Vascular capacity

Question 1

What is the vascular capacity?

Answer 1

The volume of blood that can fit into blood vessels

Question 2

What 2 things regulate vascular capacity?

Answer 2

Cardiac output and vascular diameter

Question 3

What is cardiac output?

Answer 3

The volume of blood that the heart pumps per unit time. Determined by heart rate x stroke volume

Question 4

What is the stroke volume?

Answer 4

The volume of blood that the heart pumps with each beat

Question 5

What regulates stroke volume?

Answer 5

Venous return (preload, filling of right atrium)
Arterial pressure (afterload)
Contractility (rate and strength of contractions)

Question 6

How is stroke volume controlled intrinsically?

Answer 6

Venous return (ΔEDV) and arterial pressure

Question 7

How is stroke volume controlled extrinsically?

Answer 7

Contractility has regulated by the nervous system and endocrine system

Question 8

What is the EDV (end diastolic volume)?

Answer 8

Maximum amount of blood in the ventricles

Question 9

What happens to the stroke volume if blood volume is increased? What is the series of events that leads to that?

Answer 9

Increased blood volume means increased EDV, which increases stretching of the ventricles, which increases the strength of contraction and increases SV

Question 10

Does the end diastolic volume stay constant?

Answer 10

Changes with the amount of blood returning to the heart

Question 11

What is the Frank Starling Law of the Heart?

Answer 11

The heart pumps out all the blood that enters the ventricles

Question 12

What happens to the ventricle muscles when the end diastolic volume increases?

Answer 12

The muscles get stretched and contract stronger in response, which increases the stroke volume

Question 13

How does the sympathetic nervous system affect the stroke volume?

Answer 13

Causes it to increase, which causes more blood to be pumped around the body and circulate stress hormones

Question 14

What is the mean arterial pressure?

Answer 14

The pressure gradient across the circulatory system

Question 15

What is the total peripheral resistance?

Answer 15

The sum of the resistance of all blood vessels in the circulatory system

Question 16

Between the cardiac output, mean arterial pressure, and total peripheral resistance, which one does stays constant?

Answer 16

Mean arterial pressure. Bulk flow of the entire system depends on the pressure gradient

Question 17

How is total peripheral resistance changed?

Answer 17

Vasoconstriction and vasodilation

Question 18

How does the body redirect blood flow away from certain organs?

Answer 18

Arteriolar-venular shunts

Question 19

Which blood vessels determine which organs get access to blood flow?

Answer 19

Arterioles

Question 20

How is a capillary bed closed off or opened?

Answer 20

Sphincters composed of rings of smooth muscle cells. They contract to close off a capillary bed like a valve

Question 21

Why would blood be shunted away from an area?

Answer 21

Low metabolic needs

Question 22

What happens in the capillary beds of organs with high metabolic needs?

Answer 22

Pre-capillary sphincters relax and the arterioles dilate, which decreases the resistance and increases the amount of blood received by that region

Question 23

What are baroreceptors?

Answer 23

Pressure sensors found in the arterial system that sense artery stretching due to increased cardiac output

Question 24

What do baroreceptors do when they sense an increase in artery pressure?

Answer 24

Send a signal to the medulla oblongata which causes a reflex reduction of the cardiac output and peripheral vascular resistance to maintain the MAP