Blood, blood flow and O2

Question 1

What is the function of veins?

Answer 1

carry deoxygenated blood back to the heart

Question 2

What is the structure of veins?

Answer 2

• wide lumen
• thinner elastic tissue layer
• thin smooth muscle layer
• carry blood at low pressure

Question 3

What is the function of arteries?

Answer 3

transport oxygenated blood back to the heart

Question 4

What is the structure of arteries?

Answer 4

• small lumen
• thick layer of smooth muscle
• thick elastic walls
• carry blood at high pressure

Question 5

What is the function of capillaries?

Answer 5

site of gaseous exchange

Question 6

What is the structure of capillaries?

Answer 6

• 1 cell thick walls (short diffusion pathway)
• large surface area (increasing O2 uptake)
• narrow diameter (slow blood flow down)

Question 7

What is the vascular shunt mechanism?

Answer 7

redistribution of blood to working muscles

Question 8

What happens to arterioles and precapillary sphincters at rest?

Answer 8

arterioles = to organs vasodilate increasing blood flow, whereas arterioles to muscles vasoconstrict

pre-capillary sphincters = to organs vasodilate opening capillary beds to cells, whereas constrict to muscle cell beds

Question 9

What happens to arterioles and precapillary sphincters during exercise?

Answer 9

arterioles = to organs vasoconstrict decreasing blood flow, whereas arterioles to organs vasoconstrict

pre-capillary sphincters = to organ beds vasoconstrict, whereas to muscle beds vasodilate

Question 10

What is the VCC and where is it located?

Answer 10

vasomotor control center

located in the medulla oblongata

Question 11

What does the VCC do?

Answer 11

alters the levels of stimulation sent to the arterioles and pre-capillary sphincters allowing the vascular shunt mechanism

Question 12

What information does the VCC receive and where from?

Answer 12

chemoreceptors = chemical changes such as CO2 and lactic acid

baroreceptors = pressure changes on arterial walls

Question 13

What responses does the VCC create?

Answer 13

increased sympathetic stimulation limiting blood flow to an area

decreased sympathetic stimulation increasing blood flow to an area

Question 14

How is blood pressure and blood flow increased during exercise by the VCC?

Answer 14

during exercise increases in CO2 and lactic acid are detected by chemoreceptors and baroreceptors detect increased stretch of vessel walls

receptors send an impulse to the VCC

this redistributes blood flow through sympathetic stimulation

increase in sympathetic stimulation results in the vascular shunt mechanism