Structure and function of synapse bio

Synapse

The point where one neurone communicates with another or with an effector.

Neurotransmitter

Chemicals that transmit information, but not impulses, from one neurone to another.

Synaptic cleft

The small gap, 20-30nm wide, that separates neurones and is the site of communication.

Presynaptic neurone

The neurone that releases the neurotransmitter at the synapse.

Synaptic knob

The swollen portion at the end of the axon of the presynaptic neurone.

Postsynaptic neurone

The neurone that receives the neurotransmitter at the synapse.

Excitatory synapse

A synapse that causes the generation of a new action potential.

Cholinergic synapse

A synapse that uses acetylcholine (Ach) as the neurotransmitter.

Unidirectionality

The property of synapses to pass information in one direction, from presynaptic to postsynaptic neurone.

Summation

The process of rapidly building up neurotransmitter concentration in the synapse to trigger a new action potential.

Spatial summation

Multiple presynaptic neurones releasing enough neurotransmitter to exceed the threshold value of the postsynaptic neurone.

Temporal summation

A single presynaptic neurone releasing neurotransmitter many times over a short period to exceed the threshold value of the postsynaptic neurone.

Inhibitory synapse

A synapse that makes it less likely for a new action potential to be created on the postsynaptic neurone.

Hyperpolarisation

The increase in membrane potential that makes it less likely for a new action potential to be generated.

Function of synapses

To transmit information from one neurone to another, allowing for initiation of new impulses and combination of multiple impulses.