physiology of the skeletal neuromuscular junction

Question 1

what innervates the skeletal muscle

Answer 1

alpha-motor neurones with myelinated axons and cell bodies in the spinal cord or brain stem

Question 2

what is the motor unit

Answer 2

neurone and the number of fibres that innervate it

Question 3

what does the axon divide into when it gets closer to the muscle

Answer 3

axon –> unmyleinated branches –>fine branches that end in a terminal bout that forms a chemical synapse with the muscle membrane at the neuromuscular junction

Question 4

what is the neurotransmitter released to the muscle

Answer 4

acetylcholine

Question 5

what are the key steps in neurotransmitter transmission

Answer 5

• synapse of ACh in cytoplasm of bouton
• uptake of ACh into synaptic vesicles for concentration and storage
• Ca2+ dependant release of ACh into synaptic cleft by exocytosis
• brief activation of nicotinic ACh receptors (nAChRs) by reversible binding of ACh
• rapid termination of transmitter action by acetylcholinesterase (AChE)

Question 6

what is the pre synaptic process of neuromuscular transmission

Answer 6

Choline is transported into the terminal by the choline transporter. ACh is synthesised in the cytosol from choline and acetyl coenzyme A by the enzyme choline acetyltransferase. ACh is concentrated in vesicles by the vesicular ACh transporter. ………