Motor neurons

Question 1

The electrical impulse pathway which results in a muscle contraction

Answer 1

• In order for a skeletal muscle to contract an electrical impulse is sent from the cns to the muscle.
• The electrical impulse travels through a motor neuron and connects to a group of muscle fibres. This together makes a motor unit.
• In a motor neuron, the dendrites connect to the spinal cord and pick up electrical signals. This signal then travels through the cell body to the axon which is protected via the myelin sheath (an insulator). There are breaks within the myelin sheath called nodes of ranvier, the electrical impulse jumps from node to node until it reaches the axon terminal.
• The axon terminal leads to the motor end plate where it meets a muscle fibre bundle. This connection of motor neuron to muscle is called the neuromuscular junction.
• In order to send an electrical nerve impulse action potential is required. This is an electrical charge sent via the brain or sensory neuron to the motor neuron.
• If the electrical charge from the action potential passes the threshold charge of the motor end plate (neuromuscular junction.) All the muscle fibres within that motor unit will contract. This is the all or none law.

Question 2

Muscle fibre

Answer 2

A muscle fibre is the name given to the cells that make up your muscles

Question 3

Motor unit

Answer 3

A motor unit is a motor neuron and all the muscle fibres that it stimulates

Question 4

The all or none law

Answer 4

Motor units experience