Synapses Flashcards
How does a action potential reach the CNS or effector?
it has to be passed between several neurones
the junction between two neurones (or a neurones and an effector) is called a synapse
How are impulses transmitted across a synapse?
using chemicals called neurotransmitters
What is the synaptic cleft?
the gap which separates the axon of one neurone from the dendrite of the next neurone
what is the presynaptic and postsynaptic neurone?
presynaptic - neurones along which the impulse has arrived
postsynaptic - neurone that receives the neurotransmitter
What is the synaptic knob? What are its featuyres
the swollen end of the presynaptic neurone
it contrains many mitochondria na dlarge amounts of endoplascmic reticulum to enable it to manufacture neurotransmitters
What are synaptic vesicles?
vesicles contraining neurotransmitters
the vesicles fuse with the presynaptic membrane and release their contents in the synaptic cleft
WHat are neurotransmitter receptorss?
receptor molecules which the neurotransmitter binds to in the postysynaptic membrane
What is a excitatory neurotransmitter?
these neurotransmitters result in the depolarisation of the postsynaptic neurone
if the threshold is reached in the post synaptic membrane an action potential is triggered
acetylcholine is an example of an excitatory neurotransmitter
What is a inhibitory neurotransmitter?
result in the hyperpolarisation of the postsynaptic membrane
this prevents an action potential being triggered
Gamma-aminobutyric acid (GABA) is an example of an imhibtory neutrotransmitter that is found in some synapses in the brain
