Mcq_mini3 Local Control Of Blood Flow

1. During vigorous exercise, skeletal muscle blood flow increases greatly. What is the circulatory adjustment most responsible for this change?

Increased beta-adrenergic receptor stimulation in skeletal muscle blood vessels.

Increased local vasodilation in skeletal muscles.

Increased cardiac stroke volume.

Increased cardiac parasympathetic stimulation.

During vigorous exercise, the demand for oxygen and nutrients by the skeletal muscles increases. To meet this demand, the circulatory system undergoes adjustments to increase blood flow to the muscles. The most responsible circulatory adjustment for this change is increased local vasodilation in skeletal muscles. Vasodilation occurs when the smooth muscles in the blood vessels relax, allowing the vessels to widen and increase blood flow. This local vasodilation in the skeletal muscles helps to deliver more oxygen and nutrients to the working muscles, enabling them to continue functioning efficiently during exercise.

Explanation

During vigorous exercise, the demand for oxygen and nutrients by the skeletal muscles increases. To meet this demand, the circulatory system undergoes adjustments to increase blood flow to the muscles. The most responsible circulatory adjustment for this change is increased local vasodilation in skeletal muscles. Vasodilation occurs when the smooth muscles in the blood vessels relax, allowing the vessels to widen and increase blood flow. This local vasodilation in the skeletal muscles helps to deliver more oxygen and nutrients to the working muscles, enabling them to continue functioning efficiently during exercise.

2. Which of the following will REDUCE vascular smooth muscle tone (resting tension)?

Stimulating nitric oxide (NO) production

Stimulating the intrinsic myogenic mechanism of blood vessels

Stimulating alpha-1 receptors

Stimulating beta-2 receptors

Stimulating nitric oxide (NO) production will reduce vascular smooth muscle tone (resting tension). Nitric oxide is a potent vasodilator that relaxes the smooth muscle in blood vessels, leading to vasodilation and a decrease in vascular tone. This allows for increased blood flow and decreased resistance in the blood vessels.

Explanation

Stimulating nitric oxide (NO) production will reduce vascular smooth muscle tone (resting tension). Nitric oxide is a potent vasodilator that relaxes the smooth muscle in blood vessels, leading to vasodilation and a decrease in vascular tone. This allows for increased blood flow and decreased resistance in the blood vessels.

3. What happens to local vascular resistance following an increase in adenosine levels in the interstitial fluid surrounding the arterioles in skeletal muscle?

Does not change

Decreases

Increases

RESISTANCE and Diameter are inversely related

Explanation

RESISTANCE and Diameter are inversely related

4. If you occlude blood flow to a skeletal muscle for 1 minute, what changes will occur immediately following the removaI of the occlusion?

A 15-30 second period during which flow slowly increases to the normal value

A 15-30 second period during which flow is markedly higher than prior to occlusion

A rapid (less than 2 seconds) return to normal flow

This is reactive Hyperemia

Explanation

This is reactive Hyperemia

5. While jogging on a treadmill, predict how the increase in activity will affect the tone of the arterioles in the active skeletal muscles and the volume of blood flow through the active skeletal muscles (as compared to rest).

tone of the arterioles in the active skeletal muscles

volume of blood flow through the active skeletal muscles

Increase increase

Increase decrease

Decrease decrease

Decrease increase

No change increase

No change decrease

capillaries have no change in tone, ARTRIOLES do

Explanation

capillaries have no change in tone, ARTRIOLES do

6. Local control of the circulation prevails over neural control in which of the following organs?

Brain

Skin

GI tract

Skeletal muscle

also kidney

Explanation

also kidney

7. A hypothetical drug given intravenously caused a decrease in mean arterial pressure and at the same time a decrease in heart rate. Which of the following could explain the actions of this drug?

Beta-1 and Beta-2 receptor agonist

Alpha-1 receptor agonist

Inhibitor of parasympathetic effects in heart muscle

Stimulator of histamine release

Beta-l and Alpha-l antagonist

The drug is likely a Beta-1 and Alpha-1 antagonist, as it causes a decrease in both mean arterial pressure and heart rate. By blocking the Beta-1 receptors, the drug reduces the heart's contractility and therefore decreases heart rate. By blocking the Alpha-1 receptors, the drug causes vasodilation, which leads to a decrease in mean arterial pressure.

Explanation

The drug is likely a Beta-1 and Alpha-1 antagonist, as it causes a decrease in both mean arterial pressure and heart rate. By blocking the Beta-1 receptors, the drug reduces the heart's contractility and therefore decreases heart rate. By blocking the Alpha-1 receptors, the drug causes vasodilation, which leads to a decrease in mean arterial pressure.