CHAPTER 42
Compare the respiratory systems of birds and mammals, explaining the greater efficiency of oxygen exchange in birds.
BIRDS have eight or nine air sacs that function as bellows that keep air flowing through the lungs. Air passes through the lungs in one direction only. Every exhalation completely renews the air in the lungs MAMMALS ventilate their lungs by negative pressure breathing, which pulls air into the lungs. Lung volume increases as the rib muscles and diaphragm contract
Explain how blood returns to the heart, even though it must sometimes travel from the lower extremities against gravity.
Bp in head is 27mm Hg less then heart -> if lower=faint -> fall head close to heart Challenge for long necked animals Mechanisms that assist the return of venous blood to heart -1)Rhythmic contractions of smooth muscles in walls of venules & veins (aid in movement of blood) -2)Contraction of skeletal muscles during exersize(squeezes blood through veins toward heart. prevents blood clots=important) -3)Change in pressure w/in thoracic (chest) cavity during inhalation (causes venae cavae & other large veins near heart to expand & fill w/blood
Describe countercurrent exchange in fish gills. Explain why it is more efficient than the concurrent flow of water and blood.
COUNTERCURRENT EXCHANGE: blood flows opposite direction in which water passes over gills --maintains constant [] gradient for oxygen between blood and water passing over gill surface --remove more than 80% of O2 dissolved in water CONCURRENT FLOW (with blood and water moving in same direction) would result in drop to 50% or < removal
Relate the structures of capillaries
Microscopic vessels with very thin porous walls -CAPILLARY BEDS: networks of capillaries that infiltrate each tissue, passing within a few cell diameters of ever cell in the body. -chemicals (ex. dissolved gases) exchanged by diffusion between the blood and interstitial fluid around the tissue cells -at "downstream end" they converge into venules -walls=endothelium + basal lamina (1 layer)
Describe the advantages and disadvantages of air as a respiratory medium and explain how insect tracheal systems are adapted for efficient gas exchange in a terrestrial environment.
air--Oxygen easy to obtain but respiratory surfaces have difficulty remaining moist which is vital. Tracheal systems operate off diffusion of gases from area of high concentration to low concentration. Openings are limited in size to outside world to cut down on moisture loss. Respiratory surfaces must remain moist in order for gas exchange to take place efficiently.
Define a cardiac cycle, distinguish between systole and diastole, and explain what causes the first and second heart sounds.
contracts=pumps blood relaxes=chambers fill up with blood CARDIAC CYCLE: one complete sequence of pumping and filling SYSTOLE: contraction phase of cycle DIASTOLE: relaxation phase
Compare positive and negative pressure breathing. Explain how respiratory movements in humans ventilate the lungs.
NEGATIVE PRESSURE BREATHING works like a suction pump pulling air, instead of pushing it, into the lungs (mammals) POSITIVE PRESSURE BREATHING forces air down the trachea (amphibian) DURING INHALATION, contraction of rib cage causes it to expand while diaphragm contracts and descends --lungs expand and pressure inside them is lowered --air pressure now lower than in atmosphere --air rushes into nostrils and down breathing tubes DURING EXHALATION, rib muscles and diaphragm relax --lung volume is decreased and pressure inside them > --air forced out of lungs
Explain the role of lymph nodes in body defense.
Organs that filter lymph and play an important role in the body's defense
Distinguish between a pulmonary and pulmocutaneous circuit.
PULMONARY CIRCUIT: if part of right side pump uses capillary beds involved in the lungs (Reptiles & Mammals) PULMOCUTANEOUS CIRCUIT: if part of right side pump uses capalaries in lungs & skin (Amphibians)
Describe the origin of SA node in the normal human heart.
SA node generates electrical impulses similar to those produced by nerve cells --impulses from SA node spread fast w/in heart tissue (bc cardiac muscle cells are electrically coupled through gap juntions) --impulses generate currents that are conducted to the skin via body fluids (ELECTROCARDIOGRAM- ECG or EKG medical test where electrodes are placed on skin to detect and record currents that are conducted to the skin
Using diagrams, compare and contrast the circulatory systems of fish, amphibians, non-bird reptiles, and mammals or birds.
See book Figure 42.5
Describe the composition of lymph
The colorless fluid, derived from the interstitial fluid, in the lymphatic system of vertebrates. Its composition is about the same as that of interstitial fluid.
Define blood pressure and describe how it is measured.
generally measured for an artery in the arm at the same height as the heart S/D SYSTOLIC PRESSURE is the pressure in the arteries during ventricular systole; it is the highest pressure in the arteries DIASTOLIC PRESSURE is the pressure in the arteries during diastole; it is lower than systolic pressure
For the human respiratory system, describe the movement of air through air passageways to the alveolus, listing the structures that air must pass through on its journey.
