Topic 11: Cardiovascular System - Blood Circulation - Control

Question 1

What are the factors that control vasoconstriction/dilation of arteriolar radius? (4)

Answer 1

intrinsic regulation
- myogenic regulation
- metabolic regulation

Extrinsic regulation
- neural (SNS)
- hormonal

Question 2

What does intrinsic regulation of arteriolar radius allow for?

Answer 2

organ to control its own blood flow

Question 3

What occurs in myogenic regulation?

Answer 3

• intrinsic
• when smooth muscle is stretched, it contracts
• if it increases systemic bp, arterioles contract

Question 4

Give examples of myogenic regulation in terms of feet and brain. (4)

Answer 4

1) standing
- high arterial bp in feet (gravity) so arterioles constrict
- decreased flow into capillaries

• but low arterial bp in brain (gravity)
• arterioles dilate and increased flow into capillaries

Question 5

What occurs in metabolic regulation? (5)

Answer 5

• intrinsic
  1) blood levels of decreased oxygen and increased CO2, decreased pH (increases metabolism in organ)
• endothelial cells and hemoglobin release nitric oxide for vasodilation, so increased blood flow to organ

2) if increased O2 and pH but decreased CO2 (low metabolism), endothelial cells release endothelinss
- causes vasoconstriction
- decreased blood flow to organ

Question 6

What does both myogenic and metabolic regulation allow for? (2)

Answer 6

• maintenance of blood gases and pH levels
• very important in heart, skeletal muscle, and brain

Question 7

What systems control extrinsic regulation of arteriolar radius?

Answer 7

• NS and Endocrine

Question 8

What is neural regulation of arteriolar radius? (4)

Answer 8

• SNS
• arteriolar vasoconstriction except in brain (intrinsic regulation only)
• vasodilation due to decreased SNS signals
• venoconstriction (vein contraction)

Question 9

What is the function of PSNS in neural regulation of arteriolar radius?

Answer 9

only important PSNS effect is dilation of arterioles of penis/clitoris

Question 10

What hormones are responsible for hormonal regulation of arteriolar radius? (4)

Answer 10

• epinephrine
• angiotensin II
• ADH
• histamine

Question 11

What is the function of epinephrine for vasocontriction? (2)

Answer 11

• vasoconstriction of skin, viscera
• reinforces SNS

Question 12

What is the function of epinephrine for vasodilation? (2)

Answer 12

• heart, skeletal muscle, liver
• opposes SNS

Question 13

What is the function of angiotensin II and ADH for arteriolar radius?

Answer 13

• vasoconstriction

Question 14

What is the function of histamine in arteriolar radius?

Answer 14

vasodilation