quantities of antibodies 3. If pathogens can reproduce rapidly during this delay period, they can impede normal body functioning and cause disease 4. Memory cells are produced to prevent this delay in subsequent exposures and hence prevent disease symptoms developing 5. When a B lymphocyte is activated and divides to form plasma cells, a small proportion will differentiate into memory cells 6. Memory cells are long living and will survive in the body for many years, producing low levels of circulating antibodies 7. If a second infection with the same pathogen occurs, memory cells will react more vigorously to produce antibodies faster 8. As antibodies are produced faster, the pathogen cannot reproduce in sufficient amounts to cause disease symptoms 9. Hence, because pathogen exposure no longer causes the disease to occur, the individual is said to be immune
There are two major groups of organs which comprise the human digestive system:
1. The alimentary canal consists of organs through which food actually passes (oesophagus, stomach, small & large intestine) 2. The accessory organs aid in digestion but do not actually transfer food (salivary glands, pancreas, liver, gall bladder)
Basement Membrane - Ultrafiltration
1. The basement membrane is a fine mesh that restricts the passage of blood cells and proteins - it is the sole filtration barrier 2. Blood can exit the glomerulus directly through pores as the capillaries are fenestrated 3. The filtrate can enter the Bowman's capsule directly because the podocytes that surround the glomerulus contain filtration slits between their pedicels 4. The basement membrane lies between the glomerulus and Bowman's capsule
Consequences of Emphysema: What does this image show?
1. The image shows the decreased surface area and also an increased thickness of the alveolar walls. 2. The latter increases diffusion distance and so decreases the rate of gas exchange. 3. Decreased surface area also greatly decreases the area over which gas exchange can occur. Images on the right hand side are from emphysema patients.
Hormonal Control
1. The chemical regulators of the birthing process include oxytocin, oestrogen, progesterone and prostaglandin 2. After 9 months, the baby is fully grown and stretches the walls of the uterus - placing a strain on both mother and infant 3. This stress induces the release of chemicals which trigger a rise in the levels of estrogen (estriol in particular) 4. Estriol prepares the smooth muscle of the uterus for hormonal stimulation by increasing its sensitivity to oxytocin 5. Estriol also inhibits progesterone, which was preventing uterine contractions from occurring while the foetus developed 6. Now that the uterus is primed for childbirth, the brain triggers the release of oxytocin from the posterior pituitary gland 7. Oxytocin stimulates the uterine muscles to contract, initiating the birthing process (it also inhibits progesterone secretion) 8. The foetus responds to this uterine contraction by releasing prostaglandins, which triggers further uterine contractions 9. As the uterine contractions trigger the release of chemicals that cause further contractions, a positive feedback loop ensues 10. Contractions will stop when labour is complete and the baby is birthed (no more stretching of the uterine wall)
Material Exchange
1. The chorionic villi extend into the intervillous space (lacuna) and exchange materials between the mother and foetus 2. Chorionic villi are lined by microvilli to increase the available surface area for material exchange 3. Foetal capillaries within the chorionic villi lie close to the surface to minimise diffusion distance from blood in the lacunae 4. Materials such as oxygen, nutrients, vitamins, antibodies and water will diffuse from the lacunae into foetal capillaries 5. Foetal waste (such as carbon dioxide, urea and hormones) will diffuse from the lacunae into the maternal blood vessels
Mechanism of muscle contraction:
1. The contraction of skeletal muscle is achieved by the sliding of actin and myosin filaments. 2. For this to happen binding sites on actin for myosin must first be made available/exposed. 3. Then the myosin heads need to swivel/move. This is brought about by the using ATP. And so overall, ATP hydrolysis and the ability to form cross bridges between the filaments allow for muscle movement. 4. To expose binding sites on actin for myosin heads, calcium ions and the proteins troponin and tropomyosin are involved. The term "tropo" is from the greek verb "tropos" meaning "to change". It is used in English as a prefix to indicate change e.g. tropomyosin - changing myosin, troponin - a chemical that can change.
The contraction of the skeletal muscle is achieved by:
1. The contraction of the skeletal muscle is achieved by the sliding of actin and myosin filaments over eachother. 2. This pulls the ends of the sarcomeres together, making the muscle shorter. 3. The sliding of the filaments is an active process and requires the use of energy from ATP. 4. The hydrolysis of one molecule of ATP provides enough energy for a myosin filament to slide a small distance along an actin filament. 5. A repeated cycle of events is used to contract muscle sufficiently to move part of an animal body in the desired way.
