How do presynaptic and postsynaptic neurons work?
Answers
Series of steps in Synaptic Transmission:
The nerve impulse arrives at presynaptic neuron and starts an action potential in it.
This action potential can not jump from one neuron to the next neuron.
So, there must be a mechanism for its transmission. And ofcourse there is an amazing mechanism set by Nature which is Synaptic transmission, which occurs through synapse.
Synapse is a microscopic gap between axon-ending of presynaptic neuron and dendrite-ending of postsynaptic neuron.
The pre-synaptic neuron has synaptic vesicles in its synaptic knob.
These synaptic vesicles are filled with special type of chemical messenger called neurotransmitters, which offer great services in the transmission of the action potential.
Thus, the action potential when arrives at the axon-ending of presynaptic neuron , the synaptic vesicles fuse with synaptic membrane. As a result of this fusion, neurotransmitters are released in the synaptic cleft(gap).
The membranes(of dendrites) of post-synaptic neuron have receptors .
The neurotransmitters released from the presynaptic neuron binds to the receptors of the postsynaptic neuron.
These neurotransmitter change the permeability of postsynaptic neuron for certain ions i.e
N
a
+
ions.
Thus, they start an action potential in the postsynaptic neuron.
Explanation:
Ohm's Law is a formula used to calculate the relationship between voltage, current and resistance in an electrical circuit. To students of electronics, Ohm's Law (E = IR) is as fundamentally important as Einstein's Relativity equation (E = mc²) is to physicists. E = I x R.