Stage 1 Biology: Multicellular Organisms

Explain gas exchange at the body's cells:

After being pumped from the left side of the heart, oxygen-rich blood reaches the body cells: - the oxygen concentration is high in the blood and low in the cells (so oxygen is diffused into the cells) Meanwhile; - carbon dioxide concentration is low in the blood and high in the cells (so CO2 diffuses into the blood and is transported back to the lungs to the alveoli)

Why is important for exchange surfaces to have a large surface area?

Allows efficient exchange of materials (greater sites to exchange across therefore more channels/carriers with larger SA) Microvilli on exchange surfaces further increase the surface area.

Overview of arteries: 1. oxygen and carbon dioxide content 2. direction of blood flow 3. Amount of muscle and elastic tissue 4. Blood pressure 5. Size of Lumen 6. Presence of valves

Arteries: 1. rich in oxygen, poor in carbon dioxide 2. away from the heart 3. high amount of muscle/elastic tissue 4. high blood pressure 5. narrow lumen size 6. do not have valves

Explain gas exchange at the alveoli:

At the alveoli... We breathe in: - oxygen concentration is rich in the alveoli and poor in the blood capillary (so oxygen moves from the alveoli into the capillary by diffusion) Meanwhile; - carbon dioxide concentration is low in the alveoli and rich in the blood capillaries (so CO2 moves into the alveoli by diffusion) We breathe out.

What is bile?

Bile is a substance made in the liver and stored in the gall bladder

How does bile work?

Bile is released into the first part of the small intestine (duodenum) and neutralises acids from the stomach. It physically breaks up fat globules into smaller globules to increase surface area, allowing more chemical digestion by lipase

Overview of capillaries: 1. oxygen and carbon dioxide content 2. direction of blood flow 3. Amount of muscle and elastic tissue 4. Blood pressure 5. Size of Lumen 6. Presence of valves

Capillaries: 1. At artery end - rich in oxygen and poor in carbon dioxide At vein end - rich in carbon dioxide and poor in oxygen 2. from arteries to veins 3. no muscle/elastic tissue 4. low blood pressure 5. narrow size of lumen 6. do not have valves

State the hierarchy of an organism:

Cells make up tissues, tissues make up organs, organs make up organ systems which make up organisms!

What is the function of nerve tissue?

Communication

Describe and provide an example of diffusion

Diffusion is a passive process (no energy is required) Many substances move across exchange surfaces through diffusion from high concentrations to low concentrations. e.g. CO2 and O2 between capillaries and alveoli

What is the difference between embryonic stem cells and adult stem cells?

Embryonic stem cells have the ability to differentiate into any of the 230+ types of cells in the body whereas adult stem cells have limited ability to differentiate into different cell types (i.e. adult stem cells in the gut divide and differentiate into the epithelial cells to replace the gut lining every 2-5 days but can't differentiate into cardiac muscle or white blood cells etc.)

How are epigenetics controlled?

Epigenetic tags (methyl groups) an be added and removed based on our lifestyle, which changes the genes that are switched on and off

What is epigenetics?

Epigenetics is a second layer of coding on top of the DNA base sequence

Why are all cells genetically identical?

Every cell in an organism is genetically identical because they were all formed from the zygote through mitosis maintaining identical chromosomes in each cell

Make comments about the following factors in the process of exhalation: a) Diaphragm shape b) Ribs c) Diaphragm Muscle d) Rib Muscle e) Lungs f) Volume of chest cavity g) Air pressure in lungs

Exhaling: a) diaphragm makes a dome shape b) Ribs move down and in c) diaphragm muscle relaxes d) rib muscle relaxes e) lungs deflate f) volume of chest cavity decreases g) air pressure in lungs increases

What is the process of filtration?

Filtration occurs between the glomerulus and the Bowman's capsule. All substances that are small enough to fit through the walls of the capillaries and into the bowman's capsule are filtered, regardless if the substances are useful or wasteful

Why is important for exchange surfaces to have an extensive blood supply?

For transport and maintaining the concentration gradient needed for diffusion

Why is important for exchange surfaces to be moist?

If they dry out, they will die and become impermeable. Also, these substances only diffuse through membranes as solutes (i.e. dissolved in water)

How are cells epigenetically different?

Individual cells can have different epigenomes - the epigenetic tags can be switched on/off, giving rise to different cell types

Make comments about the following factors in the process of inhalation: a) Diaphragm shape b) Ribs c) Diaphragm Muscle d) Rib Muscle e) Lungs f) Volume of chest cavity g) Air pressure in lungs

Inhaling: a) diaphragm flattens b) Ribs move up and out c) diaphragm muscle contracts d) rib muscle contracts e) lungs inflate f) volume of chest cavity increases g) air pressure in lungs decreases

Describe where lipids are absorbed.

