Receptors And Synapses

Question 1

How does an action potential pass from one neurone to another at a synapse?

Answer 1

• an action potential arrives at the end of the presynaptic neurone which causes calcium channels in the membrane to open and calcium floods into the axon terminal
• the increased level of calcium in the cell stimulates the synaptic vesicles to move towards the membrane of the presynaptic neurone. These vesicles contain the neurotransmitter acetylcholine.
• The vesicles fuse with the presynaptic membrane. Acetylcholine is released into the synaptic cleft.
• acetylcholine diffuses across the synaptic cleft. It binds to receptors on sodium ion channels on the postsynaptic neurone, which results in the channels opening and sodium flooding in.
• The postsynaptic membrane depolarises and if the threshold value is reached an action potential is generated.