Grade 6 (age 11-12)

Human Body Systems

Your body digests, circulates, and breathes all at once. Food becomes nutrients in the digestive organs, blood from the heart carries them and oxygen through the body, and the lungs swap oxygen and carbon dioxide with each breath. Tap each digestive organ and toggle inhale and exhale to follow the flow.

Digestive Journey

🍎 Digestion Process

①Mouth: chew and dissolve with saliva

②Esophagus: peristalsis sends food to stomach

③Stomach: gastric juice dissolves food

④Sm. intestine: absorbs nutrients into blood

⑤Lg. intestine: absorbs water and excretes waste

Blood Circulation

❤️ Blood Circulation

①Heart pumps blood like a pump

②Artery: heart → body (oxygen-rich blood)

③Vein: body → heart (with CO₂)

④Capillary: delivers O₂ and nutrients to cells

⑤Blood circulates and delivers oxygen/nutrients

Respiratory System

🫁 Respiration

①Inhale: diaphragm down → lungs expand → O₂ in

②Exhale: diaphragm up → lungs contract → CO₂ out

③Alveoli exchange O₂↔CO₂

④Air path: nose → trachea → bronchi → alveoli

Summary

Digestion

Mouth → Esophagus → Stomach → Sm. intestine (nutrients) → Lg. intestine (water)

Breaking down food and absorbing nutrients

Circulation

Heart → Artery → Capillary → Vein → Heart

Blood delivers O₂ and nutrients throughout the body

Respiration

Inhale (O₂) ↔ Exhale (CO₂) = gas exchange

Lungs exchange oxygen and carbon dioxide

🎯 Key Points

①Digestion: food → nutrient absorption (mouth→esophagus→stomach→sm.intestine→lg.intestine)

②Circulation: heart pumps blood (artery→capillary→vein)

③Respiration: lungs exchange O₂↔CO₂

④All three systems cooperate to supply energy

⑤Exercise speeds up heart rate and breathing for this reason

Examples and Unit Test

Example 1

Which digestive organ mainly absorbs the nutrients in food?

Food moves in the order mouth → esophagus → stomach → small intestine → large intestine.

The small intestine absorbs nutrients into the blood, and the large intestine absorbs water.

▸ The small intestine

Digestion breaks food down to absorb nutrients. Nutrients are absorbed in the small intestine, water in the large intestine.

Example 2

What is it called when blood leaves the heart, travels around the body, and returns, and which vessel carries oxygen-rich blood?

The heart pumps blood around the whole body; this is called circulation.

Arteries, which carry blood from the heart to the body, carry oxygen-rich blood.

▸ Circulation / arteries

Arteries (heart→body, oxygen-rich), veins (body→heart), capillaries (deliver oxygen and nutrients).

Unit-test style

Which statement about the human body is correct?

①The stomach absorbs the most nutrients

②The small intestine absorbs the nutrients in food

③During an inhale, carbon dioxide enters the body

④The heart is the organ that digests food

⑤The large intestine breaks down nutrients to make energy

▸ ② The small intestine absorbs the nutrients in food

The small intestine absorbs nutrients from the broken-down food and sends them into the blood.

Nutrient absorption is done by the small intestine (①), an inhale brings in oxygen (③), the heart pumps blood (④), and the large intestine absorbs water (⑤).

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