How does an action potential travel across a cholergenic synapse?
An action potential arrives at synaptic knob. This causes voltage-gated Ca2+ ion channels to open, resulting in an influx of Ca2+ ions diffusing into the synaptic knob. This then causes vesicles containing acetylcholine (neurotransmitter) to fuse with the pre-synaptic membrane and release the acetylcholine. Acetylcholine diffuses across the synaptic cleft and binds to the receptor sites on the Na+ ion channels on the post synaptic membrane. This causes the Na+ channels to open and so Na+ diffuse into the postsynaptic neurone. The post synaptic neurone depolarises resulting in a new action potential.
VF
Related Biology A Level answers
All answers ▸(b) Cigarette smoke contains nicotine. Nicotine is a vasoconstrictor that reduces the diameter of some blood vessels. (i) Using this information, explain why smoking increases the risk of developing cardiovascular disease (CVD). How do I approach this?
What is the difference between transcription and translation?
What are some of the non-specific, first-line immune defences in humans?
Explain the difference in the speed of conduction of an action potential along the length of a myelinated neurone and a non-myelinated neurone.