Grade 5 (age 10-11)

Human Body Systems

Your body is a team of organs that each do a special job. The digestive system breaks food down for nutrients, the respiratory system takes in oxygen, and the heart pumps blood to carry both around the body. Bones and muscles give you shape and let you move. Switch between the three organ systems here to see what each one does.

Body Organ Systems

System0

🫀 Digestive System

①Mouth chews food into pieces

②Food goes down the esophagus to the stomach

③Stomach dissolves food with digestive juices

④Small intestine absorbs nutrients

⑤Large intestine absorbs water and removes waste

Comparing Systems

System Comparison

ChartDigestive · Respiratory · Circulatory

Category	Digestive	Respiratory	Circulatory
Function	Break down & absorb food	Take in oxygen	Send blood through body
Main Organs	Mouth, stomach, sm. intestine	Nose, trachea, lungs	Heart, blood vessels
Analogy	Food factory	Air purifier	Delivery service
Output	Nutrient absorption	Oxygen supply	Oxygen + nutrients

Bones & Muscles

🦴 Roles of Bones & Muscles

①Bones: support the body and maintain shape

②Bones: protect vital organs like brain, heart

③Muscles: attach to bones to move the body

④When muscles contract → bones move

⑤~206 bones and ~600 muscles

Summary

Digestive Path

Mouth → Esophagus → Stomach → Small Intestine → Large Intestine

Food is broken down and nutrients are absorbed

Respiration & Circulation

Nose → Trachea → Lungs (O₂) → Heart → Vessels → Body

Oxygen is taken in, carried by blood throughout the body

🎯 Key Points

①Digestive: breaks down food and absorbs nutrients

②Respiratory: takes in oxygen, exhales CO₂

③Circulatory: delivers oxygen & nutrients via blood

④Bones: support + protect; Muscles: movement

⑤All systems must cooperate for a healthy life

Examples and Unit Test

Example 1

Which digestive organ absorbs nutrients from food, and which respiratory organ takes in oxygen?

Food is digested through the mouth → esophagus → stomach → small intestine → large intestine.

Nutrients are absorbed in the small intestine, and oxygen is taken in by the lungs.

▸ Nutrient absorption: small intestine / oxygen intake: lungs

Digestion absorbs nutrients in the small intestine; respiration takes in oxygen at the lungs.

Example 2

Explain why we can bend our arm, using the roles of bones and muscles.

Bones support and protect the body but cannot move on their own.

A muscle attached to the bone contracts (shortens) and pulls the bone, bending the arm.

▸ Because a muscle contracts and pulls the bone (bones support, muscles move)

Bones support and protect; muscles contract to move the body.

Unit-test style

Which statement about the human body is correct?

①The stomach absorbs the most nutrients

②The lungs take in oxygen and release carbon dioxide

③The heart is the organ that digests food

④Bones shorten on their own to move the body

⑤Arteries carry blood without oxygen

▸ ② The lungs take in oxygen and release carbon dioxide

The lungs are the respiratory organ that takes in oxygen on the inhale and releases carbon dioxide on the exhale.

Nutrients are absorbed by the small intestine (①), the heart circulates blood (③), muscles create movement (④), and arteries carry oxygen-rich blood (⑤).

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Mixture Separation