1. Which of the following mechanisms help blood fight gravity so that, for insta

Question

1. Which of the following mechanisms help blood fight gravity so that, for instance, it can return from blood vessels in your feet back into your heart? (there may be more than one answer)

Select one or more:

a. breathing allows the pressure in your chest to decrease and allow blood to flow up towards your heart

b. as you walk, the skeletal muscles in your legs contract and squeeze the veins; since veins have valves, blood flows up and doesn't backflow back down

c. the force of blood flowing out of the heart and into the arteries pushes all of the blood along, causing blood to return to the heart

d. precapillary sphincters open to allow blood to flow back towards the heart

2. The tricuspid and bicuspid/mitral valves prevent backflow of blood from the atria into the ventricles.

Select one:

True

False

3. The following sequence represents the correct order of blood flow through the heart:

inferior and superior vena cava --> right atrium --> right ventricle --> pulmonary artery --> lungs --> pulmonary vein --> left atrium --> left ventricle --> aorta

Select one:

True

False

4. The purpose of the coronary arteries is to bring oxygenated blood to the walls of the heart so that the muscles in the heart walls can contract.

Select one:

True

False

5. Vasodilation refers to the narrowing of blood vessels.

Select one:

True

False

Explanation / Answer

1. b. as you walk, the skeletal muscles in your legs contract and squeeze the veins; since veins have valves, blood flows up and doesn't backflow back down

2. True

3. True

4. True

5. False

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