3. Cortical Reaction
1. The cortical reaction occurs once a sperm has successfully penetrated an egg in order to prevent polyspermy 2. Cortical granules within the egg's cytoplasm release enzymes (via exocytosis) into the zona pellucida (jelly coat) 3. These enzymes destroy sperm binding sites and also thicken and harden the glycoprotein matrix of the jelly coat 4. This prevents other sperm from being able to penetrate the egg (polyspermy), ensuring the zygote formed is diploid
What are the advantages / disadvantages of being a osmoconformer?
1. The disadvantage of being an osmoconformer is that the internal osmolarity may not always be ideal for optimum body functions e.g enzymatic reactions within cells. 2. However, no energy is expended in maintaining the solute concentration of the cell/internal environment within narrow limits. 3. May die as their environment changes due to the bursting or shrinking of cells due to the environment their in. Internal solute concentration may become unsustainable for cells. 4. But a positive is that they do not need ATP.
In Vitro Fertilisation - Fertilisation
1. The extracted eggs are then incubated in the presence of a sperm sample from the male donor 2. The eggs are then analysed under a microscope for successful fertilisation
Implantation of Blastocyst
1. The final stage of early embryo development is the implantation of the blastocyst into the endometrial lining of the uterus 2. The blastocyst breaches the jelly coat that was surrounding it and preventing its attachment to the endometrium 3. Digestive enzymes are released which degrade the endometrial lining, while autocrine hormones released from the blastocyst trigger its implantation into the uterine wall 4. Only once the blastocyst is embedded within the uterine wall can the next stage of embryogenesis occur 5. The growing embryo will gain oxygen and nutrients from the endometrial tissue fluid, ensuring its continued development 6. The entire process (from fertilization to implantation) takes roughly 6 - 8 days
Establishing a Salt Gradient
1. The function of the loop of Henle is to create a high solute (hypertonic) concentration in the tissue fluid of the medulla 2. The descending limb of the loop of Henle is permeable to water but not salts 3. The ascending limb of the loop of Henle is permeable to salts but not water 4. This means that as the loop descends into the medulla, the interstitial fluid becomes more salty and hypertonic 5. Additionally, the vasa recta blood network that surrounds the loop of Henle flows in the opposite direction (counter-current) 6. This means that salts released from the ascending limb are drawn down into the medulla, further establishing a salt gradient
Explain the roles of the loop of Henle, medulla, collecting duct and ADH (vasopressin) in maintaining the water balance of the blood - Creating a Salt Gradient in the Medulla
1. The function of the loop of Henle is to create a salt bath concentration in the fluid surrounding the tubule 2. The descending limb of the loop of Henle is permeable to water, but impermeable to salts (Na+) 3. The ascending limb of the loop of Henle is permeable to salts (Na+), but impermeable to water 4. This means that as the loop descends into the medulla, the interstitial fluid becomes more salty (and less salty as it ascends into the cortex) 5. As the vasa recta blood network that surrounds the loop flows in the opposite direction (counter-current exchange), this further multiplies the effect
Hydrostatic Pressure
1. The glomerulus increases blood pressure by forming narrow branches (which also increases surface area for filtration) 2. This pressure is maintained by a narrow efferent arteriole (relative to the afferent arteriole), which restricts the outflow of blood, keeping pressure high 3. The net pressure gradient in the glomerulus forces blood into the capsule space
What is the mechanism of reabsorption?
1. The mechanism of reabsorption is by both active and passive means. (It bears similarities to glucose absorption across cells of epithelial cells on the surface of the villi). Follow the numbered steps. 2. Sodium ions pumped out using a sodium potassium pump. This is active transport and requires energy/ATP. It can move sodium and potassium against their concentration gradients. 3. Sodium ions diffuse into the cell down their concentration gradients by facilitated diffusion through a channel/carrier protein in the membrane. It does not require ATP. Glucose (and amino acids) can also pass through the channel protein and so it can be called sodium glucose co-transport using a sodium glucose co-transporter protein. 4. High levels of glucose and amino acids now found in the cell can move by diffusion (facilitated) out into the tissue fluid next to the capillary and on into the blood capillaries. The blood being replaced by new blood will allow for the concentration gradient to be maintained.
What is the menstrual cycle?
1. The menstrual cycle describes recurring changes that occur within the female reproductive system to make pregnancy possible 2. Each menstrual cycle lasts roughly one month (~28 days) and begins at puberty (menarche) before ending with menopause 3. Between puberty and the menopause, women who are not pregnant follow a cycle called the menstrual cycle. 4. This cycle is controlled by hormones FSH and LH, produced by the pituitary gland, and estrogen and progesterone, produced by the ovary. 5. Both positive and negative feedback control is used in the menstrual cycle. 6. During each menstrual cycle an oocyte (egg) matures inside a fluid-filled sac in the ovary called a follicle. T 7. he egg is released when the follicle bursts open during ovulation.
