Blood Flow And Pressure Control - Phys I

Question 1

Two mechanisms for blood flow control in local tissues exist. What are they?

Answer 1

Acute control - vasodilation and constriction due to SNS control (constriction)

Long-term control - increase in size/no. of vessels

Question 2

Increased metabolism in tissues results in decreased oxygen availability. This mechanism produces ______.

Answer 2

Vasodilator

• adenosine (from use of ATP)
• carbon dioxide
• ADPs/AMPs
• Histamine
• K+
• H+
• Nitric oxide (NO)

Question 3

Explain the mechanism by which carotid massage works.

Answer 3

• Carotid baroreceptors are stimulated by pressure, by which the AP enters the medulla.
• Medullary centers are inhibited (vasoconstrictor center) and stimulated (vagal PNS centers).
• Both mechanisms decrease HR, have negative inotropic effects, and venodilate

Question 4

In addition to production of vasodilators, what other mechanism of acute blood flow control is stimulated by decreased [oxygen]?

Answer 4

Nutrient lack theory

- without adequate oxygenation, oxidative phosphorylation cannot occur, and therefore, no vasoconstriction is possible

Question 5

This is the cyclical opening/closing of precapillary sphincters.

Answer 5

Vasomotion