CV system structure- LOs

Question 1

describe 2 primary roles of the CV system

Answer 1

1. distribution of essential substances to the tissues (dissolved gases, molecules for nutrition, growth, repair)
2. removal of by products of metabolism

Question 2

describe 3 secondary roles of the CV system

Answer 2

1. circulation of hormones and neurotransmitters that allow for chemical signaling among cells (humoral communication)
2. heat dissipation: by transfer from core to body surface
3. mediation of defense responses against invading microorganisms (immunity!)

Question 3

what are the 2 pumps of the heart? how are they arranged?

Answer 3

1. right heart: propels oxygen-poor blood through the lungs (pulmonary circulation)
2. left heart: propels oxygen-rich blood to all other tissues (systemic/peripheral circulation)
   these pumps are arranged end to end or in series

Question 4

describe the position of the AV valves during the cardiac cycle

Answer 4

open when ventricles relax (filling phase) to allow blood to drop from atria into ventricle
close when ventricles contract (ejection phase) to prevent backflow/regurgitation of blood into atria

Question 5

describe the position of the semilunar valves during the cardiac cycle

Answer 5

open when ventricles contract (ejection phase) to allow blood to exit ventricle
close when ventricles relax (filling phase) to prevent backflow (regurgitation) of blood into ventricle

Question 6

describe the path of blood flow through the heart (5)

Answer 6

1. oxygen-poor blood enters the right atrium from cranial and caudal vena cavae and coronary sinus
2. blood crosses the tricuspid valves to enter the right ventricle, which pumps it across the pulmonary valve and into pulmonary circulation through the pulmonary artery
3. in the pulmonary capillaries, gas exchange occurs
4. oxygen-rich blood returns to the left atrium through the pulmonary veins
5. blood crosses the mitral valve to enter the left ventricle, which pumps it across the aortic valve and into systemic and coronary circulations via the aorta

Question 7

what are the 5 components and functions of the cardiovascular tree?

Answer 7

1. arteries: distribute blood from heart under high pressure
2. arterioles/small arteries: smooth down the arterial pulsations and regulate blood flow into capillaries
3. capillaries: exchange gases between blood and systemic tissues
4. venules: collect blood from capillaries
5. veins: deliver blood back to heart and serve as major reservoir for blood (have a blood pool, will squeeze back to heart when blood pressure drops to push back to circulation

Question 8

how is continuous, low pressure flow to capillaries made possible? (2)

Answer 8

1. aorta and large arteries are compliant and elastic, allow for distension to absorb energy when ventricle contracts and recoil to maintain propulsion when ventricle is not contracting
2. small arteries and arterioles provide resistance to blood flow, causing a pressure-lowering effect

Question 9

what happens to vessel lumen, wall compliance, and elasticity as you move down the vascular tree?

Answer 9

1. vessel lumen gets smaller as smooth muscle increases
2. vessel wall compliance and elasticity decreases as elastic fibers and collagen decrease