Question

Which of the following do NOT affect venous return?

Select one:

a. breathing/inspiration

b. epinephrine/norepinephrine

c. skeletal muscle contraction

d. all of the above affect venous return

Answer 1

Answer:

The correct option is “d. all of the above affect venous return”.

Venus return is the activity associated with the flow of blood back to the heart.

There are many factors or conditions which affect venous return:

• Breathing/inspiration: Breathing/inspiration increases the venous return. Inspiration make the pressure in thoracic cavity negative which induces increased venous return because of more blood flow in right atrium.
• Epinephrine/norepinephrine: Epinephrine increases venous return due to increase in the mean circulatory pressure. However. norepinephrine decreases venous return as there is a decrease in the mean circulatory pressure.
• Skeletal muscle contraction: Skeletal muscle contraction promotes venous return. Muscle contraction compresses the veins which have one way valve helping in the venous return process by which more blood flows back to the heart.

Hence, all the three above (breathing/inspiration, epinephrine / norepinephrine, skeletal muscle contraction) affect venous return.

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