How do babies obtain nutrients to live in the womb?
1. The mother's placenta helps the baby "breathe" while it is growing in the womb. 2. Oxygen and carbon dioxide flow through the blood in the placenta. 3. Most of it goes to the heart and flows through the baby's body. At birth, the baby's lungs are filled with fluid.
The Role of the Pancreas
1. The pancreas secrete hormones e.g insulin, into the bloodstream (endocrine function). 2. It also secretes enzymes e.g pancreatic lipase, into the digestive tract (exocrine function). 3. The pancreas can respond to changes in blood sugar levels. 4. The set point is approx. 100mg/l, and the level is maintained in a narrow range around this point by a process called homeostasis. 5. The pancreas is both an exocrine and endocrine organ. 6. The endocrine cells are found in small "islands" of cells called Islets of Langerhans.
Role of ADH in the collecting duct including overall summary of kidney functions:
1. The peptide hormone ADH released from the posterior pituitary causes membrane protein allowing water movement (called aquaporins) to embed in the membrane and hence increases water reabsorption from the collecting duct 2. If the solute concentration of the blood is too low/hypotonic (the blood is dilute), little ADH is produced and little water is reabsorbed. Hence a large volume of dilute urine is produced. 3. If blood solute concentration is too high/hypertonic, chemoreceptors in hypothalamus detect the change and ADH is produced from neurosecretory cells in posterior pituitary. 4. This causes the walls of the collecting duct (and distal convoluted tubule) to become more permeable and water is drawn from the filtrate into the more concentrated medulla region and from there into the blood capillaries. 5. The action of the kidney helps keep the relative amounts of water and solutes in the blood in balance. This is called OSMOREGULATION.
Structure of the Placenta
1. The placenta is a disc-shaped structure that nourishes the developing foetus 2. It is formed from the development of the trophoblast upon implantation and eventually invades the uterine wall 3. Maternal blood pools via open ended arterioles into intervillous spaces within the placenta called lacunae 4. Chorionic villi extend into these pools of blood and mediate the exchange of materials between the foetus and the mother 5. Exchanged material is transported from the villi to the foetus via an umbilical cord, which connects the foetus to the placenta 6. Upon birth, the placenta is expelled from the uterus with the infant - it is then separated from the infant by severing the umbilical cord (the point of separation becomes the belly button)
Hormonal Role
1. The placenta takes over the hormonal role of the ovaries (at ~12 weeks) and begins producing estrogen and progesterone 2. Estrogen stimulates the growth of uterine muscles (myometrium) and the development of the mammary glands 3. Progesterone maintains the endometrium, as well as reducing uterine contractions and potential maternal immune responses 4. Both estrogen and progesterone levels drop near the time of birth
Explain the reabsorption of glucose, water and salts in the proximal convoluted tubule, including the roles of microvilli, osmosis and active transport - Selective Reabsorption in the Proximal Convoluted Tubule
1. The proximal convoluted tubule extends from the Bowman's capsule and is where most selective reabsorption in the nephron occurs 2. All glucose, amino acids, vitamins and hormones are reabsorbed here, along with most (~80%) of the mineral ions and water 3. The proximal convoluted tubule has a microvilli cell lining to increase the surface area for the absorption of materials from the filtrate 4. There are also a large number of mitochondria in these cells, as reabsorption from the filtrate involves active transport 5. Once materials have been activly reabsorbed into the tubule cells, they can passively diffuse into the bloodstream (along the concentration gradient) 6. Mineral ions and vitamins are actively transported via protein pumps or carrier proteins 7. Glucose is actively transported across the membrane in symport with sodium 8. Water follows the movement of the ions passively (via osmosis)
This is a blood capillary, which has branched from another blood vessel, which blood vessel is it?
1. The pulmonary artery, because it left the heart carrying blood without oxygen, and broke into hundreds of capillaries forming around the lungs. 2. This capillary will then want to go to the heart via the Pulmonary vein (because it's becoming oxygenated) and enter the heart through the left atrium.
