Neuromuscular Joints

Question 1

What is a neuromuscular joint

Answer 1

Point where a motor neurone meets a skeletal muscle fibre

Question 2

Why are there many neuromuscular junctions across a muscle

Answer 2

To ensure the muscle fibres contract rapidly and powerfully and simultaneously as simultaneously stimulated by APs

Question 3

What is a motor unit

Answer 3

All the muscle fibres supplied by a single neurone that act together

Question 4

Process of how nerve impulse transmitted to muscle

Answer 4

-nerve impulse received at neuromuscular junction causing synaptic vesicles to fuse with presynaptic membrane and release acetyl choline
-acetyl choline diffuses to postsynapric membrane (muscle fibre) increasing its permeability to sodium ions which enter post synaptic membrane causing it to depolarise(leading to contraction)
-acetyl choline broken down by acetyl choline esterase to ensure muscle not over simulated (run out of ATP)
-choline and ethanoic acid diffuse back into presynaptic neurone and recombined to form acetyl choline using energy from the mitochondria

Question 5

Similarities between neuromuscular junctions and cholinergic synapse

Answer 5

-have neurotransmitters that are transported by diffusion
-have receptors that on binding with the neurotransmitter cause an influx of sodium ions
-use a sodium-potassium pump to repolarise the membrane
-use enzymes to breakdown the neurotransmitter

Question 6

Differences between neuromuscular junction and cholinergic synapse

Answer 6

-one excitatory for neuromuscular, only links motor neurones to muscles and AP ends here and acetylcholine binds to receptors on membrane of muscle fibre
-cholinergic synapse may be excitatory or inhibitory, links motor/sensory/relay neurones to neurones/other effector organs, a new AP may be produced along another neurone, acetylcholine binds to receptors on membrane of post synaptic neurone