Chapter 1: Neuromuscular system

Question 1

Eye vs quadriceps muscles for muscle activation precision

Answer 1

Eye: one fiber per motor neuron, precise.
Quads: several hundred fibers per motor neuron. Less precise.

Question 2

All or none principle of muscle

Answer 2

All of the muscle fibers in the motor unit contract and develop force at the same time. There is no evidence that a motor neuron stimulus causes only some of the fibers to contract. Similarly, a stronger action potential cannot produce a stronger contraction.

Question 3

Muscle twitch

Answer 3

Brief contraction/ activation of muscle fibers from an action potential traveling down a motor neuron

Question 4

What happens when muscle fibers force reach max

Answer 4

Calcium released during a twitch is sufficient to allow optimal actin and myosin activation for maximal force, but calcium is removed before force reaches its maximum and the muscle relaxes.

Question 5

Tetanus

Answer 5

Stimuli delivered at so high a frequency that the twitches begin to merge and eventually completely fuse.

Question 6

Fast twitch vs slow twitch motor unit

Answer 6

Fast twitch- develops force and relaxes rapidly, short twitch time. Opposite for slow twitch

Question 7

Type 1 fibers: for fatigue, aerobic capacity, force development

Answer 7

Fatigue resistant, high capacity for aerobic energy supply, limited potential for rapid force development ( low myosin ATPase activity and low anaerobic power)

Question 8

Type 2 fibers: for fatigue, aerobic capacity, force development

Answer 8

fatigable, low aerobic power, rapid force development (high myosin ATPase activity, high anaerobic power)

Question 9

Type 2a fibers vs type 2x fibers

Answer 9

2a has greater capacity for aerobic metabolism and surrounded by more capillaries, more fatigue resistant.