SFP: hemodynamics

Question 1

For flow to happen there has to be…

Answer 1

A pressure gradient

Question 2

What is cardiac output?

Answer 2

Sum of all tissue flow; determined by ventricles

Question 3

What regulates blood flow to each organ?

Answer 3

Tissue demand; blood can be shunted away from tissues that don’t need it

Question 4

If pressure falls acutely, which reflexes are activated?

Answer 4

Increased HR, contractility, venous return, and constriction of arterioles

Question 5

What is the long term control of MAP?

Answer 5

The kidneys

Question 6

How do lungs get more than 00% of CO?

Answer 6

They get 100% from the right side for pulmonary circulation, and 2% from bronchioles on the left side

Question 7

Where is pressure lowest in the systemic circuit?

Answer 7

Right atrium

Question 8

What is the windkessel effect?

Answer 8

Elastic arteries receive a bonus during ventricle ejection that slowly releases forward during ventricle diastole. This allows for continuous flow as opposed to pulsatility

Question 9

How does having a stiff artery impact the windkessel effect?

Answer 9

The afterload to the ventricle increases, and the ability to stretch and receive the bolt for continuous flow is reduced. The risk for dissection is great.

Question 10

Are veins or arteries more compliant?

Answer 10

Veins

Question 11

Describe how a vessel can locally override a systemic sympathetic signal.

Answer 11

In a systemic sympathetic signal, areas of constricted blood flow can produce products like adenosine, lactate and protons, pCO2, and potassium. These can act as local vasodilators to dilate a specific vessel.

Question 12

What is the biggest factor that controls resistance?

Answer 12

Radius

Question 13

What are myogenic controls of flow?

Answer 13

Intrinsic property of vascular smooth muscle. They contort to oppose stretch and relax to oppose dilation. This allows them to keep the flow constant.

Question 14

What are endothelial controls of flow?

Answer 14

Things like NO and endothelin

Question 15

What are metabolic controls of flow?

Answer 15

Metabolic rates and products of local tissues can locally override a systemic signal and alter flow.

Question 16

Vasopressin causes ___

Answer 16

Vasoconstriction

Question 17

What is filtration?

Answer 17

Net fluid out of the capillary (positive)

Question 18

What is reabsorption?

Answer 18

Net fluid movement into the capillary (negative)

Question 19

What are the 4 starling forces?

Answer 19

Capillary hydrostatic pressure, interstitial fluid hydrostatic pressure, plasma colloid osmotic pressure, interstitial fluid colloid osmotic pressure

Question 20

Which forces result in fluid leaving the capillary?

Answer 20

Hydrostatic pressure pushes fluid out and interstitial osmotic pressure pulls fluid out

Question 21

Which forces result in fluid entering the capillary?

Answer 21

Plasma colloid osmotic pressure and interstitial fluid hydrostatic pressure

Question 22

What is a main cause of edema in the cardiovascular system?

Answer 22

Increased venous pressure

Question 23

What pathology is associated with expansion of a blood vessel?

Answer 23

Aneurysm

Question 24

What pathology is associated with coarctation?

Answer 24

Stenosis

Question 25

If vessel cross-sectional area increases what has to happen to velocity?

Answer 25

It decreases

Question 26

What happens to potential energy when a vessel suddenly constricts?

Answer 26

Velocity increases, which increases kinetic energy and causes potential energy to lower. This forms a lower pressure inside the vessel that can cause collapse.

Question 27

What does turbulent flow do to energy?

Answer 27

Causes energy loss and more pressure has to be generated

Question 28

Describe how a dilated vessel can lead to aneurysm.

Answer 28

A dilated vessel can slightly lower kinetic energy, causing a small bump in potential energy. This causes an increase in pressure which combined with a thinning of the wall and increase in wall stress from dilation can cause aneurysm.