Question

Choose best answer

1. The primary movement of ions across the sarcolemma during an action potential that stimulates a skeletal muscle fiber to contract is:

a. sodium inward and potassium outward

b. sodium outward and potassium inward

c. both sodium and potassium inward

d. both sodium and potassium outward

2. The chemical substance that transmits the electrical impulse from the alpha motor neuron to the sarcolemma of the muscle fiber is:

a. norepinephrine

b. adrenalin

c. beta-endorphin

d. acetylcholine

3. The purpose of the skeletal muscle fiber's sodium-potassium pump is to:

a. initiate a muscle action potential to cause contraction

b terminate the muscle action potential to cause relaxation

c. maintain the concentrations of sodium and potassium inside and outside of muscle fibers

d. regulate the calcium concentration inside and outside of fibers by exchanging calcium for sodium and potassium

4. The correct sequence of the listed events during a single, normal cycle of contraction and relaxation of a skeletal muscle fiber is:

a. action potential, release of calcium from the SR, increased calcium binding to troponin, increased pumping of calcium by SR

b. action potential, increased pumping of calcium by SR, release of calcium from the SR, increased calcium binding to troponin, of calcium by SR, release of calcium from

c. action potential, increased pumping of calcium by SR, increased calcium binding to troponin, release of calcium from the SR

d. release of calcium from the SR, action potential, increased calcium binding to troponin, increased pumping of calcium by SR

Answer 1