Physiology: NMJ and Myasthenia Gravis

Question 1

What type of receptors are involved in the NMJ?

Answer 1

Nicotinic AChR (ionotropic)

Question 2

What terminates the transmission of the AP?

Answer 2

ACh esterase which breaks down Ach into esterase and cholline

Question 3

What component of ACh is taken up for resynthesis in the pre-synaptic bouton?

Answer 3

Choline

Question 4

Where is the end plate of the NMJ positioned in a muscle?

Answer 4

In the middle of a muscle so that the AP propagates away on both sides. This maintains the structural and functional integrity of a muscle.

Question 5

What are the key differences of NMJ compared to neuron-neuron synapses?

Answer 5

Each muscle fibre gets input from only one motor neuron

Each single AP in motor axon can create a suprathreshold (EPSP) in a muscle fibre - big enough to give AP