Role of Neurotransmitters at Synapses

Synapse

A tiny gap between two neurones

Neurotransmitter

Chemical that carries impulses across a synapse

Vesicles

Small sacs in the presynaptic neurone containing neurotransmitters

Presynaptic neurone

Neurone sending the impulse

Postsynaptic neurone

Neurone receiving the impulse

Receptor proteins

Proteins on the postsynaptic membrane that bind neurotransmitters

Electrical impulse

Signal travelling along a neurone

Diffusion

Movement of neurotransmitters across the synaptic gap

Synaptic cleft

The gap between neurones at a synapse

Enzymes (in synapse)

Break down neurotransmitters after transmission

What is a synapse?

A small gap between two neurones

What crosses a synapse?

Neurotransmitters

Where are neurotransmitters stored?

In vesicles in the presynaptic neurone

What happens when an impulse reaches the end of a neurone?

Vesicles release neurotransmitters into the synaptic cleft

How do neurotransmitters cross the synapse?

They diffuse across the gap

What happens when neurotransmitters reach the postsynaptic neurone?

They bind to receptor proteins

What does binding to receptors cause?

A new electrical impulse in the postsynaptic neurone

Why are neurotransmitters broken down after use?

To stop continuous stimulation

What breaks down neurotransmitters?

Enzymes in the synaptic cleft

Why are synapses important?

They ensure impulses travel in one direction

Why can drugs affect synapses?

They alter neurotransmitter release, breakdown, or receptor binding

Why is diffusion important at synapses?

It allows neurotransmitters to move across the gap

What ensures impulses don’t jump directly between neurones?

The synaptic cleft