Nervous System

The nervous system is a very complex system when compared with other systems. We read, write, sleep, think, smell, feel, see, hear, become happy and sad, etc. All these are possible due to the nervous system. It is made of special tissues known as nervous tissues. Nervous tissues are made of a neuron. Some neuron carries impulses from tissues to the brain and some carry impulses from the brain to the tissues. Nervous system is divided into 3 main parts, they are:

1. Central Nervous system
2. Peripheral Nervous system
3. Autonomic Nervous system

Central Nervous system

It is also divided into two main parts, they are:

1. Brain
2. Spinal cord

Brain

The brain is the main part of the central nervous system which is safely enclosed in the skull. The brain sends the message to organs and tissues and receives impulses from them. It consists of different parts, they are:

• Cerebrum: The cerebrum is the biggest part of the brain. This enables us accomplish the sympathy, to sense, to an image, to think, to remember, to smell, to taste, to touch and to feel.
• Cerebellum: The cerebellum is responsible for the coordination of muscle action to maintain the body structure. It is situated behind the pons Varolii and beneath the posterior portion of the cerebellum.
• Midbrain: The brain is situated between the cerebrum and the pons Varolii. It consists of nerve cells and nerve fibers which connect the cerebrum with lower parts of the brain and spinal cord.
• Pons Varolii: The pons Varolii is situated in front of the cerebellum, below the midbrain and above the medulla oblongata. It conveys the sensations and impulses between the brain and the spinal cord.
• Medulla Oblongata: Medulla Oblongata relays the impulses and messages between the upper brain and spinal cord. It has a cardiac center, the respiratory center, coughing and sneezing center.

Spinal cord

The spinal cord is the next organ of the central nervous system. It lies inside the vertebral Column. There are 31 pairs of spinal nerves coming out from the spinal cord and they are spread to different part of our body. It is the main center for reflex action.

Its functions are:

1. It is the center of the reflex action.
2. It communicates between the brain and all the parts of the body.

Peripheral Nervous system

There are 12 pairs of nerves coming out from the brain and 31 pairs of nerves are coming out from spinal cord function under a peripheral nervous system. Among these some carry impulses from the brain to organs or some carry impulses from organs to the brain, among these some nerves do both functions as mixed nerves.

Autonomic Nervous system:

The nervous system in our body that function without our conscience is known as an autonomic nervous system. It is divided into two nervous system, they are:

1. Sympathetic Nervous system: A part of the nervous system that serves to accelerate the heart rate, constrict blood vessels, and raise blood pressure.
2. Parasympathetic Nervous system: A part of the nervous system that serves to decrease the bodily functions such as heart rate, blood pressure etc. is called parasympathetic nervous system. The function of these two nerves is opposite to each other.For example, sympathetic Nervous system dilates pupil whereas parasympathetic nervous system constricts the pupil.