Circulatory System

Question 1

function of circulatory system (2)

Answer 1

• rapidly transport substances throughout the body

- hormones, nutrients, immune cells, gases, waste

Question 2

arteries

Answer 2

• blood vessels that carry blood away from the heart

Question 3

veins

Answer 3

• blood vessels that carry blood toward the heart

Question 4

general circulation patterns (2)

Answer 4

• arteries branch into network of smaller arterioles leading to the capillaries, where the exchange of nutrients, gases, and wastes take place
• blood drains from the capillaries into venules, then passes through a series of larger and larger venules, then into veins which carry the blood back to the heart

Question 5

vasoconstriction (2)

Answer 5

• contraction of smooth muscle in walls of blood vessels

- decreases blood flow through vessel

Question 6

vasodilation (2)

Answer 6

• relaxation of smooth muscle

- increases blood flow through the vessel

Question 7

what does vasoconstriction and vasodilation allow for

Answer 7

• regulation of distribution of blood flow throughout the body, particularly in arterioles and small arteries

Question 8

how is blood flow into the capillary beds controlled (3)

Answer 8

• precapillary sphincters: rings of smooth muscle that act as valves
• when they contract, they constrict blood vessels, reducing the flow of blood through that vessel
• when they relax, the vessel dilates, increasing the blood flow through that vessel

Question 9

branchial circulation

Answer 9

• blood flow to and from the gills

Question 10

systemic circulation

Answer 10

• blood flow through all the regions of the body except the gas exchange surfaces

Question 11

single circulation

Answer 11

• when blood passes only once through the heart during a complete circuit

Question 12

pulmonary circulation

Answer 12

• blood flow to and from the lungs

Question 13

double circulation

Answer 13

• blood is passed twice through the heart during one complete circuit

Question 14

hepatic portal system (3)

Answer 14

• all vertebrates
• delivers blood directly from lining of digestive system to the liver
• metabolize possible toxins from digestive tract and for storage/regulation of glucose

Question 15

branchial circulation

Answer 15

heart -> ventral aorta -> afferent branchial artery of aortic arches -> capillaries -> efferent branchial artery -> dorsal aorta

Question 16

actinopterygii

Answer 16

• aa III, IV, V, VI supply gills with blood

- sinus venosus, atrium, ventricle, bulbus arteriosus

Question 17

basic structure of the heart

Answer 17

• 3-4 distinct chambers arranged in series

- chambers are separated with one-way valves

Question 18

myogenic heart

Answer 18

• cardiac muscles can stimulate themselves to contract

Question 19

sinus venosus (2)

Answer 19

• chamber with the fastest rhythm and sets rhythm for rest of heart
• cardiac muscle cells are electrically coupled

Question 20

conus arteriosus (3)

Answer 20

• contractile heart chamber composed of cardiac muscle
• once ventricle has contracted fully and begins to relax, the conus arteriosus contracts to to prolong period of blood flow
• contraction also closes conal valves, preventing backflow of blood as the ventricle relaxes

Question 21

bulbus arteriosus (4)

Answer 21

• heart chamber composed of smooth muscles; it does not contract, but is very stretchy
• when the ventricle contracts, this stretches and slowly recoils, gently squeezing blood into the ventral aorta
• prolongs period of blood flow, minimizes pressure surges
• bulbal valve prevents backflow of blood as ventricle relaxes

Question 22

cardiac shunt

Answer 22

• crocodilians can control whether they send blood in right ventricle to the lungs or to systemic circulation

Question 23

when do crocodilians use the cardiac shunt/when do organisms favour mixing of blood (3)

Answer 23

• used when diving or during feeding
• diving: deoxygenated blood still has some O2 to help with cellular respiration
• eating: deoxygenated blood delivered to the stomach capillaries to increase acidity in stomach and aid in chemical digestion

Question 24

why do birds and mammals have no mixing of deoxygenated and oxygenated blood

Answer 24

• both need high metabolic rate to maintain endothermy, which requires efficient circulation and delivery of O2 to tissues

Question 25

what would happen if right ventricle was as strong as the left ventricle (2)

Answer 25

• blood pressure in pulmonary arteries would be too high and fluid would be forced out of the capillaries into the alveoli or air capillaries
• pulmonary edema would results; essentially drowning

Question 26

why is left ventricle so strong

Answer 26

• must pump blood to the entire systemic circuit, so it must generate a for large enough to overcome large resistance to blood flow of many systemic capillary beds of the body

Question 27

mammal diving adaptations: vasocontriction (3)

Answer 27

• large amounts of vasoconstriction to areas that are not essential during diving
• helps to maximize available O2 use during long dives
• increases blood pressure as a result, but can be counteracted with slowing of heart rate

Question 28

mammal diving adaptations: aortic bulb

Answer 28

• elastic, non-pumping enlargement of aorta helps to maintain constant blood flow while diving