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5.3 Neuronal Communication > Synapses 1 > Flashcards

Flashcards in Synapses 1 Deck (17):

What is a cholinergic synapse?

A synapse that uses acetylcholine as its neurotransmitter.


What is a neurotransmitter?

A chemical used as a signalling molecule between two neurones in a synapse.


What is a synapse?

A junction between two or more neurones, where one neurone can communicate with, or signal to, another neurone.


What is the name of the small junction at the synapse?

The synaptic cleft.


What is the swelling called at the end of the pre-synaptic neurone?

The pre-synaptic bulb.


Why does the pre-synaptic bulb contain mitochondria?

It indicates that an active process needing ATP is involved.


Why does the pre-synaptic bulb contain a large amount of smooth endoplasmic reticulum?

They package the neurotransmitter into vesicles.


What does the post-synaptic membrane contain?

Specialised sodium ion channels that can respond to the neurotransmitter.


What happens when acetylcholine is present in the synaptic cleft?

It binds to the receptor sites on the sodium gated channels on the post-synaptic bulb.


Describe the structure of the receptors of the sodium-gated channels.

Five protein subunits make up the sodium channel. Two of these polypeptides have a special receptor site that is specific to acetylcholine.


What happens when an action potential arrives at the synaptic bulb?

The voltage-gated calcium ion channels open. This causes the calcium ions to diffuse into the synaptic bulb.


What does the influx of calcium ions cause?

The synaptic vesicles to move to, and fuse with, the pre-synaptic membrane.


What is contained/released by the vesicles?



What happens once the acetylcholine binds to the receptors on the post-synaptic membrane?

The sodium-gated channels open. Sodium ions diffuse across the post-synaptic membrane into the post-synaptic neurone.


What happens as a result of the influx of sodium ions?

A generator potential or excitatory post-synaptic potential is created.


What happens when enough generator potentials are created?

If sufficient generator potentials combine then the potential across the post-synaptic membrane reaches the threshold potential. A new action potential is created in the post-synaptic neurone.


What is the role of acetylcholinesterase?

It is an enzyme found in the synaptic cleft. It hydrolyses the acetylcholine to ethanoic acid (acetic acid) and choline. It stops the transmission of further action potentials.