Structure and function of synapse Flashcards
What is a synapse?
The point at which one neuron communicates with the dendrite of another, or with an effector, is called a synapse
form a junction between one NEURONE and the
next
Can nerve impulses pass through a gap
No
How is action potential transmitted?
by means of a chemical called a neurotransmitter
What are the Functions of Synapses?
1) A single impulse along one neuron to be transmitted to a number of different neurons at a synapse,
allowing a single stimulus to create some simultaneous responses
2) A number of impulses may be combined at a synapse, allowing stimuli from different receptors to interact in order to produce a single response
FOR THE STRUCTURE OPEN THE POWERPOINT MAHRAN
FOR THE STRUCTURE OPEN THE POWERPOINT MAHRAN
What is the neurotransmitter made by?
Where is it stored?
the pre-synaptic neuron
stored in synaptic vesicles at the
end of the axon
What happens when the action potential reaches the synaptic
knob?
the neurotransmitter in a vesicle migrates
to the membrane and is released and diffuses
across the synaptic cleft
What does the membrane of the post-synaptic neuron have?
What are their characteristics?
chemical-gated ion channels called
neuroreceptors
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These have specific binding
sites for neurotransmitters. This sets up a new action potential.
What do Synapses that have
acetylcholine transmitters are called?
cholinergic synapses
What is spatial summation?
A number of neurons all release enough neurotransmitter to exceed the threshold and trigger an action
potential in the next neuron
What temperoal summation?
One neurone releases the neurotransmitter many times over a short period of time to exceed the threshold and trigger an action potential in the next neuron
whats unidirectionality?
Synapses can only pass in one
direction – from the presynaptic to the postsynaptic
neurone
What are Inhibitory Ion Channel Synapses?
1- Some synapses have chloride (Cl-
)channels that can be opened
2- When the channels open, negative ions flow in causing a local hyperpolarisation (more negative than resting potential) and making an action potential less likely.
3- So with these synapses an impulse in one neurone can inhibit an impulse in the next
Whats Acetylcholine ?
common
neurotransmitter.
what is Acetylcholinesterase ?
is a cholinergic enzyme primarily found at postsynaptic neuromuscular
junctions, especially in muscles and nerves.
It immediately breaks down or hydrolyzes acetylcholine, a naturally occurring neurotransmitter,
into acetic acid and choline.
