What is Central Nervous System

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CENTRAL NERVOUS SYSTEM

Human central nervous system consists of 2 parts:

1. BRAIN

The brain is the primary center for regulating and co-coordinating body activities.

The largest part of the brain is the cerebrum. The cerebral hemispheres are the paired halves of the cerebrum. Each hemisphere is divided into four major lobes named for the cranial bones that overlie them.

Two other important parts of the brain are thalamus and hypothalamus, both these are present below the cerebrum. The thalamus is a large mass of gray matter that acts as a relay center for impulses that travel from receptors such as eye, ear or skin to the cerebrum. The gray matter of the brain and spinal cord refers to the collection of the cell bodies and dendrites that appear gray because they are not covered by the myelin sheath. The hypothalamus contains neurons that control the body temperature, sleep, appetite, sexual desire and emotions such as fear and pleasure. The hypothalamus also regulates the release of hormones from the pituitary gland at the base of the brain.

FUNCTIONS OF THE BRAIN

Cerebrum has many functions like all the thought process, judgment, and memory etc. takes place through it. Efferent cranial nerves carry motor impulses from the cerebrum to muscles and glands and these produce movement and activity.

The cerebellum is located beneath the posterior part of the cerebrum. Its function is to aid the coordination of voluntary movements and to maintain the balance, posture and muscular tone.

The pons varolii is a part of brain that means bridge. It contains nerve fibre tracts that connect the cerebellum and cerebrum to the rest of the brain.

The medulla oblongata is located at the base of the brain and connects the spinal cord with rest of the brain. Nerve tracts cross over in the medulla oblongata. For example, nerve cells that control the movement of the left side of the body are found in the right half of the cerebrum. These cells send out axons that cross over to the opposite side of the brain in the medulla oblongata and then travel down the spinal cord.

2. SPINAL CORD

The spinal cord is a column of nervous tissue extending from the medulla oblongata to the second lumbar vertebra with the vertebral column. It ends at the cauda equina, a fan of nerve fibres below the second lumbar vertebra of the spinal column. It carries all the nerves that affect the limbs and lower part of the body. It also acts as the pathway for impulses going to and from the brain.

A cross section of the brain reveals an inner section of the gray matter and outer region of the white matter conducting impulses to and from the brain.

Q.1. Human central nervous system consists of:

1. Brain
2. Spinal cord
3. Both
4. Cerebellum

Ans. c

Q.2. Forebrain includes:

1. Cerebellum
2. Pons
3. Cerebrum
4. Medulla

Ans. c

Q.3. Cerebellum is part of:

1. Forebrain
2. Midbrain
3. Hindbrain
4. Medullary brain

Ans. c

Q.4. All the thought process, judgment and memory is controlled by:

1. Cerebellum
2. Pons
3. Cerebrum
4. Medulla

Ans. c

Q.5. Spinal cord is present in the cavity of:

1. Brain
2. Vertebral column
3. Cerebrum
4. Cerebellum

Ans. b