What is a cholinergic synapse?
A synapse that transmits a signal between neurones using acetylcholine.
AQA A-Level Biology - (7402) · 3.6.2.2
Revise AQA A-Level Biology - (7402) specification point 3.6.2.2, Synaptic transmission (A-level only), with free active-recall flashcards. Flip through the set or review every question and answer below.
1 / 10
What is a cholinergic synapse?
A synapse that transmits a signal between neurones using acetylcholine.
What two structures does a cholinergic presynaptic terminal contain?
Mitochondria and vesicles containing acetylcholine.
What does an arriving action potential cause at a cholinergic presynaptic terminal?
It opens voltage-gated calcium ion channels, allowing calcium ions to enter.
How does calcium entry cause acetylcholine release from a presynaptic terminal?
It causes vesicles to fuse with the presynaptic membrane and release acetylcholine by exocytosis.
How does acetylcholine open sodium ion channels at a cholinergic synapse?
It diffuses across the cleft and binds to postsynaptic receptors, opening ligand-gated sodium ion channels.
What produces an excitatory postsynaptic potential at a cholinergic synapse?
Sodium ions enter the postsynaptic neurone, causing a local depolarisation.
When can an action potential be generated in the postsynaptic neurone?
When the depolarisation reaches threshold.
How is acetylcholine’s action in the synaptic cleft ended?
Acetylcholinesterase hydrolyses acetylcholine.
What happens to choline after acetylcholine is broken down at a synapse?
It is taken back into the presynaptic terminal and used to resynthesise acetylcholine, which is repackaged into vesicles.
Why is transmission across a cholinergic synapse unidirectional?
Acetylcholine is released from the presynaptic terminal, while its receptors are on the postsynaptic membrane.