Motor neurones and units

What are the key structures of the Central Nervous System (CNS)?

The key structures include the cell body, axons, and motor end plate.

Where is the cell body of a motor neuron located?

In the spinal cord.

What is the function of axons in motor neurons?

Axons branch off the cell body and send impulses to the motor end plate.

What is the motor end plate?

The motor end plate is where the action potential travels to stimulate a muscle.

What is a motor neuron?

A specialized cell that transmits nerve impulses from the CNS to muscle fibers.

What is the difference between a motor unit and a motor neuron?

A motor unit includes the muscle, while a motor neuron does not.

How does the number of muscle fibers in a motor unit relate to movement control?

The number of muscle fibers within a motor unit depends on the control a movement requires.

What determines the number of motor units recruited?

The size of the contraction required determines the number of motor units recruited.

What is an action potential?

An electrical impulse that acts as a signal.

How is a nerve impulse conducted in a motor neuron?

It is initiated in the motor neuron cell body and conducted down the axon to the synaptic cleft.

What neurotransmitter is secreted into the synaptic cleft during a nerve impulse?

Acetylcholine (Ach) is secreted to conduct the nerve impulse across the gap.

What happens if the electrical charge in a muscle fiber exceeds a threshold?

The muscle fiber will contract in an 'all or none' fashion.

What is the All or None Law in muscle contraction?

An individual muscle fibre will either contract completely and to its maximum extent, or not at all, once a stimulus exceeds its threshold potential.

How can we increase the strength of muscle contraction?

By recruiting more motor units, which involves the stimulation of additional motor units.

What is the advantage of having fewer muscle cells per motor unit?

It allows for the generation of precise movements.

What characterizes large motor units in muscles that generate gross movements?

A single neuron is connected to a large number of muscle cells.

How is muscle tone maintained?

By asynchronous stimulation of random motor units.