Vessels of the systemic circulation Flashcards Preview

Physiology III > Vessels of the systemic circulation > Flashcards

Flashcards in Vessels of the systemic circulation Deck (14)
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1
Q

How are vessels categorized?

A

Based on size:
Microvessels
Macrovessels

2
Q

Why are arteries and arterioles considered to be the primary resistance vessels?

A

They have the most smooth muscle which contract or dilate to regulate blood flow

3
Q

What is the advantage to capillaries only being one cell thick?

A

Aide in exchange of diffuse substances

4
Q

How does the velocity of the blood increase as it returns to the heart?

A

The number of veins to capillaries is decreased (decrease CSA) which causes velocity to increase

5
Q

What two factors determine the CVP?

A

Venous return

Pumping ability of the right side of the heart

6
Q

How does blood make it back to the right side of the heart?

A

Venous blood only flows to the right atrium because of a favorable pressure gradient (venous pressure must be greater than right atrial pressure)

7
Q

What three factors cause and increase in venous return?

A

Increased blood volume
Increase large venous vessel tone
Dilation of arterioles (more blood moves to venous side)

8
Q

When can an increase in venous resistance occur?

A

Compression of vessels

Sharp angulations

9
Q

How can standing stationary for long periods of time cause edema in the lower extremities?

A

Since muscles are not moving and actively squeezing the blood back to the heart, the pressure in the veins builds up (up to 90mmHg) causing fluid collection and edema

10
Q

How does the valsalva maneuver effect venous return?

A

Generates a very large intrathoracic pressure that is transmitted to the vessels this increases resistance and generates a back pressure that will decrease venous return to the heart

11
Q

Why doesn’t forced expiration have equal effects as forced inspiration?

A

Forced inspiration causes sucking of blood back to the right atria from the negative intrathoracic pressure causing a large increase in blood return, forced expiration causes veins to collapse from positive intrathoracic pressure causing blood return to decrease but only by a little because we have valves that prevent the back flow of blood

12
Q

Why are patients at risk for vfib taught to cough rhythmically?

A

It is supposed to help maintain cerebral blood flow and consciousness

13
Q

What type of vessels determines the amount of blood flow for a given pressure?

A

The diameter of arterioles determines how much blood flow there will be for a given pressure

14
Q

Why do some people experience lightheadedness after a coughing fit?

A

Intrathoracic pressure is increased, narrowing or collapsing some of the vessels returning blood to the heart which causes resistance and generates a back pressure