Body Movements
Overview
We walk, run, write — but how does all this happen? It is the work of bones (skeleton) and muscles. In this chapter, we will read the story of the joints in our skeleton and the ways in which animals move.
Typed Notes
Skeleton — the framework of the body
The skeleton is the framework of the body — a frame made of bones that holds everything inside. An adult human has 206 bones (a baby is born with about 300 bones, and some of them fuse together over time). The longest bone is the thigh bone (femur); the smallest bone is in the ear (stapes). The skeleton: (1) gives us shape and keeps us upright, (2) protects our organs (the skull protects the brain, the ribs protect the heart and lungs), (3) produces blood (inside the bones), (4) works together with muscles to allow us to move.
Joints — the movable meeting points
The place where two bones meet is called a joint, and it is from here that movement comes: (1) Ball and socket — the rounded head of one bone fits into the cup-shaped socket of another: shoulder, hip — it can rotate in every direction. (2) Hinge — like a door hinge: it bends in only one direction — elbow, knee, fingers. (3) Pivot — one bone rotates over another — the neck (turning the head left and right). (4) Fixed — these never move: the bones of the skull (to protect the brain). Every joint has its own role — that is why we can move in so many different directions.
Muscles — the pullers
Bones do not move on their own — muscles pull them. A muscle does only one thing: it contracts. That is why every movement needs a pair of muscles: one contracts and pulls the bone in one direction, and the other pulls it back. For example, the bicep and tricep — they bend and straighten the elbow. A muscle is connected to the bone by a cord called a tendon. That is why daily body movement and eating protein are important.
How animals move
Every animal moves according to its habitat: Earthworm — its long body has muscles that alternately contract and expand, and small bristles grip the ground — giving it a snake-like movement. Snail — it has a muscular foot under its belly — it glides along slowly. Cockroach — it has 6 legs (each with joints and muscles) and also flies using its wings. Fish — its streamlined body (water flows past it easily) + fins (for balance and direction) + tail (for speed). Bird — light (hollow) bones + wings — to fly through the air. Every animal has its own design — suited to its home environment.
Key Concepts
Revision ke liye ek nazar — exam se pehle yahi padhna hai.
- 01Skeleton: The framework of the body — a frame made of bones. An adult human has 206 bones; the longest bone is the thigh bone (femur).
- 02Joints: The place where two bones meet. Types: Ball and socket (shoulder, hip), Hinge (elbow, knee), Pivot (neck), Fixed (skull).
- 03Muscles: They pull the bones and make them move — there is a muscle for every movement; a muscle can only contract.
- 04How animals move: Earthworm — muscles + bristles; Snail — muscular foot; Cockroach — 6 legs + wings; Fish — streamlined body + fins; Bird — light bones + wings.
- 05For strong bones: calcium (milk and curd) and Vitamin D (sunlight) are necessary — otherwise bones become weak (fracture).
Questions & Solutions
Pehle khud try karo — phir solution kholo. Yahi tariqa topper banata hai.
What is the difference between a ball and socket joint and a hinge joint? Give examples.
Which joint allows the neck to rotate?
How does a fish swim easily in water?
How does an earthworm move without legs?
What does the skeleton give us? Write four functions.
What should we do to keep our bones strong?
The skeleton is a framework of 206 bones. Joints: ball and socket (shoulder), hinge (elbow and knee), pivot (neck), fixed (skull). Muscles pull and create movement. Every animal moves in its own way — the earthworm uses muscles, the snail uses its foot, the fish uses fins, and the bird uses wings.
Chapter-end quiz
4 MCQsOption tap karo — turant pata chalega sahi ya galat, explanation ke saath.
Q1.How many bones does an adult human have?
Q2.Which type of joint is the elbow?
Q3.How does a snail move?
Q4.What helps a fish swim?
Mark karo — dashboard par progress dikhega.