Question

7. In a normal muscle which has been stimulated, which of the following lasts the longest?

a. refractory period   b. latent period    c. action potential

d. period of contraction and relaxation (muscle twitch)

8. Which of the following would result in the smallest force of contraction following stimulation?

a. a muscle half its normal resting length

b. a muscle twice its normal resting length

c. a muscle that is at its normal resting length

d. a muscle in which the passive force greatly exceeds the active force

9. Which of the following would be true about a muscle with mostly large motor units (as opposed to a muscle with mostly small motor units)?

a. controls movements much more precisely than a muscle with small motor units

b. contains a larger number of motor neurons

c. each neuron controls a large number of muscle fibers

d. muscles with large motor units contain only oxidative fibers

e. all of the above are true

10. Running a marathon or longterm maintenance of muscle tone (as opposed to sprinting or heavy lifting) would most depend on

a. utilizing creatine phosphate    b. anaerobic glycolytic metabolism

c. aerobic respiration

11. Which of the following would not be true about lactic acid?

a. produced when glycolysis occurs under anaerobic conditions

b. the more rapidly a muscle contracts the more lactic acid is produced

c. produced by myoglobin

d. secreted into the blood

e. converted by the liver into glucose and glycogen

Answer 1

7. d. period of contraction and relaxation (muscle twitch)

Explanation: Period of contraction and relaxation (muscle twitch) is the mechanical event in the muscle stimulation and contraction hence it lasts for longer period.

8. a. a muscle half its normal resting length

Explanation: force of contraction produced by the muscle is directly proportional to the initial length of the contratile muscle fibers.

Lower the length lesser will be the force of contraction.

9. c. each neuron controls a large number of muscle fibers

Explanation: Motor unit is the motor nerve and its innervating all the muscle fibers.

Larger motor units is the one in which one motor neuron is innervating large number of muscle fibers.

10) c. aerobic respiration

Explanation: Merathon runners have more slow twitch oxidative fibers hence they are mostly dependent on aerobic respiration.

11.b. the more rapidly a muscle contracts the more lactic acid is produced

Explanation: Lactic acid is produced by the anaerobic respiration. When a muscle is more rapidly contracting, more anaerobic respiration occur generating more lactic acids.