Synapses Flashcards
Does mylination or axon diameter have a greater effect on speed of an impulse?
Myelination.
What are the two types of synapse?
Electrical synapses and chemical synapses.
What are the differences between the two types of synapse?
Electrical synapses have pre and post synaptic neurones that are directly connected by gap junctions, whereas chemical synapses are physically separated by a space.
electrical synapses allow local currents from arriving APs to flow directly across the junction, very rapid
What are axodendritic synapses?
Between the axon of one neurone and the dendrites of another.
What are axosomatic synapses?
Between the axon terminals of one and the cell body of another.
What are axoaxonal synapses?
Between two axons.
What are the two types of neurotransmitter receptors?
Ligand-gated ion channels and G-protein coupled receptors.
How are ligand-gated channels opened?
The neurotransmitter binds to the receptor, activated resulting in a conformational change such that it forms an open channel
How are G-protein coupled receptors opened?
A neurotransmitter binding to a receptor that contains and G-protein attached that then binds to an effector protein that sends intracellular messages to a voltage-gated ion channel so that it opens.
Where does Ach act?
Muscarinic or nicotinic receptors. Muscarinic are G-protein coupled and nicotinic receptors are ion channel receptors.
What enzyme synthesises Ach?
Choline acetyl transferase.
What enzyme breaks down Ach?
and where?
acetylcholinesterase, in the cleft
How is ACh formed?
Choline and acetyl CoA combining.
What are the breakdown products of ACh?
Choline and acetic acid.
Why are neuromuscular junctions used as a model synapse?
They are easy to experiment with and study - they are simple as there is only one input and one output.