The epithelial lining of villi contains several structural features which optimise its capacity to absorb digested materials:
1. Tight Junctions: Occluding associations between the plasma membrane of two adjacent cells, creating an impermeable barrier, which keep digestive fluids separated from tissues and maintain a concentration gradient by ensuring one-way movement 2. Microvilli borders significantly increase surface area of the plasma membrane (>100×), allowing for more absorption to occur, also the membrane will be embedded with immobilised digestive enzymes and channel proteins to assist in material uptake 3. Mitochondria - epithelial cells of intestinal villi will possess large numbers of mitochondria to provide ATP for active transport mechanisms, as ATP may be required for primary active transport (against gradient), secondary active transport (co-transport) or pinocytosis 4. Pinocytotic Vesicles - Pinocytosis ('cell-drinking') is the non-specific uptake of fluids and dissolved solutes (a quick way to translocate in bulk), hence these materials will be ingested via the breaking and reforming of the membrane and then contained within a vesicle
Measuring microscopic specimens:
1. To be able to work out the size of a field of view under the microscope you need to use a microscopic ruler called a stage micrometer to calibrate a set of divisions that remains permanently in the eyepiece. The latter is called an eyepiece scale. 2. The smallest division on the stage micrometer represents 10um. You can use this to calibrate the eyepiece scale. 3. In the case of the image above 20 divisions on the stage micrometer correspond to 30 divisions on the eyepiece scale and so 200 x 10 micrometers corresponds to 30 divisions on the eyepiece. And so 200 micrometers divided by 30 = 6.66 micrometer. So each divisions on the eyepiece at this magnification is 6.66 micrometers. 4. The procedure has to be repeated (once only) to calibrate at different magnifications. 5. You might remember from much earlier in the year that if you know the magnification of an image you can also find the actual size. 6. First measure the distance in mm from the middle of a light band to the middle of a light band ten light bands away and then convert to micrometers. Divide your answer by 10 for the length of one sarcomere. If you measured in mm then convert to micrometers (divide by 1000). 7. If this image is magnified 200x then you can calculate the actual length of a one sarcomere by dividing the answer above by 200. 8. 20 divisions of the stage micrometer= 200um --> 30 dimensions (lines) on eyepiece = 1 division on eypiece = 200 / 30 = 6.66um.
Propagation of an action potential:
1. To propagate an action potential means to generate more action potentials along the length of the axon. 2. This happens due to the movement of sodium ions. 3. Depolarisation reduces the concentration of sodium ions outside an axon and increases the concentration inside. 4. The depolarised region of the axon membrane has a different sodium ion concentration than its neighbouring/adjacent region which is still in the resting state. 5. Inside the axon the sodium ions diffuse laterally (sideways) to a neighbouring region that has lower sodium ion concentrations. 6. This lateral movement has an effect on the neighbouring area that is in resting potential. 7. The resting potential in this area rises from -70mv to approx -50mv and this is enough to open the sodium channels in the region of the membrane still in resting potential and to allow an action potential to form in this region. 8. As these channels are sensitive to voltage they are called voltage gated channels. 9. The action potential will only be generated when the electrical potential reaches -50mv. This value is called the threshold potential.
Other pathogens can cross species barriers, so can be transmitted from infected members of one species to uninfected members of another species. Examples:
1. Tuberculosis can infect both cattle and badgers and can pass in milk from cattle to infect humans; rabies can pass from infected dogs to humans. 2. A disease that can be passed to humans from other animals is called a zoonosis.
Nephron Function: Nephrons filter blood and then reabsorb useful materials from the filtrate before eliminating the remainder as urine This process occurs over three key stages:
1. Ultrafiltration - Blood is filtered out of the glomerulus at the Bowman's capsule to form filtrate 2. Selective reabsorption - Usable materials are reabsorbed in convoluted tubules (both proximal and distal) 3. Osmoregulation - The loop of Henle establishes a salt gradient, which draws water out of the collecting duct
Urine testing
1. Urine testing is very common as can be used to indicate disease or the use of recreational and/or performance enhancing drugs. Common urine test include: 2. Glucose testing - a positive result is indicative of diabetes 3. Protein testing - small amounts are normal e.g. HCG or insulin. Large amounts of proteins are indicative of a problem with the ultra filtration mechanism in the kidney. 4. Blood cells - the presence may indicate a variety of diseases including urinary tract infections and some cancers e.g bladder cancer. 5. Drugs - many drugs (or their metabolic byproducts) pass out of the body in urine and so tests can indicate there consumption. Marijuana, cocaine, heroin and amphetamines can all be detected in urine analysis
Herd Immunity
1. Vaccinations programmes are implemented to reduce the outbreak of particular infectious diseases within populations 2. An epidemic is a substantially increased occurrence of a particular infection within a given region 3. A pandemic is an epidemic that has spread across a large geographical area (like a continent) 4. Vaccination confers immunity to vaccinated individuals but also indirectly protects non-vaccinated individuals via herd immunity 5. Herd immunity is when individuals who are not immune to a pathogen are protected from exposure by the large amounts of immune individuals within the community
Early embryological development
1. Within about 7 days numerous cycles of mitosis has produced a cluster of approx. 125 cells. 2. Within this cluster there is migration of cells to particular locations giving the embryo the shape of a hollow ball called a blastocyst. ("Blastos" is from the Greek "to sprout" and "kustis" from Greek meaning "bladder", to denote an enclosed fluid filled sac/structure - you will have heard of "cysts" in medicine. 3. The blastocyst has used up the reserves of the egg cell and needs an external supply of food. The zona pellucida breaks down and the blastocyst rests on the endometrium (endo for inside,"metrium" is Latin for womb). This is called implantation. The outer layer of the blastocyst develops finger like projections that penetrate the uterus lining. 4. Food and oxygen are absorbed across the finger like projections which fuel further embryo growth. Without successful implantation pregnancy will not continue.