---LUNGS located in thoracic cavity, enclosed in sac of two layers that are held together by surface tension of fluid between them ---air entering nostrils is filtered by hairs, warmed, and moistened ---air travels through pharynx, through glottis, & into larynx (possesses vocal cords/functions as voice box) ---air enters cartilage-lined trachea that forks into two bronchi which further branch into finer bronchioles that dead-end in alveoli --alveoli lined with thin layer of epithelium which serves as respiratory surface ---O2 dissolves in moist film covering epithelium & diffuses across to capillaries covering each alveolus --CO2 moves in opposite direction by diffusion
Explain why blood flow through capillaries is substantially slower than blood flow through arteries and veins.
# of capillaries enormous -each artery conveys blood to so many capillaries that the total cross-sectional area is greater=decrease in velocity -blood travels 500x slower .1cm/sec compared to 48cm/sec Importatn bc; capillaries are the only vessels w/walls thin enough to prmit the transfer of substances between the blood & interstitial fluid --slow time allows exchange to occur Speeds up as it enters the venules & veins -> have smaller cross sectional area
List the heart valves in a human heart, describe their location, and explain their functions.
-4 valves in heart prevent backflow & keep blood moving in the correct direction -made of flaps of connective tissue -open when pushed from one side & close when pushed from the other types -ATRIOVENTRICULAR VALVE(AV)- lies between each atrium and ventricle --anchored by strong fibers that prevent them from turning inside out --pressure generated by the powerful contraction of the ventricles closes the AV valves keeping blood from flowing back into the atria --the 1st noise hear when listening to heart --recoil of blood against the closed AV valves -SEMILUNAR VALVES- at the 2 exits of heart; where aorta leaves L ventricle & where pulmonary artery leaves R ventricle --pushed open by the pressure generated during contraction of the ventricules --ventricles relax=pressure built up in the aorta closes the semilunar valves & prevents backflow --2nd sound you hear when listen to heart --recoil of blood against the closed semilunar valve
Describe how carbon dioxide is picked up at the tissues and carried in the blood.
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Explain how a gastrovascular cavity functions in part as a circulatory system.
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List the structural components of a vertebrate circulatory system and relate their structure to their functions.
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Describe the pathway of the impulses from the SA node in the normal human heart.
1. Impulses spread rapidly through wall of the atria (causes both atria to contract in unison) 2. During atrial contraction, the impulses originating in the SA node reach other autorhythmic cells (contract and relax repeadly w/out any signal from the nervous system) that are located in the wall between L & R atria 3. ATRIOVENTRICULAR (AV) NODE: a region of specialized heart muscle tissue between the left and right atria where electrical impulses are delayed for about .1 sec before spreading to both ventricles and causing them to contract. 4. signals from the AV node are conducted throughout the ventricular walls by specialized muslce fibers called budle branches and purkinje fibers.
Describe the composition and functions of plasma.
90-92% WATER 7-8% PROTEINS •Transport of substances, blood clotting, fighting disease, maintain pH 1% SALTS •Maintains osmotic pressure and pH
Discuss the advantages of open and closed circulatory systems.
ADVANTAGES OF THE OPEN SYSTEM • The open circulatory system requires less energy for distribution. This system is more suited to animals that have a slower metabolism and a smaller body. Due to the absence of arteries, blood pressure remains low, and oxygen takes longer to reach the body cells. If an organism has a low metabolism, meaning it is generally less active in such processes as locomotion, digestion and respiration, it has less of a need for oxygen. Also, since oxygenated blood takes more time to reach the extremities of the body, the open system is only feasible in smaller animals. ADVANTAGES OF THE CLOSED SYSTEM • The closed system operates with a much higher blood pressure. In addition, it is more efficient in that it uses much less blood for even higher and faster levels of distribution. Since oxygenated blood may reach the extremities of the body much faster than with an open system, organisms with a closed system may metabolize much faster, allowing them to move, digest and eliminate wastes much more quickly. In addition, due to the efficient distribution of antibodies, immune responses are much stronger, helping the body to fight off infection more powerfully.
Describe the advantages and disadvantages of water as a respiratory medium.
Advantages - simplist mode of respiration is through diffusion Disadvantages - low solubility of O2 in water, - temperature and salinity dependant - metabolic consumption of 02 depletes it from the immediate surrounding water
Relate the structures of arteries
Carry blood away from the heart to organs -ARTERIOLES: in the organs, arteries branch into these small vessels that convey blood to the capalaries. -carry blood from the heart to the capillaries -2 layers of tissue surround epithelium --outer layer of connecting tissue containing elastic fibers -> allow vessel to strech & recoil --middler layer of smooth muscle & elastic fibers --wall 3x as thick=strong ---accommodate blood pumped at high pressure ---elastic recoil helps maintain blood pressure when heart relaxes between contractions --Signals from the nervous system & hormones circulating in the blood act on the smooth muscle arteries, controlling blood flow to different parts of body.
