synapse quiz

presynaptic neuron

1st neuron, axon terminal

postsynaptic neuron

2nd neuron, usually dendrite, can be axon or soma in CNS

synaptic cleft

space between presynaptic & postsynaptic

synaptic vesicle

in axon terminal, contain neurotransmitters

neurotransmitters

protein used to communicate w postsynaptic membrane, synthesized in soma

2 places where synapse occur

neuron to neuron in CNS, neuromuscular junction

neuromuscular junction

acetylcholine (ACH) is neurotransmitter, causes muscle impulse instead of another nerve impulse, mechanism is same as neuron to neuron synapse

types of synapses

CNS- axodendritic, axosomatic, axoaxonic

protein channels

on postsynaptic membrane, facilitated ion diffusion

ST step 1

action potential reaches axon terminal of presynaptic neuron

ST step 2

repolarization opens ca++ gates on presynaptic membrane, ca++ diffuses into presynaptic neuron

ST step 3

Ca++ signals neurotransmitter released, synaptic vesicles fuse w membrane and dump contents

ST step 4

neurotransmitters bind to receptors on postsynaptic membrane

ST step 5

this opens channels so ions can diffuse

ST step 6

neurotransmitters are reclaimed into presynaptic vesicles or is denatured by an enzyme

esp

neurotransmitters causes na+ gates to open, depolarization of postsynaptic membrane occurs

ipsp

neurotransmitter causes cl- gate to open, postsynaptic membrane becomes more negative- hyperpolarization

control by CNS

each neuron may synapse w 1-100,00 other neurons, sum of all esp’s & ipsp’s determines if nerve impulse results

synapse overview

signal starts as electrical- nerve impulse

converted to chemical at synapse- neurotransmitters

then back to electrical on postsynaptic membrane