How does smoking become a problem (and emphysema occurs)?
1. You damage the elastin (found in the basement membrane surrounding the Alveoli) --> smokers damage the elastin = you can not expel air easily from the lungs = air doesn't easily go out = very small shallow breaths, but can't get out the old air. 2. Emphysema causes that you have more air in your lungs, but you can't get it out. 3. Higher volumes of air left in your lungs after you exhale - leaves very little room in the alveoli for new, fresh air. 4. When you smoke your body sends lots of phagocytes (white blood cells aka. leukocytes) to try and ingest all the stuff that is not supposed to be in your lungs (from the smoke). 5. The phagocytes will release an enzyme to try and digest proteins in the pathogens, aka protease (elastase) enzymes. 6. You are now releasing a lot more protease enzymes into your lungs than you normally would, even though your body has a defense system against protease (elastase) enzymes and produce an antiprotease chemical to try and stop damage to our own cells, but if you smoke, chemicals affect the ability of the antiprotease chemical to stop the protease from doing any damage. 7. Now you are making too much protease (elastase) and the antiprotease doesn't work properly. So you very quickly begin to degrade the elastin surrounding your alveoli - they loose their shape, get thicker (less permeable) walls and decrease their surface area (important for gas exchange) = you now have emphysema. 8. The alveoli looses their intricate shape and form big clumps, merge together almost, which causes the surface area to decrease (less area for gas exchange), but the volume to increase and cause air to get trapped = air in the lungs does not get deoxygenated fully = capacity diminished (why you have the short, shallow breaths) + you don't have the recoilability from elastin to take in lots of new, fresh air.
Zoonosis (zoo = animal & nosis = disease)
1. Zoonosis (zoo = animal & nosis = disease): An infectious disease that is transmissible from animals to humans. 2. Eg. SARS (most recent is COVID-19), rabies (dogs), bird flu, lime disease (from ticks into humans), swine flue, cow pox, etc. 3. The more humans expand to previously uninhabited land = the greater the chance they get infected with zoonotic diseases.
As the secretory cells are actively involved in protein production they will have:
1. abundant rER 2. abundant Golgi apparatus 3. abundant mitochondria 4. abundant secretory vesicles moving toward the plasma membrane for exocytosis.
Consequences of lung cancer include:
1. chest pain 2. difficulty breathing 3. coughing 4. coughing up blood 5. unexplained fatigue 6. weight loss 7. appetite loss. (Lung cancer survival rate are 15% beyond 5 years. Treatment often involves surgery to remove the affected lung region followed by chemo and/or radiotherapy. Even those that are cured are likely to have future impaired lung function, pain and may suffer anxiety over the disease returning.)
Type 1 Diabetes
1. early sudden onset in childhood, inability to secrete enough insulin 2. autoimmune caused by destruction of Beta cells (Islets of Langerhans) by immune system 3. treated by regular testing of blood sugar levels and injecting insulin if sugar is too high. 4. possibility of stem cells becoming functional beta cells as a cure
Explain how skeletal muscle contracts:
1. muscles/fibres/myofibrils contain (repeating) units called sarcomeres; 2. muscle/sarcomeres contain actin filaments and myosin filaments; 3. actin fibres are thin and myosin fibres are thick; 4. arriving action potential causes release of calcium ions; 5. from sarcoplasmic/endoplasmic reticulum; 6. calcium ions bind to troponin; 7. causing troponin and tropomyosin to move (on actin); 8. exposing binding sites on actin / for myosin; 9. ATP binds to myosin heads releasing them / breaking cross bridges; 10. ATP hydrolysed / split into ADP + P ; 11. ATP/energy causes myosin heads to change shape / swivel / become cocked; 12. myosin heads bind / form cross-bridges to (exposed) actin binding sites; 13. myosin heads swivel / move actin (releasing ADP + P ); 14. myosin filaments move actin filaments towards centre of sarcomere; 15. sliding of filaments / actin and myosin shortens the sarcomere;
What are functions of the stomach, small intestine and large intestine?
