Heart Lecture 9: Coupling of the Heart and the Peripheral Vasculature

Question 1

What happens to the amount of blood in the central venous pool when you take a deep breath?

Answer 1

Increases the blood to the right atrium

Question 2

As central venous pressure increases, cardiac output __________

Answer 2

decreases (at 7mmHg, cardiac output is zero)

Question 3

As CVP decreases, cardiac output ______________

Answer 3

increases

Question 4

What is the mean circulatory pressure (Pmc)?

Answer 4

When central venous pressure is the SAME as peripheral venous pressure

Question 5

What two factors influence Pmc?

Answer 5

1) volume

2) venous tone

Question 6

What three things increase when venous return increases?

Answer 6

1) cardiac output
2) stroke volume
3) end diastolic volume

Question 7

How does venous return increase or decrease?

Answer 7

the pressure gradient is altered between peripheral and central venous pressure

Question 8

What four factors can increase the peripheral venous pressure?

Answer 8

1) increased sympathetic venoconstriction
2) increased blood volume
3) increased skeletal leg muscle pumping activity
4) cardiac contraction

Question 9

What two factors can decrease central venous pressure?

Answer 9

1) increased respiratory pump activity

2) cardiac suction

Question 10

Venoconstriction increases venous return by __________ compliance of veins which makes for a stiffer pipe

Answer 10

decreasing

Question 11

Sympathetic nerve activity has what effect on venous blood flow?

Answer 11

constricts it thereby increasing venous return

Question 12

What is normal CVP and cardiac output?

Answer 12

CVP: 2mmHg

Cardiac output: 5L/min

Question 13

What are two scenarios that can lead to a decrease in central venous pressure?

Answer 13

1) cardiac output increases (takes more blood from the pool)

2) hemorrhaging (bleeding internally)

Question 14

How does cardiac output respond to a sudden increase in CVP?

Answer 14

it acutely increases but that then causes a reduction in CVP

Question 15

What does a transfusion graph look like compared to a control on the CVP vs. cardiac output graph?

Answer 15

It parallels the control line but the fullness of the system is increased (more volume in circulation) thereby increasing CVP

Question 16

What does a hemorrhage graph look like compared to a control on the CVP vs cardiac output graph?

Answer 16

It parallels the control line but the fullness of the system is DECREASED

Question 17

Does a hemorrhage or transfusion change the mean systemic circulatory pressure?

Answer 17

YES

hemorrhage –> decreases Pmc
transfusion –> increases Pmc

Question 18

What are the only two factors that influence venous function?

Answer 18

1) Blood volume

2) Venous tone

Question 19

What do an increase in blood volume and an increase in venous tone do to venous return?

Answer 19

INCREASES it

Question 20

What happens to blood volume and venous tone when venous return decreases?

Answer 20

they both decrease

Question 21

What factors influence the level of cardiac function?

Answer 21

1) sympathetic stimulation
2) inotropic (contractility) drugs
3) heart failure (depresses cardiac function curve)

Question 22

How does CVP respond to a sharp increase in cardiac output (as a result of sympathetic stimulation)?

Answer 22

Acutely decreases since that increase in cardiac output pulls more blood out of the central venous pool

Question 23

How does heart failure affect the cardiac function curve?

Answer 23

shifts it down and to the right (decreases cardiac output and increases CVP)

Question 24

What happens to vein diameter in response to hemorrhage?

Answer 24

DECREASES (venoconstricts) to get more blood back to the central venous pool faster to help save cardiac output a little bit (that also increases CVP)

Question 25

What sector of the autonomic nervous system kicks in during times of hemorrhage?

Answer 25

SYMPATHETIC –> increases contractility of the heart helping to save cardiac output a bit

Question 26

What is responsible for maintaining the pressure gradient between peripheral and central venous pools in the face of gravitation forces?

Answer 26

Venous valves

Question 27

What generates venous pressure?

Answer 27

cardiac contraction