Neuroscience Week 3: Motor Unit and Fiber types

Question 1

Motor Unit description

Answer 1

comprises a single motor neuron

and the

many muscle fibers it innervates

Question 2

Neuromuscular Junction

Answer 2

axon ends terminate on individual muscle cells

Question 3

How many motor units does a muscle typically have?

Answer 3

Multiple

Question 4

Innervation ratio

Answer 4

The number of muscle cells a single motor neuron innervates

Question 5

Small Innervation Ratio

Answer 5

Fine motor control

Question 6

Large Innervation Ratio

Answer 6

Gross motor control

Question 7

All or Nothing principle

Answer 7

all motor unit fibers contract simultaneously

Question 8

Muscle Twitch

Answer 8

the response of a motor unit to a single action potential

Question 9

Muscle Fiber Types

3 listed

Answer 9

Type I Slow oxidative fibers

Type II A Fast aerobic fibers

Type II B Fast Anaerobic Fibers

Question 10

Type I Slow Oxidative Fiber Fiber Color

Answer 10

Red

Question 11

Type I Slow Oxidative Fiber Metabolism

Answer 11

Aerobic

Question 12

Type I Slow Oxidative Fiber Contraction Velocity

Answer 12

Slow

Question 13

Type I Slow Oxidative Fiber Fatigue Resistance

Answer 13

Highest

Question 14

Type I Slow Oxidative Fiber Function

2 listed

Answer 14

• Endurance
• Posture Maintenance

Question 15

Type II A Intermediate Fast Aerobic Fiber Color

Answer 15

Red

Question 16

Type II A Intermediate Fast Aerobic Fiber Metabolism

Answer 16

Aerobic

Question 17

Type II A Intermediate Fast Aerobic Fiber Contraction Velocity

Answer 17

Fast

Question 18

Type II A Intermediate Fast Aerobic Fiber Fatigue Resistance

Answer 18

High

Question 19

Type II A Intermediate Fast Aerobic Fiber Function

Answer 19

Moderate intensity and duration

Question 20

Type II B Fast Anaerobic Fiber Color

Answer 20

White

Question 21

Type II B Fast Anaerobic Fiber Metabolism

Answer 21

Anaerobic

Question 22

Type II B Fast Anaerobic Fiber Contraction Velocity

Answer 22

Fast

Question 23

Type II B Fast Anaerobic Fiber Fatigue Resistance

Answer 23

Low

Question 24

Type II B Fast Anaerobic Fiber Function

Answer 24

• Intense
• Short duration

Question 25

A motor neuron comprises?

Answer 25

a cell body and an axon

Question 26

Axons of the motor neuron leaves the cell body of the motor neuron, which lies in the __________ of the spinal cord, and travels to ___________?

Answer 26

• Grey Matter
• Its target muscle

Question 27

Motor neuron axon branching

Answer 27

A single motor neuron’s axon branches and innervates numerous individual muscle fibers

Axons from a single neuron innervate muscle cells throughout the muscle; any given muscle has multiple motor units.

Question 28

Phases of a Muscle Twitch

Answer 28

• Latent period; depends on the distance from the motor neuron to the skeletal muscle fiber as well as the speed of transmission down the axon. No change in muscle tension during the latent period.
• Contraction period: tension rises steadily to reach maximum tension.
• Relaxation period; is typically longer than the contraction phase: The tension decreases.

Muscles typically shorten during the contraction phase, and re-lengthen during the relaxation phase.