For DVM scholars

2.  Synapsis means “juncture”.
 Junction between any two excitable cells or neurons
Types
ELECTRICAL SYNAPSES
In an electrical synapse, two neurons are connected
by gap junctions .
o . Lead to unbroken transmission of electrical signals
o Extremely rapid and Unregulated.
o rare in the human nervous system.
o They are in specialized locations, such as the pulp of a
tooth and the retina of the eye.
o Numerous in smooth muscle and cardiac muscle.
CHEMICAL SYNAPSES
A chemical synapse involves a junction between an
axon terminal of one neuron(presynaptic neuron) and the
dendrites or cell body of a second neuron(postsynaptic
neuron).
o Majority of synapses in the human nervous system
o Some neurons in the CNS receive as many as 100,000
synaptic inputs .

3.  Action potential reaches axon terminal of presynaptic neuron.
 Depolarization of membrane of terminal buttons
 Activation and opening of Voltage-gated channels
 Ca2+ enters synaptic knob (presynaptic axon terminal).
 Neurotransmitter ACh is released by Calcium mediated
exocytosis into synaptic cleft.
 Neurotransmitter binds to receptors that are an integral part of
chemically gated channels on sub synaptic membrane of
postsynaptic neuron.
 Binding of ACh to ACh receptors in the endplate membrane
opens that specific channel.
 Na+ influx resulting in local depolarization and formation of
endplate Potential(EPP)
 Receptor site opens and allows Na+ to enter dendrite triggering
Action Potential
 Spread of action potential to T-Tubule
 Remaining Neurotransmitters either dissolved by enzymes or
recycled to sending neuron through reuptake