synapses Flashcards
what is a cholinergic synapse
a synapse that uses acetylcholine as its neurotransmitter
what is the small gap called beyween two neurones
a synaptic cleft
how big is a synaptic cleft
20 nm
describe the transmission across a synapse
an action potential arrives at the synaptic bulb
calcium channels open and calcium ions diffuse into the synaptic bulb
the calcium causes the synaptic vesicles to fuse with the presynaptic membrane
acetylcholine is then removed by exocytosis and it diffuses across the synaptic cleft
acetylcholine bind to the receptor site on the sodium ion channels in the post synaptic membrane
sodium ion channels open and diffuse into post synaptic membrane in post synaptic neurone
EPSP is generated, threshold potenitla is reached, and a new action potential is made and travels down post synaptic neurone
what is in a synaptic vesicle
acetylcholine
what is the function of the calcium ions diffusing into the synaptic bulb
cause synaptic vesicles to fuse with the membrane
what is acetylcholinesterase
enzyme which hydrolyses acetylcholinesterase into acetic acid and choline.
what happens when acetylcholine is broken down
transmission of signals is stopped and synapse doesnt continue to produce action potentials in post synaptic neurone
what happens to the acetic acid and choline after hydrolysed
they reenter the synaptic bulb by diffusion and are recombined to acetylcholine using atp from respiration. it is stored in synaptic vesicles for future use
what are the advantages of the presynaptic bulb
many mitochondria - produces atp from respiration
large amount of smooth endoplasmic reticulum- to package neurotransmitters into vesicles
lots of calcium voltage channels
what is different about the sodium ion channels in the post synaptic membrane
they have a special receptor site which is specific to acetylcholine
what features are common to all sensory receptors
respond to stimuli
act as energy transducer which establish generator potential
for example, when touching something, the mechanical energy from the touch is converted into electrical energy