Lipids are broken down into glycerol and fatty acids and are absorbed across the villi into the lymph vessel known as the lacteal.

What are lipids broken down into?

Lipids are broken down into glycerol and three fatty acids

What is the difference between mechanical (physical) and chemical digestion?

Mechanical digestion is the physical breakdown of food from large pieces into smaller pieces. Chemical digestion involves enzymes, which break down large molecules into small molecules by breaking bonds

Give an example of an organ system and the organs it consists of

Mouth > oesophagus > stomach > small/large intestine > rectum > Angus > pancreas > liver > gall bladder

What is the function of muscle tissue?

Movement

How are lipids broken down?

Pancreatic lipase starts and finishes the chemical digestion of fats in the small intestine

How are proteins broken down?

Pepsin starts the chemical breakdown of proteins in the stomach and trypsin finishes it in the small intestine.

What is peristalsis?

Peristalsis is a wave of smooth muscle contractions that propel food bolus through the oesophagus and into the stomach. Peristalsis also churns stomach and propels chyme through small intestine

Which blood cell is the smallest and does not have a nucleus?

Platelets are the smallest and don't have a nucleus

What happens if a substance is not reabsorbed from the tubule black and into the blood capillaries?

it will end up in the urine. Therefore, useful substances need to be reabsorbed

What is another disease of the lungs, and how does it work?

pneumonia is a bacterial infection that infects the pleural membrane and increases fluid development reducing gas exchange sites (impairing oxygen supply to cells)

What are proteins broken down into?

proteins are broken down into amino acids

Describe where proteins are absorbed.

proteins are broken down into amino acids, which are absorbed across villi and into the blood capillaries.

What does the coronary artery do?

supply nutrients to the heart tissues

What is athlerosclerosis?

the hardening of the arteries caused by the deposit of lipids

What is the role of the pancreas? What does it do?

the pancreas produces pancreatic enzymes (pancreatic amylase, trypsin and pancreatic lipase) which is secreted into the duodenum

Provide an example that shows how tissues make up organs

the stomach consists of nervous, epithelial, connective (blood) and smooth muscle

Smokes contain over 69 chemicals that induce cancer. This can cause cancer in a person smoking tobacco, or those around the person. What effect does this have on our health system?

this increases the pressure on our health system and takes up beds in hospitals that other patients with non-preventable conditions could have instead.

How can too much exercise increase the risk of cardiovascular disease?

excessive exercise burn off excess fat and increase good cholesterol levels (HDLs) which collect bad cholesterols (from plaque build up and return to liver for processing)

Which type of cells are not genetically identical?

gametes (sex cells) ... contain 23 chromosomes as opposed to 46

What makes red blood cells efficient at transporting oxygen? (2)

- Red blood cells are biconcave in shape to increase surface area - Red blood cells don't have a nucleus so that they can pack in more haemoglobin in so that more oxygen can be transported

Describe the process of blood flow in and out of the heart

1. De-oxygenated blood flows in through the vena cava 2. The blood is forced into the right atrium and then the right ventricle through the atrioventricular valves, due to the contraction of the atrium 3. The blood pressure in the ventricles rise, causing the atrioventricular valves to shut, preventing backflow (LUBB) 4. This rise triggers the semi-lunar valves to open, and the blood flows into the pulmonary artery 5. Once the left ventricle finishes contracting, the blood pressure in the ventricle fails to close the semi-lunar valves and prevent backflow (DUBB) 6. The blood in the pulmonary artery travels to the lungs where it exchanges carbon dioxide for oxygen, and gets blood rich in oxygen 7. This oxygenated blood enters the pulmonary vein (goes therough the same process described as above (but in the left side of the heart) and exists via the aorta, to deliver nutrients to the cells

What are the 4 main types of tissues?

1. Epithelial 2. Connective 3. Muscle 4. Nerve

What are the three types of blood cells and their functions?

1. Red blood cells - transport oxygen to all body cells 2. White blood cells - defend body from pathogenic microbes and foreign materials 3. Platelets - help clot blood and prevent bleeding out

What are the 3 stages of athlerosclerosis?

1. the gradual build up of fatty plaque on the inside of the arteries at weak points due to the elevated bad cholesterol levels 2. Plaque continues to thicken, which hardens the arteries and narrows blood flow, placing pressure on the heart 3. the blood vessel becomes almost completely blocked, which deprives cells of oxygen and blood. This causes an increased risk of blood clots, heart attacks, strokes and chest pain, due to the lack of oxygen to the heart and brain

Usually, 100% of what is reabsorbed?

100% of glucose and amino acids are reabsorbed

Usually, 50% of what is reabsorbed?

50% of urea is reabsorbed (waste product that is excreted into the urine) Most proteins are too big to be filtered

Usually, 99% of what is reabsorbed?