A
What enzyme can be found in mucus located in mucus membranes? A. Amylase B. Lysozyme C. Elastase D. Antibodies
B. Lysozyme
What is a feature of the human circulatory system? A. The wall of the right ventricle of the heart is the thickest of the four chambers. B. The pulmonary artery and vena cava both carry deoxygenated blood. C. Valves are found in arteries and veins but not capillaries. D. Epinephrine acts on the pacemaker to reduce heart rate.
B. The pulmonary artery and vena cava both carry deoxygenated blood.
What is a role of the coronary arteries? A. To supply information about blood temperature to the hypothalamus B. To supply the heart muscle with oxygen and nutrients C. To carry blood away from the heart D. To monitor blood pH
B. To supply the heart muscle with oxygen and nutrients
The graph shows a correlation between the number of new cases of stomach cancer and vegetable consumption for women in Poland. What can be stated from the graph? A. Vegetable consumption causes stomach cancer B. 68 % of the data are gathered around the trend line C. Causality cannot be stated from the graph alone D. Only that the correlation is positive
C. Causality cannot be stated from the graph alone
The graph is about defence against infectious disease. What is likely to be indicated by the letter X? A. The increase in lymphocytes following HIV infection B. The peak of the infection C. The secondary response to a vaccine D. The first appearance of AIDS symptoms
C. The secondary response to a vaccine
Which statement is true for the antibiotic penicillin? A. Watson and Crick developed the usage of penicillin. B. Penicillin blocks processes unique to eukaryotic cells. C. Viruses lack metabolism and penicillin has no effect on them. D. Florey and Chain sequenced the genome of Penicillium notatum.
C. Viruses lack metabolism and penicillin has no effect on them.
What happens to starch in the small intestine? A. Endopeptidase secreted by the liver digests starch to enable absorption by the villi. B. Contraction of intestinal muscle mixes starch with enzymes to accelerate its conversion into amylose. C. Glycogen secreted by the pancreas hydrolyses starch into glucose, which is eventually transported to the liver. D. Amylase secreted by the pancreas digests starch to enable absorption by the villi.
D. Amylase secreted by the pancreas digests starch to enable absorption by the villi.
What is shown here?
The ultrastructure of the glomerulus ("glomus" is Latin for a "ball of thread") and the Bowman's capsule is shown.
Arteries 1. Arteries carry blood at high pressure (80 - 120 mm Hg) 2. They have a narrower lumen (to maintain high pressure) surround by a thick wall made of two layers 3. The middle layer (tunica media) contains muscle and elastin to help maintain pulse flow (it can contract and stretch) 4. The outer layer (tunica adventitia) contains collagen prevents the artery rupturing due to the high pressure blood flow Veins 1. Veins carry blood under low pressure (<10 mm Hg) 2. They have a very wide lumen (keeps pressure low and allows greater flow of blood) 3. The walls of tissue surrounding the vein are thin (blood is not travelling in rhythmic pulses) 4. They have valves to prevent blood pooling at extremities (arteries do not have valves) Capillaries 1. Capillaries are involved with material and gas exchange with the surrounding body tissue 2. Blood pressure in the capillaries is relatively low (~15 mm Hg) and they have a very small diameter (~5 micrometers wide) 3. Their wall is made up a a single layer of cells to allow for ease of diffusion 4. Capillaries may contain pores to aid the transport of material
Explain the relationship between the structure and function of arteries, capillaries and veins
1. arteries carry blood away from the heart / to tissues; 2. arteries have thick walls to withstand high pressure / prevent bursting; 3. arteries have muscle fibres to help pump blood; 4. arteries have elastic fibres to allow artery wall to stretch/recoil; 5. capillaries allow exchange of O2 / CO2 / nutrients / waste products from tissues/cells; 6. capillaries have a thin wall to allow (rapid) diffusion / movement in / out; 7. capillaries have pores to allow phagocytes / tissue fluid to leave; 8. capillaries are narrow so can penetrate all parts of tissues / bigger total surface area; 9. veins carry blood back to the heart / from the tissues; 10. veins have thinner walls because the pressure is low / to allow them to be squeezed; 11. veins have fewer muscle / elastic fibres because there is no pulse / because pressure is low; 12. veins have valves to prevent backflow; 13. veins have large lumens to accomodate the slow moving blood;
Explain the relationship between the structure and functions of arteries, capillaries and veins. [9]
1. Antibiotics are substances or compounds that kill or inhibit the growth of bacteria by targeting the metabolic pathways of prokaryotes 2. Specific prokaryotic features that may be targeted by antibiotics include key enzymes, 70S ribosomes and the bacterial cell wall 3. Because eukaryotic cells do not have these features, antibiotics can kill bacterial cells without harming humans (or viruses) 4. Virus do not carry out metabolic reactions themselves but instead infect host cells and take over their cellular metabolisms 5. Viruses need to be treated with specific antiviral agents that target features specific to viruses (e.g. reverse transcriptase in retroviruses)
