W4-L5: Exercise and blood pressure

Question 1

What happens to blood flow during exercise

Answer 1

During exercise, local arterioles of active muscles dilate, while vessels to tissues that can temporarily compromise their blood supply constrict

Question 2

What Two factors contribute to reduced blood flow to non-active tissues?

Answer 2

1. Increased sympathetic nervous system outflow
2. Local chemicals that directly stimulate vasoconstriction or enhance effects of other vasoconstrictors

Question 3

Factors Within Active Muscle

Answer 3

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Question 4

What do The opening of dormant capillaries in exercise cause?

Answer 4

The opening of dormant capillaries in exercise:

• Increases total muscle blood flow
• Delivers a large blood volume with only a minimal increase in blood flow velocity
• Increases effective surface for gas and nutrient exchange

Question 5

Vasodilation occurs from local factors related to tissue metabolism that act directly on smooth muscle bands of small arterioles and precapillary sphincters
What casues this?

Answer 5

• Examples include decreased tissue oxygen and local increases in blood flow, temperature, carbon dioxide, acidity, adenosine, mg and k+ ions, and nitric oxide production by endothelial cells lining the blood vessels
• Venous system may also increase local blood flow by “assessing” increases in the metabolic needs of active muscle and releasing vasodilatory factors

Question 6

How does Nitric Oxide dilate blood vessels?

Answer 6

• Nitric oxide dilates blood vessels by activating guanylate cyclase in smooth muscle cells, increasing cGMP levels, and leading to smooth muscle relaxation and vessel dilation.
• Nitric oxide serves as a signal molecule that dilates blood vessels and decreases vascular resistance
• Stimuli from diverse signal chemicals and sheering stress and vessel stretch from increased blood flow through the vessel lumen provoke NO synthesis and released by vascular endothelium
• In CHD, vascular endothelium produces less NO

Question 7

Integrative Response During Physical Activity

Answer 7

Integrative Response During Physical Activity

• Initiation: Neural command center initiates cardiovascular changes pre- and during movement.
• Heart Rate and Contractility: Increase due to feed-forward input, reducing parasympathetic activity.
• Blood Flow: Adjusts predictably with exercise intensity.
• Vessel Modulation: Dilates/constricts to optimize blood flow and maintain blood pressure.
• Local Metabolic Effects: Directly dilate vessels in active muscle, reducing peripheral resistance.
• Vasoconstriction: Occurs in inactive tissues to ensure adequate blood flow to both active muscles and inactive areas.

Question 8

Why is a Heart transplant bad for exercise?

Answer 8

Getting a heart transplant negatively affects exercise ability because the transplanted heart lacks direct neural connections, resulting in a slower and less efficient response to exercise demands, including slower heart rate adjustments and reduced peak exercise capacity.

Question 9

Exercise HR before/ after transplant

Answer 9

Question 10

Answer 10

Resistance to blood flow is primarily influenced by three factors: blood viscosity, vessel length, and vessel radius.

Viscosity and length of the vessel directly affect resistance—higher viscosity and longer vessel length increase resistance.

Radius of the vessel has a profound effect due to the inverse relationship, where even a small decrease in radius results in a substantial increase in resistance, and an increase in radius significantly reduces resistance.