HRR: peripheral circulation

Question 1

How does increased resistance impact flow?

Answer 1

It reduces it.

Question 2

What are myogenic mechanisms of altering smooth muscle tone?

Answer 2

A local regulation that can cause vessel diameter change; increased flow causes a stretch in the vessel wall, causing a stretch in the smooth muscle wall. The smooth muscle will send signals to the vessel to constrict. This increases resistance and decreases flow.

Question 3

What is the metabolic mechanism for regulating vascular tone?

Answer 3

Concentrations of molecules produced by metabolic activity can regulate blood vessel diameter; things like high CO2, lactate, and protons cause dilation.

Question 4

Is potassium a vasodilator or vasoconstrictor locally?

Answer 4

Vasodilator.

Question 5

Does adenosine act as a local vasodilator or vasoconstrictor?

Answer 5

Vasodilator.

Question 6

What are some examples of endothelial vasoconstrictors?

Answer 6

Endothelin-1 and thromboxane.

Question 7

What are some examples of endothelial vasodilators?

Answer 7

PGI2 and NO.

Question 8

What do endothelial vasoconstrictors activate to promote constriction?

Answer 8

PLC.

Question 9

What are extrinsic regulators of vessel size?

Answer 9

The SNS and PSNS.

Question 10

What is the effect of norepinephrine on vessels?

Answer 10

It activates PLC which causes vasoconstriction.

Question 11

How does acetylcholine lead to dilation?

Answer 11

NO release.

Question 12

What is the main region associated with central regulation?

Answer 12

The vasomotor region.

Question 13

What are major input regions for the vasomotor area?

Answer 13

Baroreceptors, chemoreceptors, visceral organs.

Question 14

Vasomotor inhibition leads to…

Answer 14

Vasodilation.

Question 15

Vasomotor activation leads to…

Answer 15

Vasoconstriction.

Question 16

Does a low blood pressure increase activate or inactivate VR?

Answer 16

Inactivate.

Question 17

Does lung inflation activate or inactivate VR?

Answer 17

Inactivate.

Question 18

How does epinephrine impact vessel diameter?

Answer 18

At low doses it will cause dilation, and at high doses it acts as a vasoconstrictor.

Question 19

How does vasopressin impact vessel diameter?

Answer 19

Vasoconstriction via PLC.

Question 20

How does Ang II impact vessel diameter?

Answer 20

Vasoconstriction via PLC.

Question 21

What is autoregulation?

Answer 21

Organs have intrinsic mechanisms to prevent massive flow changes when pressure changes occur. There will be an initial change, but an organ can use intrinsic mechanisms to return to steady state.

Question 22

What is active hyperemia?

Answer 22

Blood flow picks up due to dilation during exercise in order to maintain activity.

Question 23

Describe cutaneous circulation.

Answer 23

As the body warms, blood can be sent to the skin to dissipate the heat and cause sweating, both of which will lower core body temp.

Question 24

What is reactive hyperemia?

Answer 24

Releasing an occluded vessel will result in an overshoot of flow after restoration; the longer the occlusion, the higher the jump in flow.

Question 25

Which organs are under strong intrinsic control?

Answer 25

Brain, heart, skeletal muscle.

Question 26

Which organs are under strong extrinsic control?

Answer 26

Kidneys, splanchnic organs, skin.

Question 27

Describe the CNS ischemic response.

Answer 27

Decreased flow to the brain causes an increase in sympathetic activation, resulting in major vasoconstriction and cardiac acceleration. This preserves flow to the heart and brain at the expense of other systems.