Explain why antibiotics are effective against bacteria but not against viruses
1. The discovery of Penicillin is one of the most important in medicine. (However, it was not until ten years after its discovery by Alexander Fleming in 1928 that the benefits of penicillin were actually realised. Howard Florey and Ernst Chain were able to produce enough penicillin in 1940 to experiment with its effects on mice.) 2. In the experiment, Florey & Chain injected 8 mice with a lethal suspension of bacteria. 4 of these mice were also given penicillin. 3. The 4 mice which received penicillin lived and all the rest died, giving definite proof that penicillin worked as an antibiotic against serious bacterial infections. (It was this test which set Florey, Chain and others on the long road to purifying and mass producing penicillin. The first human to receive penicillin was in 1941 to treat an infection caused by a scratch from a rose bush thorn on the face of a policeman called Albert Alexander. Although his condition improved the lack of penicillin meant that the infection returned and he subsequently died. Below is an image of Albert.) 5. Note that under current testing regulations human testing would not be allowed after such minimal animal testing. 6. Testing in humans first studies tolerance, side effects and dosage levels in healthy volunteers, then onto small scale testing of patients with illness, then large scale testing in double blind trials. A double blind trial means that the patients and the medical personnel are unaware of who is getting the active drug and who is getting a placebo (a substance with no medical use). (By 1945, after an immense effort by both American pharmaceutical companies as well as the governments of the UK and the USA there was enough penicillin to treat all allied war casualties.)
Florey & Chain's Experiment:
How would you measure this in practice?
In practice, using a microscope in a laboratory, it would be useful to have a permanent "scale" that remains in the eyepiece of the microscope. The eyepiece is a permanent fixture. You first must calibrate the scale in the eyepiece using another "ruler" of known length divisions that sits on the stage of the microscope. This is called a stage micrometer. Once you have calibrated the scale on the eyepiece you can remove the stage micrometer and then replace it with your specimen e.g. a muscle slide. This is what it may look like under a microscope. Remember, the stage micrometer has known divisions. The eyepiece scale does not. The latter needs to be calibrated. Let's say that the smallest divisions of the stage micrometer are 10um. Find a region where one line on the eyepiece scale matches up with a line on the stage micrometer. In the example above 20 divisions on the stage micrometer match up with 30 divisions on the eyepiece scale. Therefore 20 x 10um = 30 divisions on the eyepiece scale. And so 200um = 30 divisions and so 1 division on the eyepiece is 200/30 = 6.66um. You can now remove the stage micrometer and use your eyepiece scale to measure the size of an actual specimen on a slide. Note that if you change the magnification of the microscope you need to repeat the entire process.
non-specific immunity to disease
Ingestion of pathogens by phagocytic white blood cells gives
the build up of fatty tissue in the artery wall beneath the endothelium/inner layer. LDLs (containing fats/triglycerides and cholesterol) become embedded with dead phagocytes, collagen and calcium and the artery wall begins to bulge into the lumen.
The occlusion is caused by
What is the cervix?
The opening to the uterus
enzymes into the lumen of the small intestine
The pancreas secretes _____
skeletal muscle groups, which facilitate venous blood flow via periodic contractions
Veins typically pass between
Epithelium
Very inner cell layer of the mucosa in contact with the food (contains very specialised cells for moving food in the bloodstream).
1. Blood clotting occurs when a blood vessel is damaged. It prevents exit of blood and entry of pathogens. 2. It involves a cascade/sequence of reactions where the product of the first reaction is an enzyme for the second reaction and so on. It therefore is a very rapid process. 3. It begins with thrombocytes (sometimes called thromboplasts to indicate that they are "clotting platelets") starting to adhere/stick to exposed collagen fibres in the walls of the damaged blood vessels. 4. A temporary "platelet plug" forms at the site of the damage. Note that another name for a platelet is a thrombocyte - "thrombus" for clot, "cyte" for cell. 5. This initial temporary platelet plug is followed rapidly by the formation of a fibrin ("chemical that forms fibres") blood clot. 6. Proteins called clotting factors are released by the blood platelets. These trigger a cascade/series of reactions. 7. The final product is a fibrin mesh. This traps erythrocytes which begin to dry out and plug/seal the cut in a more permanent fashion. 8. Prothrombin activator is a clotting factor.
What is blood clotting?