Blood vessels
Central lumen(cavity) + endothelium + surronding tissue (differ) ENDOTHELIUM- a single layer of flattened epithelial cells that lines blood vessels arteries & veins- distinuguished by the direction they carry blood, not O2 content.
Distinguish between open and closed circulatory systems. List the three basic components common to both systems.
FUNCTIONS OF THE CIRCULATORY SYSTEM • The circulatory system consists primarily of blood, the heart and a network of blood vessels. The main functions of the circulatory system are gas exchange, hormone and nutrient distribution, as well as waste elimination. The heart pumps the blood throughout the body, which is transported by the blood vessels to the necessary tissues and organs. Gas exchange involves spreading oxygen throughout the body and removing carbon dioxide waste. Oxygen must be delivered to all functioning body cells in order for them to metabolize, or carry out their functions and activities. Blood also transports helpful nutrients and antibodies so that the body's immune system may be healthy and responsive. OPEN CIRCULATORY SYSTEM • The open circulatory system is the simpler of the two systems. Here, the heart pumps blood into open cavities, where blood vessels carry the blood throughout the body at a low pressure. There are two major differences between the open and closed system. First, the open system bathes all organs and tissues throughout the body with blood and, second, there are no arteries or major veins to increase blood pressure and direct distribution. Animals with an open circulatory system typically have lots of blood and low blood pressure. CLOSED CIRCULATORY SYSTEM • Larger and more active animals, including all vertebrates, have a closed circulatory system. This more complex system includes two major processes: pulmonary and systemic circulation. In the former process, deoxygenated blood is passed through the lungs in order to receive oxygen. Afterward, systemic circulation distributes the newly oxygenated blood throughout the body. In a closed circulatory system, blood is directed through arteries to veins throughout the body. As opposed to bathing all tissues and organs with blood, the blood remains in vessels and is transported at high pressures to all extremities of the body at a rapid rate. BOTH SYSTEMS HAVE THREE BASIC COMPONENTS: A circulatory fluid (blood or hemolymph) A set of tubes (blood vessels) A muscular pump (the heart)
Define gas exchange and distinguish between a respiratory medium and a respiratory surface.
GAS EXCHANGE: the intake of Oxygen and the expulsion of Carbon dioxide. In the capillaries of the alveoli, oxygen travels due to the concentration gradient into those capillaries. Carbon dioxide is then expelled from those capillaries. RESPIRATORY MEDIUM: is air for animals and water for fish. It is basically the substance through with living animals receive their oxygen. RESPIRATORY SURFACE: is where the gaseous exchange takes place. The oxygen and carbon dioxide move across the respiratory surface entirely by diffusion.
List the functions of leukocytes.
GRANULAR NEUTROPHILS •Neutrophils, or granulocytes, are white blood cells that attack the infection before other white blood cells. They are the most numerous of all leukocytes. EOSINOPHILS •Eosinophils are white blood cells that protect the body by killing and swallowing bacteria. If the eosinophil cannot enlarge enough to engulf the bacteria, it will attach itself and kill the organism. BASOPHILS •Basophils increase their numbers when the body has an infection, accumulating at the site of infection. They discharge serotonins and histamines to help increase blood flow and decrease inflammation. AGRANULAR LYMPHOCYTES •Lymphocytes are primarily responsible for helping the body's immune system. They consist of B and T cells. B cells release antibodies into the body's fluids, while T cells directly attack viruses. MONOCYTES •The monocytes' primary purpose is to help with immune defense and rebuild damaged tissue. They also produce proteins for the body and antigens, which stimulate antibody production.
Distinguish between hemocyanin and hemoglobin as respiratory pigments.
HEMOCYANIN: Arthropods and many molluscs, works with copper as the oxygen-binding component HEMOGLOBIN: Most vertebrates and some invertebrate, contained within erythrocytes, transports O2
Describe respiratory adaptations of aquatic animals.
Have the ability to move to constantly have water (respiratory medium) passing over their gills (respiratory surface)
Distinguish between pulmonary and systemic circuits and explain the functions of each.
