Vascular Control I&II Flashcards Preview

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Flashcards in Vascular Control I&II Deck (19)
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1
Q

Where in the vasculature is the resistance the highest? What does it determine?

A

Arterioles. It determines the after load.

2
Q

Where in the vasculature is the blood volume the highest?

A

In the peripheral venous compartment. It has the highest compliance too.

3
Q

What determines the preload?

A

The central venous compartment. Mostly its pressure

4
Q

What does the central venous compartment refer to?

A

The volume enclosed by the right atrium and the great veins in the thorax.

5
Q

What is venous return?

A

It is the rate at which blood returns to the thorax from the peripheral vascular beds and thus is the rate at which blood enters the central venous compartment.

6
Q

When there is a volume change in the central venous compartment what happens to the pressure? What happens to the heart?

A

It changes as well and has important effects on stroke volume and therefore cardiac output.

7
Q

If you were to stop someones heart what would be the mean systemic pressure? What does this come from?

A

7 mm Hg. This comes from the amount of fluid in the vasculature.

8
Q

What effect does increasing blood volume or venous tone have on the venous function curve?

A

It shifts the curve to the right and increases cardiac output.

9
Q

What effect does decreasing blood volume or venous tone have on the venous function curve?

A

It shifts the curve to the left and decreases cardiac output.

10
Q

What can shift a Frank-Starling curve left?

A

Sympathetic response.

11
Q

What can shift a Frank-Starling curve right?

A

Heart failure or heart disfunction.

12
Q

In a steady state what can you say about CO and venous return?

A

They are equal

13
Q

What happens to mean systemic filling pressure after increasing the volume? What happens to vascular function curve?

A

Increased volume shifts the curve to the right and increases mean systemic filling pressure. Vascular function curve shifts upward.

14
Q

What is the rate of flow when determining mean systemic filling pressure?

A

The flow is zero by definition. MSFP is thus the static equilibrium pressure that would be everywhere the same throughout the entire cardiovascular system when no blood is flowing.

15
Q

Does arteriolar tone affect the MSFP?

A

No it does not. Arterioles only hold 100cc of blood while veins hold 2500cc. Only volume affects MSFP.

16
Q

What effect does arteriolar constriction have on peripheral venous pressure, central venous pressure, and venous return?

A

It increases the after load and decreases peripheral venous pressure which decreases venous return due to a decreased pressure differential.

17
Q

What effect does arteriolar constriction have on peripheral venous pressure, central venous pressure, and venous return?

A

It decreases the after load and increases peripheral venous pressure which increases venous return due to an increased pressure differential.

18
Q

What is the only way to produce a different steady state match between venous return and cardiac output?

A

Change the cardiac function curve and/or the vascular function curve. A transfusion increases MAP and CO. Positive inotropic effect shifts the cardiac function curve and steady state CO increases. Increased HR or SV would also elevate cardiac function curve.

19
Q

What happens to veins and the heart with a sympathetic response?

A

The veins constrict and the heart becomes a stronger pump. These two together cause CO and VR to increase. VR increases because the vasoconstriction increases MSFP.