1. He was a surgeon who observed cowpox could provide immunity for smallpox (which is now the first disease humans have eradicated). 2. Milkmaids who contracted cowpox (milder) would not develop smallpox (because they are very similar, as their antigens are the same). 3. The vaccine used the cowpox virus (shown below - note the scale bar) to provide protection against the deadly smallpox virus, hence the name. 4. Both viruses are similar enough that the memory cells against cowpox virus also recognise antigens on the surface of the smallpox virus. (5. 18th-19th century --> The ethics of Jenner's experiment were such that they would certainly not be allowed nowadays. He deliberately injected a healthy boy, called James Phipps, with a deadly virus without fully knowing what the consequences might be and without the consent of the boy or his guardians. He had previously infected the boy with cowpox and suspected that he should now be immune to smallpox. A code of ethics for human research subjects was adopted after the infamous Nazi medical experiments on children in WWII. --> An estimated 300 million people died from smallpox in the 20th century alone. An estimated 60-90% of the Inca population and similar numbers of Aztecs. It was declared globally eradicated in 1979.)
Who was Edward Jenner?
Describe the process of endocytosis. [5]
a. (plasma) membrane encloses/engulfs solid particles/droplets of fluid/molecules;b. fluidity of the membrane allows endocytosis;c. plasma membrane forms pit/forms indentation/pulled inwards/invaginates;d. membrane pinches off/seals back on itself/edges fuse;e. vesicle/vacuole formed;f. inside of plasma membrane becomes outside of vesicle membrane / converse;g. vesicle breaks away from plasma membrane/moves into cytoplasm;h. active process / endocytosis/vesicle formation requires energy; [5 max]Accept any of the above points clearly described in an annotated diagram.(Plus up to [2] for quality)
Describe the processes involved in absorbing different nutrients across the cell membrane of villus epithelium cells lining the small intestine.[4]
a. (simple diffusion) of nutrients along/down a concentration gradient ✔b. example of simple diffusion eg fatty acids ✔c. facilitated diffusion of nutrients involves movement through channel proteins ✔d. example of nutrient diffusion eg fructose ✔e. active transport of nutrients against a concentration gradient / involving protein pumps ✔f. example of active transport, eg (iron) ions/glucose/amino acids ✔g. endocytosis / by means of vesicles ✔h. example of nutrient for endocytosis, eg cholesterol in lipoprotein particles ✔
Maternal arteriole
brings hormones from mom, oxygen, nutrients and vitamins.
Right before the lungs, the trachea splits in two, forming two ______.
bronchi (singular="bronchus"). The bronchi go into a lung each.
Within the lungs, the bronchi split into many smaller and smaller branches, known as _______.
bronchioles. This can be thought of like an upside-down tree.
What is the sequence of structures through which a molecule of oxygen will pass during its entry into the body?
bronchus > alveolus > pulmonary vein
Internal fertilization offers more protection to the gametes and embryos,
but at a potential survival cost to the parent
The pancreas also releases
nucleases which digest nucleic acids (DNA, RNA) into smaller nucleosides.
Breeding experiments showed that the obese mice had two copies of a recessive allele, ____.
ob/ob.
Circadian rhythms are
the body's physiological responses to the 24 hour day-night cycle
The human elbow joint is an example of a hinge joint that is located between
the humerus and radius / ulna
The larger the medulla =
the larger the loop of henle
Carbohydrate digestion begins in
the mouth with the release of amylase from the salivary glands (amylase = starch digestion).
It is important to get the "air" out of your lungs to get
the new fresh "air", because the "air" that is newly inhaled has a greater amount of oxygen than the air in your blood, which makes the diffusion gradient greater for gas exchange between air in (high in O2 and low in CO2) and air out (lower O2 and higher CO2). = you must constantly bring in fresh air to keep the diffusion gradient high. = ventilation (replace the "old" air with "new" air) = ventilate your lungs (remove old / stale / air high in CO2 & low in O2 and bring in new / fresh / air high in O2 & low in CO2).
Starch digestion by amylase does not occur in the stomach as
the pH is unsuitable (too acidic) for amylase activity (optimal pH ~ 7).
Blood enters the kidneys via
the renal artery and exits the kidneys via the renal vein
The composition of blood in the renal artery is different from that in
the renal vein
Explain how nerve impulses are transmitted along and between neurons. [9]
the resting potential of cell is negative inside compared with outside;stimulation causes depolarization/reversal of charge on each side;due to Na channels opening / Na flowing into the cell;which causes an action potential;K channels open / K flows out of the cell;sodium potassium pump restores resting potential;transmitted between neurons across a synapse;neurotransmitter released into synaptic cleft;diffuse across cleft to postsynaptic membrane;where they bind to receptors;influx of Na into cell;which may initiate action potential; [9 max]
The type of enzyme secreted and location of secretion depends on
the specific macromolecule required for hydrolysis