PULMONARY: blood vessels that carry blood to and from the lungs The right side of the heart is the pulmonary circuit pump. Blood returning from the body is relatively oxygen-poor and carbon dioxide-rich. It enters the right atrium and passes into the right ventricle, which pumps it to the lungs via the pulmonary trunk. In the lungs, the blood unloads carbon dioxide and picks up oxygen. The fresh oxygenated blood is carried by the pulmonary veins back to the left side of the heart (left atrium). SYSTEMIC:blood vessels that carry the functional blood supply to and from all body tissues The left side of the heart is the systematic circuit pump. Freshly oxygenated blood leaving the lungs is returned to the left atrium and passes into the left ventricle which pumps it into the aorta. From there the blood is transported via smaller systemic arteries to the body tissues, where gases and nutrients are exchanged across the capillary walls. Then the blood once again loaded with carbon dioxide and depleted of oxygen, returns through the systemic veins to the right side of the heart, where it enters the right atrium through the superior and inferior venae cavae.
Describe the function of platelets.
THROMBOCYTES: responsible for the prevention of blood loss (used for clotting)
Describe the location and function of the sinoatrial (SA) node of the heart.
The pacemaker of the heart, located in the wall of the right atrium, near where the superior vena cava enters the heart, sets the rate and timing at which all cardiac muscle cells contract. o Generates electrical impulses that spread rapidly within heart tissue and bodily fluids o Causes the atria to contract in unison
Relate the structures of veins to their functions.
Vessesls that carry blood back to the heart -VENULES: small vessesls that convey that converge capalillaries into veins -return blood to the heart from the capillaries -EXCEPT the portal veins which carry blood between pairs of capillary beds. --Ex. hepatic portal vein carries blood from the capillary beds in the digestive system to capillary beds in the liver --from the liver, blood passes into the hepatic veins, which conduct blood toward the heart --thinner than arteries ---convey blood back to heart at lower velocity & pressure ---valves in veins maintain a unidirectional flow of blood
Explain how the lymphatic system helps the normal functioning of the circulatory system.
o Lymphatic system - A system of vessels sand nodes, separate from the circulatory system, which returns fluid, proteins, and cells to the blood. o The lymphatic system drains into large veins of the circulatory system at the base of the neck.
Explain how osmotic pressure and hydrostatic pressure regulate the exchange of fluid and solutes across capillary walls.
o Many blood proteins and blood and blood cells are too large to pass readily through the endothelium, and they remain in the capillaries. o The proteins create an osmotic pressure difference between the capillary interior and the interstitial fluid. o In places where the blood pressure is greater than the osmotic pressure difference, there is a net loss of fluid from the capillaries. o In contrast, where the osmotic pressure difference exceeds the blood pressure, there is a net movement of fluid from the tissues into the capillaries.
Explain how blood flow through capillary beds is regulated.
o One mechanism involves contraction of the smooth muscle in the wall of an arteriole, which reduces the vessel's diameter and decreases blood flow to the adjoining capillary beds. When the smooth muscle relaxes, the arterioles dilate, allowing blood to enter the capillaries. o The other mechanism for altering flow involves the action of precapillary sphincters, rings of smooth muscle located at the entrance to capillary beds. The signals that regulate blood flow include nerve impulses, hormones traveling throughout the bloodstream, and chemicals produced locally.
Describe the adaptive advantage of respiratory pigments in circulatory systems.
proteins that transport oxygen (and CO2), greatly increase the amount of oxygen that blood can carry
Compare the hearts of vertebrates with double circulation to those of vertebrates with a single circuit.
• 3 & 4 chambered hearts have DOUBLE circulation; Has an interior circuit within the heart--blood enters the heart, leaves the heart and gets oxygenated, enters the heart again, and then gets pumped out to the body. "Double circulation" allows oxygenated blood to be pumped back into the heart before going out to the body, it pumps blood with much more pressure and much more vigorously than "single circulation". • 2 chambered hearts like the fish have SINGLE circulation; Simply draw in deoxygenated blood in a single atrium, and pump it out through a ventricle. "Single circulation", as blood enters the heart, gets pumped through the gills and out to the body, Blood pressure is low for oxygenated blood leaving the gills
Describe respiratory adaptations of elite animals
•Deep-diving air breathers stockpile O2 and deplete it slowly •Weddell seals have a high blood to body volume ratio and can store oxygen in their muscles in myoglobin proteins •The extreme O2 consumption of the antelope-like pronghorn underlies its ability to run at high speed over long distances
Relate the structure of erythrocytes to their function.
•Do not have a nucleus •Biconcave disk •Contain hemoglobin for transporting oxygen (4 polypeptide chains with iron-containing heme groups in the middle which bind oxygen) •Live ~120 days and destroyed in spleen and liver •Erythrocytes allow for less viscous blood, higher concentrations of oxygen, and better diffusion of oxygen from the blood to the tissues
