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The Human Body - The Skeletal System

Grade 3ICSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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The skeletal system is the internal framework of the body, consisting of 206206 bones in an adult human.

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A newborn baby has more bones (approximately 300300) which eventually fuse together as they grow.

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The Skull is the hard structure that protects the brain and gives shape to the face.

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The Ribcage consists of 1212 pairs of curved bones that protect delicate organs like the heart and lungs.

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The Backbone (also called the Spine or Vertebral Column) is made up of 3333 small bones called vertebrae, allowing us to bend and twist.

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Joints are places where two or more bones meet (e.g., elbow, knee), enabling movement of body parts.

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Bones are made of minerals, primarily CalciumCalcium and PhosphorusPhosphorus, which make them hard and strong.

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The main functions of the skeletal system are: Providing shape and support, protecting internal organs, and assisting in movement.

📐Formulae

Total Bones (Adult)=206Total\ Bones\ (Adult) = 206

Total Bones (Infant)≈300Total\ Bones\ (Infant) \approx 300

Calcium+Vitamin D→Strong BonesCalcium + Vitamin\ D \rightarrow Strong\ Bones

12 pairs of ribs=24 bones12\ pairs\ of\ ribs = 24\ bones

💡Examples

Problem 1:

Identify the part of the skeletal system that protects the brain.

Solution:

The Skull.

Explanation:

The skull is a bony structure that acts like a helmet to shield the brain from injuries.

Problem 2:

Why can we bend our back even though bones are hard?

Solution:

Because of the Backbone which is made of 3333 small vertebrae.

Explanation:

The backbone is not one single long bone; it is a chain of small bones called vertebrae that allow flexibility and movement.

Problem 3:

What would happen if the human body had no bones?

Solution:

The body would be a soft, shapeless mass.

Explanation:

The skeletal system provides the FrameFrame and SupportSupport necessary to keep the body upright and maintain its shape.