Explain how an action potential is transmitted across a cholinergic synapse.

The action potential arrives at the synaptic knob of the presynaptic neurone. The action potential stimulates the opening of voltage-gated calcium ion channels in the presynaptic neurone, allowing calcium ions to diffuse into the synaptic knob. The influx of calcium causes synaptic vesicles containing acetyl choline (ACh) to move towards the presynaptic membrane. These vesicles fuse with the membrane and release ACh into the synaptic cleft by exocytosis. ACh diffuses across the synaptic cleft and binds to specific cholinergic receptors on the postsynaptic membrane. This causes sodium ion channels to open on the postsynaptic neurone. Sodium diffuses into the postsynaptic neurone, causing depolarisation. If there is a sufficient influx of sodium, the depolarisation will be sufficient to reach the threshold potential and an action potential will be generated on the postsynaptic membrane. ACh is broken down in the synaptic cleft by Acetylcholinesterase (AChE) and the products are reabsorbed into the presynaptic neurone to make more ACh.

KE
Answered by Kathryn E. Biology tutor

2253 Views

See similar Biology A Level tutors

Related Biology A Level answers

All answers ▸

Discuss the endocrine and exocrine functions of the pancreas.


What is the difference between DNA transcription and translation?


What is the main function of the Schwann cell?


Albumin (a globular protein) is a solute found in blood plasma. In liver disease, people cannot produce sufficient amounts of albumin. Describe and explain how this change would affect red blood cells.


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences