4th Class Science Our Body Nervous System

Nervous System

Category : 4th Class

*     Nervous system

 

Nervous system co-ordinates all our body functions. It consists of brain, spinal cord and the nerves. Brain is our body's control system. Brain sends messages and receives them from all organs, all over the body. Brain is divided into 3 parts

        Human Brain

Accounts for 85% of our brain's weight. It consists of two -halves, right half and left half. The right half, which helps to think about things like colour, different shapes, etc. The left half is responsible for speech, maths, and logic. It is also known as the forebrain.

 

*         Cerebellum

It is also called the Hindbrain, and is much smaller than forebrain. It is responsible for the movement of our body and maintaining body balance.

 

*         Medulla Oblongata

It joints brain and the spinal cord. Functions like digestion, blood pressure, breathing, etc. is controlled by this organ.

 

 

 

*           Nerve

Spinal cord is a mass of nerves running down the middle of the backbone. A fine network of nerves connects the brain and the spinal cord to every part of our body.

They carry messages to and from the brain to the body part. Nerves present in our body are of two main types. The sensory nerves, which carries messages from the sense organ to the spinal cord or the brain. Motor nerves which carries messages from the brain or the spinal cord to various parts of the body. 90% of full weight of the brain is achieved at the age of 5 years.

 

 

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      Human nervous system consists of

(a) Brain

(b) Spinal cord

(c) Nerves

(d) All of these                                 

(e) None of the above

 

Answer: (d)

 

 

      Nerves which carry the messages from the sense organs to the spinal cord or brain are

(a) Motor nerves                                            

(b) Sensory nerves

(c) Both type of nerves carry messages to the brain

(d) All of the above                                        

(e) None of the above

 

Answer: (b)

 

 

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The stomach's digestive acids are strong enough to dissolve zinc. Fortunately for us, the cells in the stomach lining renew so quickly that the acids don't have time to dissolve it.

Each finger and toenail takes six months to grow from base to tip.

The lungs contain over 300,000 million capillaries (tiny blood vessels). If they were laid end to end, they would stretch 2400 km.

 

 

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Nutrients: The component of food which is necessary for our body.

Sense Organ: The organs which helps us to sense the outside world.

Digestion: The process of breaking down of the complex food materials into simple form.

Respiration: It is a process of releasing energy from the food.

Circulatory system: It transport oxygen and nutrients to all parts of the body and bring back carbon dioxide and waste from the body.

Excretory system: Removes the waste materials from the body.

Nervous system: Coordinates between the body parts and brain.

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