How do impulses cross the synapse?

1 Answer
Dec 5, 2017


By means of chemical messenger called neurotransmitters.


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 actin 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 #Na^+# ions.
  • Thus, they start an action potential in the postsynaptic neuron.
    enter image source here
This is how the two neurons work...

Hope it helps...