Neuromuscular System

Question 0

All-or-none principle

Answer 0

All of the muscle fibers in the motor unit contract and develop force and develop force at the same time. There is no such thing as a motor neuron stimulus that cause only some of the fibers to contract. Similarly, a stronger action potential cannot produce a stronger contraction. ex (once a sufficient amount of pressure is place on the trigger, the gun fires; however, squeezing the trigger harder will not cause the bullet to go faster)

Question 1

Acetylcholine

Answer 1

A neurotransmitter which diffuses across the neuromuscular junction, causing excitation of the sarcolemma

Question 2

Twitch

Answer 2

A short period of activation of the muscle fibers within the motor unit resulting from action potential traveling down a motor neuron

Question 3

Tetanus

Answer 3

a condition where stimuli may be delivered at so high a frequency that the twitches begin to merge and eventually fuse. This is the maximal amount of force the motor unit can develop

Question 4

Slow-twitch muscle fiber

Answer 4

Muscle fibers that develops force and relaxes slowly; long twitch time

Question 5

Fast-twitch-fiber

Answer 5

Muscle fiber that develops force and also relaxes rapidly; short twitch time.

Question 6

Type I

Answer 6

Slow-twitch muscle

Question 7

Type IIa

Answer 7

fast-twitch muscles

Question 8

Type IIx

Answer 8

New name for type IIb; fast twitch

Question 9

Recruitment

Answer 9

A means of varying skeletal muscle force by varying the number of motor units activated

Question 10

Preloading

Answer 10

To activate some of the muscle fibers that are active early in the range of motion the muscle must be loaded prior to muscle action. This occurs when weights are lifted.

Question 11

Proprioceptors

Answer 11

Specialized sensory receptors located within the joints, muscles, and tendons, that relay information concerning muscle dynamics to the conscious and unconscious parts of the central nervous system

Question 12

Muscle spindles

Answer 12

Proprioceptors that consist of several modified muscle fibers enclosed in a sheath of connective tissue

Question 13

Intrafusal fibers

Answer 13

Modified muscle fibers the run parallel to normal fibers

Question 14

Extrafusal fibers

Answer 14

Normal muscle fibers

Question 15

Golgi tendon organs (GTOs)

Answer 15

proprioceptors located in tendons near the myotendinous junction and are in series (attached end to end) with extrafusal muscle fibers. They are activated when the tendon attached to an active muscle is stretched