Local control of Blood Flow (L)

Question 1

What is the equation for blood flow?

Answer 1

(Pa-Pv)/R

Question 2

Which type of control dominates blood flow in critical organs?

Answer 2

Intrinsic control

Question 3

What are the types of intrinsic control?

Answer 3

1. Metabolic control
2. Myogenic Response
3. Paracrine Control
4. Mechanical Compression

Question 4

Discuss Metabolic control

Answer 4

Increased Metabolism, Vasodilation, Increased blood flow

Question 5

How is metabolic control regulated?

Answer 5

1. As O2 consumption rises, vasodilators are released into ISF.
2. Arterioles dilate, increasing blood flow.
3. Increased blood flow washes out vasodilators.

Question 6

Define Active Hyperemia, Reactive Hyperemia and Autoregulation

Answer 6

1. Active Hyperemia: Increase in blood flow in response to increased metabolism.
2. Reactive Hyperemia: Increased blood flow following period when blood flow is stopped.
3. Autoregulation: The ability of an organ to maintain constant blood flow despite changes in pressure.

Question 7

What is Myogenic Response?

Answer 7

Stretches smooth muscle causing it to contract.

Question 8

How does myogenic response effect blood vessels?

Answer 8

1. Increase in transmural pressure stretches smooth muscle.
2. Opens stretch sensitive Ca channels.
3. Increased cytosolic Ca leads to contraction (vasoconstriction)

Question 9

Discuss Paracrine control

Answer 9

1. Histamine, Mast Cells, Vasodilation
2. NO, Endothelium, Vasodialtion
3. Prostacyclin, Endothelium, Vasodilation
4. Prostaglandin E2, Parenchymal cells, Vasodilation
5. Endothelin, Endothelium cells, Vasoconstriction
6. Thromboxane A2, Platelets, Vasoconstricition