Neuroscience Week 3: Motor Unit and Fiber types Flashcards
Motor Unit description
comprises a single motor neuron
and the
many muscle fibers it innervates
Neuromuscular Junction
axon ends terminate on individual muscle cells
How many motor units does a muscle typically have?
Multiple
Innervation ratio
The number of muscle cells a single motor neuron innervates
Small Innervation Ratio
Fine motor control
Large Innervation Ratio
Gross motor control
All or Nothing principle
all motor unit fibers contract simultaneously
Muscle Twitch
the response of a motor unit to a single action potential
Muscle Fiber Types
3 listed
Type I Slow oxidative fibers
Type II A Fast aerobic fibers
Type II B Fast Anaerobic Fibers
Type I Slow Oxidative Fiber Fiber Color
Red
Type I Slow Oxidative Fiber Metabolism
Aerobic
Type I Slow Oxidative Fiber Contraction Velocity
Slow
Type I Slow Oxidative Fiber Fatigue Resistance
Highest
Type I Slow Oxidative Fiber Function
2 listed
- Endurance
- Posture Maintenance
Type II A Intermediate Fast Aerobic Fiber Color
Red
Type II A Intermediate Fast Aerobic Fiber Metabolism
Aerobic
Type II A Intermediate Fast Aerobic Fiber Contraction Velocity
Fast
Type II A Intermediate Fast Aerobic Fiber Fatigue Resistance
High
Type II A Intermediate Fast Aerobic Fiber Function
Moderate intensity and duration
Type II B Fast Anaerobic Fiber Color
White
Type II B Fast Anaerobic Fiber Metabolism
Anaerobic
Type II B Fast Anaerobic Fiber Contraction Velocity
Fast
Type II B Fast Anaerobic Fiber Fatigue Resistance
Low
Type II B Fast Anaerobic Fiber Function
- Intense
- Short duration
A motor neuron comprises?
a cell body and an axon
Axons of the motor neuron leaves the cell body of the motor neuron, which lies in the __________ of the spinal cord, and travels to ___________?
- Grey Matter
- Its target muscle
Motor neuron axon branching
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.
Phases of a Muscle Twitch
- 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.
