Lecture 9: Venous Pressure and Vascular Function Curves

Question 1

What controls the filling of the heart?

Answer 1

Venous pressure, the heart will fill until the ventricular pressure = venous pressure

Question 2

What determines Venous Return?

Answer 2

Venous Pressure

Question 3

What is Venous Return?

Answer 3

The flow of blood into the ventricle from the veins

Question 4

What is the difference between a steady state and an equilibrium?

Answer 4

Steady state uses energy to stay relatively constant

Equilibrium does not use energy to remain constant

Question 5

When there is no blood flow, arterial pressure is _________ venous pressure and is solely determined by the ____________________________.

Answer 5

Arterial Pressure = Venous Pressure

Volume of blood and Compliance of the vessels

Question 6

What is the Mean Circulatory Pressure and what is its approximate value?

Answer 6

The average pressure across the circulation by volume

~7mmHg

Question 7

What changes the mean circulatory pressure?

Answer 7

MCP is independent of what the heart is doing
Increase in Venotone will increase MCP
Increase in Volume of blood will increase MCP

Question 8

The change in venous pressure is _____________________ to that of the arteries. Give an example:

Answer 8

Equal and opposite

If arterial volume goes up, then venous volume goes down by the same amount

Question 9

Why does the same volume of blood create a higher pressure in the arteries than the veins?

Answer 9

Arteries are less compliant than veins

Question 10

What generates the flow of blood?

Answer 10

Pumping of the heart –> ↑ volume and ↑ arterial pressure –> ↓ venous volume and ↓ pressure => pressure difference which causes flow

Question 11

At steady state the flow across the heart is ___________ the flow across the capillaries

Answer 11

equal to

Question 12

With flow, the arterial pressure is ____________ MCP and the venous pressure is _____________ MCP.

Answer 12

Increased above MCP

Decreased below MCP

Question 13

Increasing the CO or Total Peripheral Resistance ___________ Arterial Pressure and ___________ Venous Pressure

Answer 13

Increases Arterial Pressure

Decreases Venous Pressure

Question 14

What is a vascular function curve?

Answer 14

A plot of the relationship between Cardiac Output and Central Venous Pressure

Question 15

Where does the Vascular f(x) curve intersect the y-axis?

Answer 15

The MCP ~7mmHg

Question 16

What happens when Venous pressure drops below intrathoracic pressure?

Answer 16

Veins collapse and there is no filling of the heart

Question 17

How does an increase in blood volume affect the Vascular f(x) curve?

Answer 17

↑ MCP and ↑ the venous pressure at any CO, curve shifts right

Question 18

How does a decrease in blood volume affect the Vascular f(x) curve?

Answer 18

↓ MCP and ↓ Venous pressure at any CO, curve shifts left

Question 19

How does an increase in venotone affect the vascular f(x) curve?

Answer 19

Has similar effects as increase blood volume, ↑ MCP and ↑ the venous pressure at any CO, curve shifts right

Question 20

How does vasoconstriction (increase in total peripheral resistance) affect the vascular f(x) curve?

Answer 20

Decreases the slope of the line so that venous pressure is less for any CO

Question 21

What increases Venous Pressure?

Answer 21

Increase in Blood Volume

Increase in Venoconstriction

Question 22

What decreases Venous Pressure?

Answer 22

Increase in Vasoconstriction
Increase in Total Peripheral Resistance
Increase in CO