Question

The functional unit of nervous tissue is called
(a) Cyton
(b) Synapse
(c) Neuron
(d) Axon

Answer 1

Hint: Neural system of all animals is composed of highly specialized cells that transmits the impulses from tissues or organs to CNS and vice versa.

Complete answer:
Neurons are the structural and functional unit of the nervous system because the various functions of the nervous system are conducted by the neurons. A neuron is a microscopic structure and is composed of three major parts, cell body or soma, Dendrites, and Axon.
- Neurons are also called nerve cells.
- On average, the human brain is made up of more than 100 billion neurons.
- The cell body is the controlling part of the neuron. It contains Cytoplasm with a nucleus in the center.
- The cytoplasm of the cell body contains typical cell organelles like the Golgi apparatus, Endoplasmic reticulum, Ribosomes, etc.
- The cytoplasm contains certain granular bodies called Nissl’s granule.
- Dendrites are short fibers arising out of the cell body.
- Dendrites branch repeatedly to further give rise to smaller fibers. The dendrites of one neuron receive the electrical impulses from different sources then transmit these impulses towards the cell body of the neuron.
- a long fiber- like structure that arises from the cell body is called Axons.
- Each neuron may have many dendrites but has only one long fiber- like axon.
- Each axon terminal terminates as a bulb- like structure called synaptic knob.
- There are two types of axons: Myelinated axons, and Unmyelinated axons.
- Myelin sheath is laid down by Schwann cells. These sheets are not continuous. The gaps present between two adjacent myelin sheaths is called a node of Ranvier.
So, the correct answer is ‘Neuron’.

Note: Do not confuse the terms neurons and nephrons. - Neurons are the structural and functional unit of the nervous system which carries electrical impulses whereas nephrons are the structural and functional unit of the Kidney which filters blood.
- Also, while neurons are called nerve cells, the axon is known as a nerve fiber.