Nervous coordination (A-level only)

Medium
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Question 17
Medium

Figure 1 shows a schematic diagram of a cholinergic synapse.

Detailed schematic diagram of a cholinergic synapse showing a presynaptic terminal bulb positioned above a postsynaptic membrane. Label A points to a mitochondrion inside the presynaptic bulb. Label B points to the presynaptic membrane boundary. Label C points to one of several neurotransmitter-containing vesicles in the bulb. Label D brackets the synaptic cleft between the two membranes.

a.

Name the parts labelled A to D to identify the key structural components of this synapse.

[2]
b.

Following the release of acetylcholine into the synaptic cleft, depolarisation of the postsynaptic membrane occurs. Describe the sequence of events, starting from the diffusion of acetylcholine across the cleft, that leads to the initiation of an action potential in the postsynaptic neurone.

[4]
c.

Inhibitory synapses cause hyperpolarisation of the postsynaptic membrane (for example, by opening ligand-gated chloride channels). Explain how hyperpolarisation inhibits synaptic transmission.

[2]

Nervous coordination (A-level only) Questions

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  2. /Biology
  3. /Nervous coordination (A-level only)