Motor unit

Motor neuron in general

specialised cells that transmit nerve impulses to group of muscle fibres

Motor unit

consists of motor neuron and its muscle fibres

How to remember motor unit process

MAN SAYS ALL

What does MAN stand for?

M- motor neuron
A- action potential
N- neuromuscular junction

What does SAYS stand for?

S- synpatic cleft
A- ach
Y- why is there a neurotransmitter
S- signal

What does ALL stand for?

All or none law

Motor neuron in MAN SAYS ALL

CNS sends nerve impulse to motor neuron
when activated
sodium diffused into axon
depolarisation
action potential triggered

Action potential

+electrical charge inside nerve and muscle cells
conducts nerve impulse to travel down axon to motor end plate

Neuromuscular junction

point where axons motor end plate meets muscle fibres

Synaptic cleft

gap between motor end plate and muscle fibre

Ach

neurotransmitter secreted into synaptic cleft

Why Ach?

helps signal cross gap
if electrical charge above threshold, muscle action potential is created

All or nothing law

if action potential reaches threshold, all muscle fibres will contract
if not they don’t contract