anatomy 12 unit 4 (part 4 synapses) (copy)

synapse definition

where neurons communicate with each other

• action potential triggers presynaptic neuron to release neurotransmitters

neurotransmitters definition

chemicals that transmit nerve impulses across synaptic cleft

glial cells (synaptic support)

regulates concentration of neurotransmitters around synaptic cleft

• release ATP which help synaptic function

axon bulb

swollen terminal knobs on ends of axon terminal branches

presynaptic membrane

membrane of axon at synaptic ending

• sends impulse

postsynaptic membrane

dendrite membrane beyond presynaptic membrane

• recieves impulse

synaptic cleft

space between presynaptic and postsynaptic membranes

synaptic vesicles

transport neurotransmitters located near surface of synaptic endings

excitatory neurotransmitters

makes action potential happen (learning, rewards, feeling good)

• glutamate, acetylcholine, noradrenaline, dopamine

inhibitory neurotransmitters

prevents action potential from happening (sleep, fine tune neural processing)

• GABA, glycine, serotonin

action potential requirements

more excitatory neurotransmitters than inhibitory neurotransmitters binding at postsynaptic membrane

5 steps of synaptic transmission

1. contractile proteins pull synaptic vesicles to presynaptic membrane

2. vesicles fuse with presynaptic membrane

3. neurotransmitters released into synaptic cleft through exocytosis

4. neurotransmitters diffuse across synaptic cleft

5. binding of neurotransmitters to specific receptors on postsynaptic membrane, opening ion channels

neurotransmitter deactivation process

neurotransmitter degraded by enzymes

• to prevent neurotransmitters from continuously acting on postsynaptic membrane

ion which begins process of moving synaptic vesicles toward presynaptic membrane

calcium