3.3.1 Regional Circulations Flashcards

1
Q

Which organs require the largest amount of blood flow during rest?

A

Brain, Heart, Liver and Kidney

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2
Q

What is the equation for flow to an organ?

A
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3
Q

Why does resting blood flow differ between organs?

A

Resting blood flow to organs varies because of differences in vascular resistance between organs

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4
Q

When completely dilated which organ had the greatest increase in blood flow? Which has the least?

A

The skeletal muscle had the greatest increase, but heart is 5-fold.

Kidney had the lowest.

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5
Q

What organs rely mainly on local control of blood flow?

A

The heart and the brain.

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6
Q

What is oxygen uptake and what is the equation for it?

A
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7
Q

What can increase the oxygen uptake for an organ?

A

Opening of precapillary sphincter will increase the number of perfused capillaries.

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8
Q

What is the direct Fick Method and what is it’s equation?

A
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9
Q

Why is the heart able to consume so much more of the circulating oxygen than other tissues? How does this compare to the kidney?

A
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10
Q

What is autoregulation?

A
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11
Q

What allows for the brain and heart to maintain nearly constant flow? How does this compare to systemic organs?

A
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12
Q

What are the mechanisms for autoregulation?

A
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13
Q

What is the myogenic response and what is its pathway?

A
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14
Q

What is the metabolic hypothesis?

A

Vasodilator metabolites are produced by cells of many organs. Interstitial concentrations of these are determined by rate of formation and rate of removal.

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15
Q

What is the result of increased local metabolites? Will this change TPR significantly?

A
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16
Q

What is the role of adenosine as a vasodilator metabolite?

A

Adenosine levels rise wen ATP formation is impaired. Adenosine freely diffuses out of a cell and is a potent vasodilator.

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17
Q

How does potassium act as a vasodilator metabolite?

A

Potassium plays a major role in local regulation of blood flow in electrically organ such as the brain and heart. When the frequency of action potentials increases, the interstitial concentration of K+ rises. This local hyperkalemia causes hyerpolarization of arterioles within these organs, which decreases Ca++ influx to vascular smooth muscle, and causes relaxation.

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18
Q

How does lactic acid act as a vasodilator metabolite?

A

Increased interstitial levels of lactic acid and CO2 occur when O2 demand exceeds O2 availablility.

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19
Q

How can decreased ATP levels act as a vasodilator metabolite?

A

Decreased ATP (or increased ADP) leads to activation of KATP channels which increases K+ efflux, resulting in local hyperkalemia.

20
Q

What are this actions of all vasodilator metabolites?

A
21
Q

What is active hyperemia and what is its process?

A
22
Q

Again what is active hyperemia? What are the main vasodilators?

A
23
Q

How is exercise an example of active hyperemia?

A

It is an example in skeletal muscle. This will lead to formation of vasodilator metabolites and thus decreased vascular resistance

24
Q

Decribe the process of the baroreflex response during exercise

A
25
Q

What is reactive hyperemia?

A

This the phenomenon where blood flow is transiently increased following a brief period of ischemia. The classic example is when you cut off blood flow by a BP cuff.

26
Q

What is the process of reactive hyperemia?

A

Decreased stretched arterioles and accumulation of local vasodilators.

27
Q

What is the difference between ischemia/reperfusion vs hyperemia?

A
28
Q

How can the brain be an example of active hyperemia?

A
29
Q

What are the effect of changes in arterial PCO2 and PO2 on cerebral blood flow?

A

Increase in PCO2 will increase blood flow. Cerebral blood flow is highly sensitive to small changes in PCO2.

CBF changes very little which arterial PO2 levels change

30
Q

Since the brain doesn’t seem to react to changes in PO2 within normal ranges what could explain this?

A

The brain is able to extract sufficient blood as low as 50mmHg. Any lower and were screwed.

31
Q

Describe the sensitivity of the brain to changes in arterial CO2.

A
32
Q

What is the relationship between myocardial O2 consumption and blood flow?

A
33
Q

Describe the process of coronary blood flow during systole.

A
34
Q

Describe the process of coronary blood flow during diastole

A
35
Q

What are the determinants of myocardial O2 demand?

A

Inotropic state is the greatest determinant

36
Q

What is something to worry about with a patient having an MI?

A

Microvascular injury due to ischemia/reperfusion. This will create ROS which can damage the vessels. Can also lead to release of endothelin-1

37
Q

What is the process of pulmonary hypoxic arteriolar vasoconstriction?

A
38
Q

Describe gastrointestinal circulation

A
39
Q

How can cirrhosis lead to portal hypertension?

A
40
Q

What is the effect of portal hypertension in splanchnic veins?

A
41
Q
A

D

42
Q
A

C

43
Q
A

E

44
Q
A

D

45
Q
A

B