Skeletal System

  • Provides shape and strength to the body
  • Protects internal organs
  • 206 bones in an adult human body
  • Major bones: Skull, Ribcage, Backbone, Limbs (arms and legs)


Major Bones and Functions

  • Skull: Protects the brain, 22 bones
  • Ribcage: Protects heart and lungs, 12 pairs of ribs
  • Backbone (Vertebral column): Main axis, allows bending and twisting, 33 small bones
  • Jawbone: Largest and strongest bone in face, helps in biting and chewing


Importance of Bones

  • Shape and support: Give shape and strength to the body
  • Protection: Protect soft internal organs like brain, heart, and lungs


Limbs

  • Upper limbs (arms): Humerus, radius, ulna
  • Lower limbs (legs): Femur (thigh bone), connected by girdles (shoulder and hip)


Joints

  • Types: Movable and Immovable
  • Function: Allow movement, protect bones from wear and tear
  • Examples of movable joints: Knees, elbows, hips
  • Examples of immovable joints: Skull joints (except lower jaw)

Exercise

A. Tick (✔) the correct option.

1. The framework of bones that gives support to our body is called.............

i. muscles

ii. skeleton √

iii. ribcage

2. The bony structure that encloses heart and lungs is .................

i. backbone

ii. ribcage √

iii. blood

3. Red blood cells are produced in the ....................

i. muscles

ii. bone marrow √

iii. lower joint

4. Vertebral column is made up of ...................... small bones.

i. 22

ii. 33 √

iii. 11

5. Both smooth an ............. muscles are involuntary muscles

i. rough

ii. cardiac √

iii. skeletal


C. Write ‘T’ for True and ‘F’ for False.

1. 14 flat bones joined together protect the brain. - T

2. The lower jaw enables us to eat and talk. - T

3. Ribcage encloses liver and kidneys. - F (Ribcage protects heart and lungs)

4. Joints of the bones are held together by strong tissue called ligaments. - T

5. Muscles are attached to bones through tendons. - T


D. Match the following.

1. Smooth muscles - iii. stomach and intestines

2. Hinge joint - iv. elbows and fingers

3. Bone marrow - v. blood cells

4. Ball and socket joint - i. hip and shoulder

5. Gliding joint - ii. wrist and ankle


E. Name the following.

1. The frame work of all bones - Skeleton

2. The last two pairs of ribs that are joined to the backbone - Floating ribs

3. The longest bone in our body - Femur

4. It protects the bones from wear and tear Cartilage

5. The muscles whose movements can be controlled by us - Voluntary muscles