Question

Draw (by hand) the steps involved in the release of acetylcholine (Ach) from a preganglionic nerve into the synaptic cleft

• Your drawing should include:
  • a presynaptic nerve with an drawing/explanation of an action potential
  • A drawing/explanation of the process by which Ach is released into the synaptic cleft
  • A drawing/explanation of what type of receptor Ach binds with (on the post synaptic nerve)
• • An explanation of how the body degrades/recycles Ach

• How is Ach involved in myasthenia gravis? Write 2-3 sentences on the pathophysiology of myasthenia gravis.

Answer 1

1. Diagram of release of Ach from a preganglionic nerve into synaptic cleft :-

Synaptic Vesicle & Preganglinic 7 Neave onon terminal Neutotrans- mitter (Ach) Voltage gated/ galed Ach Cart Channel ooth otch o Synaptica 'Cleft Neurotran- smitter re-upt- ake pump Neurotrans- mitter recep- tous Dendritic spiné V Post-synaptic density

Steps in neuromuscular transmission: 1) nerve action potential. 2) calcium entry into the presynaptic terminus. 3) release of Ach quanta. 4) diffusion of Ach across cleft. 5) combination of Ach with post-synaptic receptors and Ach breakdown via esterase. 6) opening of Na+/K+ channels (cation channels).

2. Degradation of Ach :-

Acetylcholine = Acetyl + choline

3. Myasthenia gravis is an autoimmune disease in which the antibodies attack the acetylcholine neurotransmitters at the neuromuscular junction .