S & M Systems: The Motor Unit & Contractions

Question 1

A muscle can only contract when s_________ by an electrical i______ sent from the CNS (_______ __________ ________)

Answer 1

Stimulated
Impulse
Central nervous system

Question 2

What is a motor unit made up of?

Answer 2

Motor neurone

Muscle fibre it stimulates

Question 3

A SUMMARY:
A nerve impulse is conducted down the a___ to the synaptic cleft by an a_____ p_______. A n________________ called a___________ assists the nerve impulse across the gap into the muscle fibre. If the electrical charge reaches a t______ value, the muscle fibre will contract in an a__ __ ____ fashion.

Answer 3

Axon
Action potential 
Neurotransmitter 
Acetylcholine 
Threshold 
All or none

Question 4

N_____ i______ initiated in the m____ neurone cell body. Nerve impulse conducted down the a____ of the motor neurone by a nerve a____ _____ to the s_______ _____. N_____________ called a_________ is secreted into the synaptic cleft to conduct the nerve impulse across the gap. If the electrical charge is above a ________, the muscle fibre will contract. This happens in an ___ __ ____ fashion.

Answer 4

Nerve impulse 
Axon
Action potential 
Synaptic cleft 
Neurotransmitter 
Acetylcholine 
Threshold 
All or none