Question

Which of the following describes the production of red blood cells?

Select one:

a. The kidneys release erythropoietin which stimulates RBC production.

b. High oxygen levels stimulate the production of more red blood cells.

c. RBC production occurs in the lymph nodes.

d. The production of angiotensinogen is an intermediate step in making more red blood cells.

e. more than one answer is correct

Which of the following does NOT increase venous return to the heart?

Select one:

a. skeletal muscle pump squeezing blood through the veins

b. sympathetic nerve activity causing venous vasoconstriction

c. respiratory pump providing a pressure gradient between the lower veins and the chest veins

d. parasympathetic activity causing venous vasodilation

e. more than one answer applies

Which of the following statements is NOT true?

Select one:

a. Saltatory conduction occurs in myelinated nerve fibers.

b. Along any nerve cell membrane in between Schwann cells, action potentials are propagated by contiguous conduction.

c. Saltatory conduction is faster than contiguous conduction.

d. Myelin acts as an insulator to slow down the impulse.

Answer 1

1. A) The kidneys release erythropoietin which stimulates RBC production.Erythropoietin hormone is produced by the kidney which promotes the red blood cells formation by the bone marrow. erythropoietin is sensitive to low oxygen levels in the blood that travels through the kidney. Low oxygen level induces the production of erythropoietin from kidney which results in formation of RBC. RBC production occurs in bone marrow.

2) b. sympathetic nerve activity causing venous vasoconstriction. Vasoconstriction lead to decreased blood flow in veins resulting in decreased blood flow through vein.

Skeletal muscle pump squeeze the muscle resulting in increased blood flow through vein.respiratory pump providing a pressure gradient between the lower veins and the chest veins.Respiratory activity influences venous return to the heart.increasing the rate and depth of respiration promotes venous return and therefore enhances cardiac output. parasympathetic activity causing venous vasodilation resulting in increased blood flow in veins.

3) b. Along any nerve cell membrane in between Schwann cells, action potentials are propagated by contiguous conduction. Membrane acts as insulation for nerve fibre which prevents loss of electrical impulse through propogation in nerve fibre. Mylinated fibre shows saltatory conduction because of presence of myelin sheath, membrane depolarizes only in the demylenated portion of nerve fibre. Saltatory conduction is faster than contiguous conduction because throughout whole nerve fibre, depolarization occurs less frequently in mylenated fibre which decreases the loss of impulse.