3rd Class Science Our Body Nervous System

Nervous System

Category : 3rd Class

*     Nervous System


Every day our body performs a lot of functions. Brain is at the center of all the activities. Brain only tells us what to do or what not to do. For example, in the process of walking brain just order the related organ to move. Muscles which are involved in waking get active and perform walking.




*       Coordination and Cooperation between Brain and Body

Our eyes see a rose flower. This message reaches brain through a network of cells called nerves. Brain interprets the information and recognise that it is a rose flower. The nerves act like messenger. Spinal cord connects all the parts of the body to the brain. Skull protects brain and backbone protects spinal cord from injury. The brain, spinal cord and nerves constitutes nervous system.

When finger touch the hot plate, receptor receives the information and send it to brain through nerves. Brain analyze the situation and order the related muscles to remove the finger. This all happens in fraction of a second. This is how body performs function under the guidance of the brain.

 Stimulus --> Message --> Nerves --> Brain --> Nerves --> Fingers to remove


*         Nervous Problems




Headache is common in people which are generally not very serious. Migraine is a severe headache that can be dangerous. Development of tumour in the brain is a very dangerous problems, which are removed surgically.


*         How to Prevent the Nervous Problems

We should protect our brain from any injury. Wearing helmet is a protective device while riding a bike.





      Which one of the following organs sends message to the brain from the receptor site.

(a) Heart

(b) Lungs

(c) Skin

(d) Nerves

(e) Finger


Answer: (d)


Nerves receives messages from the receptor as an electrical impulses and carries it to the brain. Therefore, option (d) is correct and rest of the options is incorrect.



     Consider the following statements:

Statement 1: Brain is a part of nervous system

Statement 2: Brain is a part of muscular system

Which one of the following is correct about the above statements?

(a) Statement 1 is true and 2 is false

(b) Statement 1 is false and 2 is true

(c) Both statements are false

(d) Both statements are true

(e) None of these


Answer: (a)


Brain is a part of nervous system. Therefore, option (a) is correct and rest of the options is incorrect.



*     Circulatory System




Blood is an important part of the body, because it contains vital nutrients and oxygen to burn food and produce energy for the body to live. Blood has to reach to all the cells of the body. This work is performed by the heart. Heart behaves like pumping organ. It pumps blood to all the parts of the body through a network of blood vessels, which is actually thin tube like structure. The heart, the blood and the blood vessels constitutes circulatory system. Heart is made up of muscles only and works non stop. To do any heavy work or exercise body requires more energy. Therefore, heart pumps the blood faster to meet the demand. That is why when we run, our heart beats gets faster. When we rest, our heart beats about 72 times a minute.

*        Heart Problems

Fainting occurs when heart can't pump enough blood to the brain. Heart attack happens when blood vessels that supply the blood to the heart are blocked resulting in less supply of oxygen to the heart.


*         How to keep Heart and Blood Healthy

Eat less fat and salt in diet

Avoid smoking

Exercise regularly

Live stress free life





     Riya is running fast to overtake her brother Ayush who is 100 meter ahead of her. Her heart beat:

(a) Would be slower

(b) Would be faster

(c) Would beat 72 times a minute

(d) None of these

(e) All of these


Answer: (b)


While running, our body requires more energy and to meet that demand heart beats gets faster. Therefore, option (b) is correct and rest of the options is incorrect



   Which one of the following organs can be compared with the pump?

(a) Heart

(b) Lungs

(c) Kidney

(d) Brain

(e) None of these


Answer: (a)


Heart is an organ which pumps blood to all the parts of the body. Therefore, option (a) is correct and rest of the options is incorrect.  



*     Excretory System

Kidney filters excess water and ammonia from the blood and make the blood pure. These unwanted substances are urine, which is excreted or removed outside the body through the urinary bladder. Similarly our skin removes unwanted substance from the body in the form of sweat. Hence the system which cleans our body is called as excretory system. Kidney, urinary bladder urethra etc. are excretory organs.


*       Excretory Problem

Kidney fails and the blood is not filtered properly. Patients are kept on dialysis machines to do blood filtering work.


*       How to Prevent the Excretory Problem

Eat healthy diet and do regular exercise to keep fit. Drink plenty of water each day.


*     Reproductive System

Living organism produces offspring of its own kind to increase its number and to maintain the balance in the nature. Reproductive system performs the process of reproduction. Reproductive system is very essential for new life.  





     Which one of the following systems is responsible for producing off springs of its own kind?

(a) Excretory system

(b) Circulatory system

(c) Muscular system

(d) Reproductive system

(e) Nervous system


Answer: (d)


Reproductive system produces babies which develop into an adult. Therefore, option (d) is correct and rest of the options is incorrect.



     Excretory system is called as cleaning system of the body because:

(a) Excretory system sweeps the body

(b) Excretory system makes the body beautiful

(c) Excretory system removes wastes, generated in the body, to outside

(d) Excretory system produces babies

(e) None of these


Answer: (c)


Kidney filters blood, skin removes waste salt from the body along with water, hence it is called as cleaning system. Therefore, option (c) is correct and rest of the options is incorrect..

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