(a) What is a neuron? Draw a labeled diagram of a neuron.
(b) What is a synapse? What happens at the synapse between two neurons? How are messages carried across a synapse? Explicate with the help of a labeled diagram.

(a) A neuron also known as a nerve cell, is the structural and functional unit of the nervous system. It carries messages between the brain and other body parts. lt has three components: the dendrites, the cell body, and the axon.

(b) Synapses are minute gaps present in between the pairs of adjacent neurons over which nerve impulses pass by diffusion of chemicals called a neurotransmitter from one neuron to the next.

The synapse between two neurons allows the electrical impulse to pass in one direction only.

The process of carrying messages across a synapse is as follow:
The synapse comprises: the ending of one neuron (axon), the gap, the receiving end of the next neuron (dendrite). 
When a stimulus acts on the receptor (it stays in touch with the dendrites of the sensory neuron), a chemical reaction is initiated that produces an electrical impulse in the receptor. This electrical impulse travels from the dendrites of the sensory neuron (say A) to its cell body and, then, along its axon. 
When the electrical impulse reaches at the end of the axon of the sensory neuron, the electrical impulse releases chemical substances called neurotransmitters in a very small amount into the synapse between two adjacent neurons.
The neurotransmitter crosses the synapse and starts a similar electrical impulse in the dendrite of the next neuron.
By this way, the electrical impulse passes from one neuron to the next across the synapse.


Simply Easy Learning

Updated on: 06-Jan-2023


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