Lecture 11: Controlling Regional Blood Flows

Question 1

How is Cardiac output “DISTRIBUTED” to all organs?

Answer 1

• Continual branching of arterial
  network.
• Divides blood flow among the
  regional (organ) circulations.

Question 2

What is the Distribution of cardiac output during exercise?

Answer 2

• Increase in blood flows to:
  – Muscle
  – Heart
  – Skin
• Decrease in blood flows to:
  – GI tract
  – Kidneys
• Constant blood flow to:
  – Brain

Question 3

Which of the following events is NOT associated with
isovolumetric contraction of the ventricles?
A. Ventricular pressure increases rapidly
B. A “T wave” can be observed using ECG
C. The ventricle is depolarized
D. Ventricular volume stays relatively constant

Answer 3

B

Question 4

How is MAP controlled during exercise?

Answer 4

Systemic Circulation:
* Increased cardiac output (CO)
* Constant mean arterial pressure
(MAP)
* Decreased total peripheral
resistance (TPR)
- Resistance varies eg. muscles have less resistance as they have a greater need for the blood compared to the kidneys where resistance would increase.

Question 5

If your cardiac output fell temporarily, which of the
following would occur to maintain mean arterial blood
pressure?
A. Decreased heart rate
B. Increased body temperature
C. Decreased stroke volume
D. Increased total peripheral resistance

Answer 5

D

Question 6

Define vasoconstriction vs vasodilation

Answer 6

Vasoconstriction is the smooth muscle in blood vessels contracting which decreases the internal diameter, increases resistance and decreases blood flow

Vasodilation is the smooth muscle in blood vessels relaxing which increases the internal diameter, decreasing resistance and increases blood flow

Question 7

The luminal space of a blood vessel changes by a factor of 2. What happens to the resistance?

Answer 7

Resistance changes by a factor of 16
- Luminal space halves, resistance increases by a factor of 16
- Luminal space doubles, resistance decreases by a factor of 16