5.3.8 The Role of Synapses Flashcards
What is a synapse?
The junction where two neurones meet is known as a synapse
A synapse consists of a presynaptic knob, synaptic cleft and postsynaptic membrane
Synapses that use acetylcholine (ACh) as a neurotransmitter are described as cholinergic synapses
What is transmission at a synapse?
Electrical impulses cannot ‘jump’ across synapses
When an electrical impulse arrives at the end of the axon on the presynaptic neurone (also called the synaptic knob), chemical messengers called neurotransmitters are released from vesicles at the presynaptic membrane
The neurotransmitters diffuse across the synaptic cleft and temporarily bind with receptor molecules on the postsynaptic membrane
This stimulates the postsynaptic neurone to generate an electrical impulse that then travels down the axon of the postsynaptic neurone
The neurotransmitters are then destroyed or recycled to prevent continued stimulation of the second neurone, which could cause repeated impulses to be sent