99% of water is reabsorbed (otherwise we would dehydrate) But this differs based on the needs of the body

How does a poor diet increase the risk of cardiovascular disease?

A poor diet, that is high in saturated fat, can elevate bad cholesterol levels (LDLs) and increase the chance of plaques and blockages forming. Additionally, a diet high in salt/sugar can increase blood pressure and increase the risk of damage to internal blood vessel lining, creating more chance of plaques developing and the hardening of arteries

Define tissue.

A tissue is a collection of similar cells grouped together to perform a specific function

Describe the role of ADH in water reabsorption

ADH acts on the kidneys and increases aquaporins inserted in the collecting duct, which results in increased water reabsorption... This means that there is less water being excreted in the urine, resulting in more concentrated urine (and less chance of a person dehydrating)

Describe where carbohydrates are absorbed.

After being broken into glucose and being absorbed across villi into the blood capillaries.

Label the diagram of the heart

done

Label the organs of the digestive system.

done

Label the parts of the respiratory system.

done

What is the structural unit of the kidneys? Label this.

done

How can a lack of exercise increase the risk of cardiovascular disease?

as lack of exercise means a lack of burning energy. This can result in obesity and more fats circulating in the blood

What is the difference between specialised and unspecialised cells?

STEM Cells are unspecialised cells that have not yet differentiated into specialised cells. These cells can differentiate into any type of specialised cell. Specialised cells have a specific structure and function. These cells can only divide by mitosis into more of the same cell and cannot differentiate into another type of cell. (i.e. red blood cells are bi-concave in shape and transport oxygen - they have a different structure and function to muscle cells)

How are carbohydrates broken down?

Salivary amylase starts chemical digestion of carbs in the mouth, and pancreatic amylase finished the digestion in the small intestine

What are complex carbs (such as starch) broken down into?

Simpler carbohydrates such as glucose

What is a disease that smoking causes, and what does this disease do?

Smoking causes emphysema, which is the irreversible destruction of the alveoli. Emphysema reduces the surface area of the lungs, which reduces gas exchange sites

Why do stem cells differentiate into specialised cells?

Stem cells can differentiate into specialised cells due to hormones or epigenetic tags (i.e. genes associated with making new nerve cells are activated in nerve cells but are not activated in skin cells)

How do stem cells become specialised?

Stem cells differentiate into specialised cells due to specific cells being 'switched on' or activated.

Which blood vessel can substances be exchanged across

Substances can only be exchanged across capillaries

Where does the blood take such glucose from this point?

The blood in the capillaries are taken to the liver for processing, in which it can be redirected into blood for immediate use of cells, or glycogen or converted into fat (if stores are full)

Where does the blood take such amino acids from this point?

The blood in the capillaries is taken straight to the liver for processing, in which it can then be redirected into blood for immediate use of cells. Or proteins can be broken down to create energy if there is a lack of glucose etc. creating urea that is removed via the excretory system

What happens if epigenetic tags occur in sex cells?

The epigenetic tags can be passed onto future generations

Why is important for exchange surfaces to be thin?

The extremely thin, angular layer of epithelial cells allow substances to pass through minimal disruption (less distance to travel)

Discuss the roles of the large intestine, rectum and anus.

The large intestine absorbs water from the stool and propels stool to the rectum. The rectum stores the stool. The anus releases the stool.

Which side of the heart is thicker and why?

The left side of the heart is thicker than the right side because it has to pump the blood to all cells in the body at high pressure (head to toes) whereas the right side only pumps blood into the lungs (less distance)

Where are such glycerol and fatty acids taken from this point?

The lymph system bypasses the liver and eventually they enter the circulatory system where they are delivered to cells for use or adipose tissue for storage.

What is the difference between atrioventricular valves and semi-lunar valves?

The two atrioventricular valves open to allow blood to move from the atria to the ventricles and close to prevent back flow into the atria when the ventricles contract to push blood out of the arteries through the two semilunar valves

What are the four features of exchange surfaces?

Thin Moist Large surface area Blood supply

What is the function of epithelial tissue?

To cover and protect (i.e. the lining of the inner stomach to protect it from acid)

What is the function of connective tissue?

To provide support and join tissues

Overview of veins: 1. oxygen and carbon dioxide content 2. direction of blood flow 3. Amount of muscle and elastic tissue 4. Blood pressure 5. Size of Lumen 6. Presence of valves

Veins: 1. rich in carbon dioxide, poor in oxygen 2. towards the heart (back into) 3. low amount of muscle/elastic tissue 4. low blood pressure 5. wide lumen size 6. has vavles

What is the structure of villi and what is the their role in the small intestine?

Villi are finger like projections that have their own capillary network and a nymph vessel called a lacteal. They increase the surface area of the small intestine, increasing absorption sites.

Which blood cell is the largest and contains a nucleus?

White blood cells have a nucleus and are the largest