NCERT Class 6 Science Chapter 8: Body Movements YouTube Lecture Handouts

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Image of Animal Body Parts

Image of Animal Body Parts

Image of Animal Body Parts

  • Many movements like walk, run, jump, creep, crawl, swim

  • Why we bend or rotate? Due to Joints – neck, elbow or shoulder

  • We can bend at those points where bones meet

Image of Types of Joints

Image of Types of Joints

Image of Types of Joints

Image of Types of Synovial Joints

Image of Types of Synovial Joints

Image of Types of Synovial Joints

Ball & Socket Joints

  • Allows movement in all directions

  • Shoulder and hip joint

Image of Ball and Socket Joints

Image of Ball and Socket Joints

Image of Ball and Socket Joints

Pivotal Joint

  • Neck is joint to our head

  • Allows forward and backward and right and left movement

  • In a pivotal joint a cylindrical bone rotates in a ring.

Hinge Joints

  • Elbow & knee joint

  • Allows back and forth movement

Image of Hinge Joints

Image of Hinge Joints

Image of Hinge Joints

Fixed Joints

  • Bones cannot move at the joints

  • Upper jaw or mandible

Skeleton

  • Framework of bones – Skeleton – gives frame and shape and helps in movement, protects inner organs

  • X-ray images

Image of X-ray

Image of X-Ray

Image of X-ray

  • Ribs are bent and join the chest bone to form a box called rib cage

  • Towards the back we have backbone

  • Pelvic bones lie below the stomach – where you sit

  • Shoulder bones

  • Certain bones in the lowermost of the vertebral column are separate bones in the beginning. Slowly, some of them fuse together and appear as one bone. (Child has more bones than adult)

Cartilages

  • Not as hard as bones

  • Can bent

  • Ear – lower lobe part is soft as compared to upper

  • Skeleton includes bones, joints and cartilage

Image of Cross Section of Joint

Image of Cross Section of Joint

Image of Cross Section of Joint

Muscles

  • Contracted when walk or run – becomes short, stiff and thicker and pulls the bone

  • Muscles work in pairs – one is contracted, other is relaxed

  • Muscle can only pull and not push

  • Muscle must work together to move a bone

Gait (Movement) of Animals Book by Aristotle

  • Some fishes don’t have bones, but they do have certain kind of structures made up of slightly tough material – cartilage. Some others, like whales, have a skeleton made of huge, strong bones.

  • Cockroach, butterfly and birds, all the three have wings. But their wings are not similar.

Earthworm

  • Earthworm has no bones and rings joint end to end

  • Muscles help extend and shorten the body – it fixes front end and releases rear end

  • Then shortens body and pulls rear end forward

  • Large number of tiny bristles (hair like structures) projecting out. The bristles are connected with muscles

  • Earthworm eats through the soil & throws away undigested part of material that it eats

Snail

  • Outer skeleton of snail is shell (single unit to be dragged along)

  • Foot is made of strong muscles and is thick structure and helps to move

Cockroach

  • Hard outer skeleton of chitin

  • 2 pairs of wings joint to breast muscle – governs flight

Birds

  • Hollow and light bones to fly

  • Hind limb bones are meant for walking and perching

  • Bony part of forelimb is modified as wings

  • Breastbones modified to hold the muscle of flight for movement of wings up and down

Fishes

  • Head and tail are smaller than middle part and body tapers at both ends – streamlined

  • Allows fish to move in water

  • Skeleton has strong muscles

  • Direction is governed by fins of tail

  • Other fins – balance the body

  • Divers wear flippers on feet to move easily

Snakes

  • Long backbone with thin muscles

  • They interconnect backbone, ribs and skin

  • Body curves into loops and pushes it forward by pressing against the ground

  • Since its long body makes many loops and each loop gives it this push, the snake moves forward very fast and not in a straight-line