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Control and Coordination

Endocrine Glands And Their Functions

Do you know which organs make up the nervous system?

The nervous system is made up of the brain, spinal chord, and nerve cells or neurons.

Let us first study about the structure of the functional units of the nervous system i.e., the neurons.

Structure of a neuron

The three main parts of a neuron are the axon, dendrite, and cell body. The axon conducts messages away from the cell body. The dendrite receives information from the next cell and conducts it towards the cell body. The cell body contains the nucleus, mitochondria, and other organelles. It is mainly concerned with maintenance and growth of the cell.

Arrangement of neurons

Neurons are arranged end to end, forming a chain. This helps in the continuous transmission of impulses. Each neuron receives an impulse through its dendrite and transmits it to the next neuron in a sequence through its axon.

Neurons are not connected. Synapse or a small gap occurs between the axon of one neuron and dendron of the next neuron.

A synapse in the muscle fibre is also known as neuromuscular junction. Let us discuss the working of a synapse in detail.

Types of neurons

Neurons are of three types.

How does a nerve impulse travel?

The dendrite end of the neuron collects information and triggers a chemical reaction, which results in an electric impulse. This impulse is transmitted from the dendrite to the cell body and then to the axon. From the axon, the impulse travels to its end, where the electrical impulse sets off the release of some more chemicals. These chemicals cross the synapse and start a similar electrical impulse in the dendrite of the next neuron. In this way, impulses are transmitted from one neuron to another to finally reach the brain.

In a similar manner, impulses are transmitted from the brain to muscle glands.

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The body performs various activities. All these activities are controlled by the brain. How does the brain control all activities? Are there any divisions in the brain, which take over the control of different activities?

Do you know which organs make up the nervous system?

Let us explore.

The nervous system is divided into - central nervous system (CNS) and peripheral nervous system (PNS). The CNS consists of the brain and spinal chord while the PNS consists of the nerves that connect the central nervous system to different parts of the body.

The central nervous system receives information from all parts of the body and also sends information to the muscles. Communication between the CNS and body parts is facilitated by the nerves of PNS.

The important components of nervous system are:

The Central Nervous System

The central nervous system consists of the brain and the spinal cord. The brain is enclosed in a bony box called the cranium and spinal cord is protected by vertebral column. The brain and spinal cord are externally covered by protective covering called meninges. It is made up of three layers namely duramater (outer layer), arachnoid (middle layer), piamater (inner layer). The space between meninges is filled by a watery fluid called cerebro-spinal fluid (CSF). This fluid flows from the brain to spinal cord and then back to brain. It acts as a shock absorber and protects brain form injuries. It also provides nutrients to the cell...

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