Body Movement Class 6 Notes Science Chapter 5

Ever wondered how you can bend, stretch, or even wiggle your fingers? Our bones, muscles, and joints work together like a team to make all our movements possible. Muscles, bones, and joints are essential for movement in the human body. Let's discover how our body moves!

Human Body and its Movements

Movements: A change in the position of any object is called movement. Many movements take place in our bodies and also in other organisms bodies.

Here are examples of movements: 

• Bending of Elbow and Knee
• Turning of Head
• Moving Arms in a Circle
• Bending Fingers
• Walking or Running
• Swinging the Leg

Joints

• Joints are places in our body where two parts meet, like the elbow, shoulder, or neck.
• Function of Joints: They allow us to bend and move our body parts. Without joints, we wouldn’t be able to move our body parts at all.
• Bones and Joints: Bones are hard structures in our body, and they can’t bend. Joints are where these bones come together, allowing movement.
  For example, the elbow is where the upper arm and forearm bones meet, and it lets us bend our arm. 
  Joint

Ball and Socket Joints

• In this joint, the rounded end of one bone fits into the cavity (hollow space) of another bone. 
• It permits movement in all directions.
• The joint between the shoulder and the upper arm is an example of a ball and socket joint.
• Similarly, the joint between the thigh and hip is an example of a ball and socket joint.
  Shoulder Joint

Pivotal Joint

• Structure: In a pivotal joint, a cylindrical bone rotates within a ring-shaped bone or structure.
• Movement: This joint allows movement in a limited range—mainly rotation. For example, it lets us bend our head forward and backward and turn it from side to side.
• Example: The joint where our neck connects to the head is a pivotal joint. It allows these specific head movements but does not enable a complete circle of rotation like a ball-and-socket joint.

Pivotal Joint

Hinge Joints

• Structure: A hinge joint allows movement in one direction, similar to the way a door moves on its hinges.
• Movement: This joint permits a back-and-forth or swinging motion. It does not allow rotational movement like a ball-and-socket joint.
• Example: The elbow is an example of a hinge joint. It allows your arm to move forward and backward but not in a circular motion.
  Knee Hinge Koint

Fixed Joints

• Structure: Fixed joints are immovable joints where bones are joined tightly together, and no movement occurs at these joints.
• Example: The joints between the bones in our head, such as where the upper jaw meets the rest of the skull, are fixed joints.
• Movement: While the lower jaw can move to open and close the mouth, the upper jaw remains fixed and does not move.

X-ray images show the shapes of bones and help doctors detect injuries or conditions in bones.

"Gait of Animals"

Different animals have different organs for locomotion.

Earthworm

Snail

Cockroach

• Cockroaches can walk, climb, and fly.
• They have three pairs of legs used for walking.
• Their body is covered with a hard outer skeleton made of plates joined together, allowing movement.
• They have two pairs of wings attached behind the head.
  Cockroach
• Distinct muscles near the legs facilitate walking.
• Body muscles control the wings for flying.

Birds

• Birds can fly in the air, walk on the ground, and some, like ducks and swans, can also swim in water.
• Their bodies are well-suited for flight with hollow and light bones.
• Hind limb bones are adapted for walking and perching.

Bird Skeleton

• Forelimb bones are modified into wings.
• Shoulder bones are strong to support flight.
• Breastbones are modified to hold flight muscles used to move the wings up and down.

Fish

Streamlined Shape: Fish have a streamlined body shape, similar to a boat, which helps them move efficiently through water. The body is tapered at both ends, making it easier for water to flow around it.

Swimming Mechanism:

• The fish's muscles cause the body to curve from side to side. The front part of the body curves to one side, while the tail swings to the opposite side, forming a curve.
• This movement creates a series of jerks that push the fish forward. The fish then quickly reverses the curve to continue swimming.
  Fish

Fins and Balance:

• Tail Fins: The tail fins play a crucial role in propelling the fish forward.
• Other Fins: Additional fins help maintain balance and direction while swimming.

Flippers for Divers: Underwater divers use fin-like flippers on their feet, which function similarly to fish fins, aiding in easier movement through water.

How do Snakes Move?

Snakes have a long backbone and numerous thin muscles that are interconnected along the length of their body. These muscles are also connected to the backbone, ribs, and skin.

Snake

Movement Mechanism:

• The snake's body curves into many loops. Each loop presses against the ground to push the snake forward.
• The continuous looping motion allows the snake to move quickly, though not in a straight line.