The Nervous System and Sense Organs

Basic Science E-Note

Class: Grade 9

Topic: The Nervous System and Sense Organs

1. Meaning of the Nervous System

• The nervous system is the control and communication system of the body.
• It helps us think, feel, move, and respond quickly to what happens around us.
• Example: when you touch something hot, your nervous system makes you pull your hand away immediately.

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2. Central and Peripheral Nervous System

The nervous system has two main parts:

(a) Central Nervous System (CNS)

• Made up of the brain and spinal cord.
• Functions:
• Controls thinking, memory, emotions.
• Directs body movement and coordination.

(b) Peripheral Nervous System (PNS)

• Made up of all the nerves outside the brain and spinal cord.
• Functions:
• Carries messages from the CNS to the rest of the body.
• Helps us respond to changes in the environment.

Example:
When you hear the school bell:

• Ear (sense organ) detects the sound.
• Message goes to the CNS (brain).
• The PNS carries the instruction to your legs to stand up or move.

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3. The Sense Organs

There are five main sense organs:

1. Eye – for seeing (sight).
2. Ear – for hearing (sound).
3. Nose – for smelling.
4. Tongue – for tasting.
5. Skin – for touching (feeling).

Importance of Sense Organs:

• They help us enjoy life (e.g., taste of food, sound of music).
• They keep us safe (e.g., seeing danger, feeling pain).
• Without them, life would be difficult (e.g., blindness, deafness).

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ASSIGNMENT

1. What is the function of the nervous system?
2. Mention the two parts of the nervous system and state one function of each.
3. List the five sense organs and their uses.

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Multiple Choice Questions

1. The nervous system is mainly responsible for __________.
   A. Digestion and excretion
   B. Control and communication in the body
   C. Circulation of blood
   D. Growth and reproduction
2. Which of the following is not a part of the Central Nervous System (CNS)?
   A. Brain
   B. Spinal cord
   C. Nerves in the hand
   D. Cerebrum
3. The part of the nervous system that carries messages between the CNS and the rest of the body is called the __________.
   A. Central Nervous System
   B. Peripheral Nervous System
   C. Circulatory System
   D. Digestive System
4. The brain and spinal cord work together to __________.
   A. Control body movement and coordination
   B. Pump blood throughout the body
   C. Help in digestion
   D. Store excess food
5. When you touch something hot and pull your hand away immediately, it shows the work of the __________.
   A. Skeletal system
   B. Digestive system
   C. Nervous system
   D. Respiratory system
6. Which of the following is a sense organ?
   A. Heart
   B. Eye
   C. Kidney
   D. Liver
7. The sense organ used for hearing is the __________.
   A. Eye
   B. Tongue
   C. Ear
   D. Nose
8. Which sense organ helps us to detect taste?
   A. Eye
   B. Skin
   C. Tongue
   D. Nose
9. The skin helps us mainly to __________.
   A. See things clearly
   B. Feel heat, cold, and pain
   C. Taste different foods
   D. Smell pleasant odors
10. Why are the sense organs important to humans?
    A. They help us to enjoy and stay safe in our environment
    B. They help us to grow taller
    C. They help us to digest food
    D. They help us to breathe

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Answers

1. B – Control and communication in the body
2. C – Nerves in the hand
3. B – Peripheral Nervous System
4. A – Control body movement and coordination
5. C – Nervous system
6. B – Eye
7. C – Ear
8. C – Tongue
9. B – Feel heat, cold, and pain
10. A – They help us to enjoy and stay safe in our environment

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