Study Notes: Body Movements

Grade VI Science Study Notes

Chapter: Body Movements

1. Introduction

Movement is one of the most important characteristics of living organisms. Animals move from one place to another to search for food, escape from enemies, find shelter, and reproduce. Even when we are sitting or sleeping, many parts of our body continue to move, such as our heart, lungs, and digestive system.

2. Why Do We Move?

Living organisms move for different reasons.

Humans move to:

  • Walk and run
  • Work and play
  • Exercise
  • Communicate
  • Protect themselves
  • Search for food and water

Animals move to:

  • Find food
  • Escape from enemies
  • Build nests
  • Find mates
  • Protect their young
  • Migrate to suitable places

3. How Does Our Body Move?

Our body moves with the help of three main parts working together:

  • Bones – form the framework of the body.
  • Muscles – pull the bones to produce movement.
  • Joints – connect bones and allow movement.

Muscles can only pull, not push. They work in pairs. When one muscle contracts, the other relaxes.

4. Skeletal System

The skeletal system is the framework of bones in our body.

An adult human has 206 bones.

The skeleton includes:

  • Skull
  • Backbone (vertebral column)
  • Rib cage
  • Shoulder bones
  • Hip bones
  • Bones of arms
  • Bones of legs

5. Functions of the Skeletal System

The skeletal system performs many important functions.

It:

  • Gives shape to the body.
  • Supports the body.
  • Protects internal organs.
  • Helps in movement.
  • Produces blood cells in bone marrow.
  • Stores minerals such as calcium and phosphorus.

Examples

  • Skull protects the brain.
  • Rib cage protects the heart and lungs.
  • Backbone supports the body and protects the spinal cord.

6. Joints

A joint is the place where two or more bones meet.

Joints allow different types of movements.

Types of Joints

A. Ball and Socket Joint

  • Allows movement in all directions.
  • Found in the shoulder and hip.

Examples:

  • Rotating the arm
  • Swinging the leg

B. Hinge Joint

Moves in one direction only.

Found in:

  • Elbow
  • Knee
  • Fingers
  • Toes

Examples:

  • Bending the elbow
  • Folding the knee

C. Pivot Joint

Allows the head to turn from side to side.

Found between the skull and the first vertebra.

Example:

  • Shaking the head to say "No".

D. Fixed Joint

Does not allow movement.

Found in:

  • Skull

The bones of the skull are tightly joined to protect the brain.

E. Gliding Joint

Allows limited sliding movement.

Found in:

  • Wrist
  • Ankle

7. How Do Bones Move?

Bones cannot move by themselves.

Movement occurs when:

  1. Muscles contract.
  2. Muscles pull the bones.
  3. Bones move at the joints.

Example

When you bend your arm:

  • The biceps muscle contracts.
  • The triceps muscle relaxes.
  • The forearm moves upward.

When you straighten your arm:

  • The triceps contracts.
  • The biceps relaxes.

8. Can We See Bones?

Normally, bones cannot be seen because they are covered by muscles and skin.

Doctors use X-rays to see bones inside the body.

X-rays help to:

  • Detect fractures
  • Find broken bones
  • Diagnose bone diseases

9. How Do Other Animals Move?

Different animals have different body structures. Therefore, they move in different ways.

A. Earthworm

Structure

  • Long, soft body.
  • No legs or bones.
  • Body divided into many ring-like segments.

Movement

  • Moves by contracting and expanding its muscles.
  • Tiny bristles (setae) help grip the soil.
  • Creeps forward by stretching and shortening its body.

B. Snail

Structure

  • Soft body.
  • Hard shell on its back.

Movement

  • Moves using a strong muscular foot.
  • Secretes mucus (slime), which reduces friction.
  • Glides slowly on surfaces.

C. Fish

Structure

  • Streamlined body.
  • Covered with scales.
  • Has fins and a tail.

Movement

  • Swims by moving its tail from side to side.
  • Fins help in balancing, steering, and stopping.

D. Cockroach

Structure

  • Six legs.
  • Two pairs of wings.
  • Hard outer covering (exoskeleton).

Movement

  • Walks and runs using six legs.
  • Can also fly short distances using wings.

E. Birds

Structure

  • Light, hollow bones.
  • Strong chest muscles.
  • Wings covered with feathers.

Movement

  • Fly using wings.
  • Walk and hop using legs.
  • Tail helps in balancing and changing direction.

F. Snake

Structure

  • Long body.
  • Flexible backbone with many ribs.
  • No legs.

Movement

  • Slithers by making S-shaped curves.
  • Strong muscles push against the ground to move forward.

Comparison of Animal Movements

Animal

Organ Used for Movement

Type of Movement

Earthworm

Body muscles and setae

Creeping

Snail

Muscular foot

Gliding

Fish

Tail and fins

Swimming

Cockroach

Legs and wings

Walking, Running, Flying

Bird

Wings and legs

Flying, Walking

Snake

Body muscles and ribs

Slithering

Key Differences

Bones vs Muscles

Bones

Muscles

Hard

Soft

Give support

Help in movement

Cannot contract

Can contract and relax

Form skeleton

Attached to bones

Fixed Joint vs Movable Joint

Fixed Joint

Movable Joint

No movement

Allows movement

Skull

Shoulder, Knee, Elbow

Keywords

  • Movement
  • Skeleton
  • Skeletal System
  • Bone
  • Muscle
  • Joint
  • Ball and Socket Joint
  • Hinge Joint
  • Pivot Joint
  • Fixed Joint
  • Gliding Joint
  • Backbone
  • Rib Cage
  • Skull
  • Vertebral Column
  • X-ray
  • Earthworm
  • Snail
  • Fish
  • Cockroach
  • Bird
  • Snake

Quick Revision

  • The skeletal system forms the body's framework.
  • An adult human has 206 bones.
  • Bones, muscles, and joints work together for movement.
  • Muscles work in pairs.
  • Ball and socket joints allow movement in all directions.
  • Hinge joints allow movement in one direction.
  • Pivot joints help us turn our head.
  • Fixed joints do not move.
  • Gliding joints allow slight movement.
  • X-rays help doctors see bones.
  • Different animals move using different body parts.

Exam Practice

Very Short Answer Questions

  1. Why do living organisms move?
  2. What is the skeletal system?
  3. How many bones does an adult human have?
  4. What is a joint?
  5. Name the five types of joints.
  6. Which joint is found in the shoulder?
  7. Which joint is found in the elbow?
  8. Which joint is found in the skull?
  9. Which joint helps us turn our head?
  10. Which instrument is used to see bones inside the body?
  11. How does an earthworm move?
  12. Which body part helps a snail move?
  13. Which organs help a fish swim?
  14. How many legs does a cockroach have?
  15. How does a snake move?

Short Answer Questions

  1. Explain the functions of the skeletal system.
  2. Describe the different types of joints with examples.
  3. Explain how muscles help bones move.
  4. Why are X-rays useful?
  5. Describe the movement of an earthworm, snail, fish, cockroach, bird, and snake.

Long Answer Questions

  1. Explain the skeletal system and its functions with suitable examples.
  2. Describe the different types of joints and their locations in the human body.
  3. Explain how different animals move according to their body structure.