🎯 Learning Objectives
- Know the main internal organs and their functions: brain, heart, lungs, and stomach.
- Understand the skeletal system -- bones give shape and protect organs.
- Understand the muscular system -- muscles help the body move.
- Learn the importance of regular exercise and adequate sleep for a healthy body.
📖 Let Us Begin!
Your body is like a wonderful machine. On the outside, you can see your skin, hands, legs, and face. But inside, there are many important parts called organs that work together to keep you alive and healthy. Just like a car needs an engine, fuel, and wheels to run, your body needs the brain to think, the heart to pump blood, the lungs to breathe, and the stomach to digest food.
Internal Organs and Their Functions
| Organ | Location | Main Function |
|---|
| Brain | Inside the skull (head) | Controls thinking, memory, feelings, and all body actions |
| Heart | In the chest, slightly to the left | Pumps blood to all parts of the body |
| Lungs | In the chest, on both sides of the heart | Help us breathe -- take in oxygen and release carbon dioxide |
| Stomach | In the upper part of the abdomen | Digests the food we eat and breaks it into smaller parts |
Example: When Ananya runs during PT class, her brain tells her legs to move. Her heart beats faster. Her lungs breathe in more air. The food she ate gives her energy -- her stomach had already digested it.
Think: Place your hand on the left side of your chest. Can you feel your heart beating? It beats about 70-100 times every minute.
[Image: A labelled diagram of the human body showing major organs — brain, lungs, heart, stomach, liver, kidneys, intestines. Title: "Major Organs of the Human Body"]
The Skeletal System
The skeletal system is the framework of bones inside your body. An adult has 206 bones. Bones do three important jobs:
- Give shape -- Bones give your body its shape.
- Protect organs -- The skull protects the brain. The rib cage protects the heart and lungs.
- Help in movement -- Bones work with muscles and joints to help you walk, run, and bend.
The place where two bones meet is called a joint. Your elbow, knee, and shoulder are joints.
Think: Touch the top of your head, your elbow, and your knee. You can feel the hard bones under the skin.
The Muscular System
Your body has more than 600 muscles. Muscles are attached to bones and help the body move. When you lift your school bag, the muscles in your arm pull the bones to make your arm bend.
Some muscles work automatically. The heart is a muscle that keeps pumping blood day and night. The muscles in your stomach help digest food without you thinking about it.
Example: When Ravi kicks a football, the muscles in his leg contract to push his leg forward. When he smiles, the muscles in his face move to form the smile.
Importance of Exercise and Sleep
- Exercise makes muscles stronger, keeps the heart healthy, and helps bones grow. Playing kabaddi, running, or cycling are great exercise.
- Sleep gives your body time to rest and repair. Children aged 9-10 need 8 to 10 hours of sleep every night.
Think: What happens when you do not sleep well? You feel tired, cannot concentrate, and may fall sick more easily.
📝 Key Words
| Word | Meaning |
|---|
| Organ | A part of the body that does a special job (e.g., heart, brain) |
| Skeleton | The framework of all the bones in the body |
| Joint | The place where two bones meet, allowing movement |
| Muscle | A body part that contracts and relaxes to produce movement |
| Digest | To break down food into smaller parts the body can use |
⭐ Key Points to Remember
- The brain controls thinking and all body actions. The heart pumps blood. The lungs help us breathe. The stomach digests food.
- The human body has 206 bones. Bones give shape, protect organs, and help in movement.
- The body has more than 600 muscles. Muscles help us move by pulling on bones.
- Some muscles (like the heart) work automatically without us thinking about them.
- Regular exercise and 8-10 hours of sleep every night keep the body healthy.
A. Fill in the Blanks
1. The controls thinking, memory, and all body actions.
2. The heart pumps to all parts of the body.
3. We have bones in our body.
4. The place where two bones meet is called a .
5. Children need to hours of sleep every night.
B. Multiple Choice Questions
1. Which organ is protected by the rib cage?
(a) Brain(b) Stomach(c) Heart and Lungs(d) Kidneys
2. How many bones does an adult human body have?
(a) 106(b) 206(c) 306(d) 600
3. Which of the following is a muscle that works automatically?
(a) Arm muscle(b) Leg muscle(c) Heart(d) Finger muscle
C. Short Answer Questions
1. Name two things that bones do for our body.
2. Why is exercise important for children?
3. What happens to your heart when you run fast? Why?
🎨 Fun Activity -- My Body Diary
For one day, observe how your body works. Fill in the table below.
| Activity | Which Organ / Body Part Helped? |
|---|
| Eating breakfast | |
| Running to school | |
| Solving a maths problem | |
| Breathing during yoga | |
| Lifting your school bag | |