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Grade 6 (age 11-12)

grade 6 Human Body Systems

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 the digestive organs and switch inhale and exhale. Heart rate 72 is an adult-at-rest example, and there is no exercise slider.

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
②Arteries leave the heart. Body arteries are oxygen-rich, but the pulmonary artery carries more CO₂
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
⑤Exercise speeds heart rate and breathing for this reason

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?
1
Food moves in the order mouth → esophagus → stomach → small intestine → large intestine.
2
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?
1
The heart pumps blood around the whole body; this is called circulation.
2
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
1
The small intestine absorbs nutrients from the broken-down food and sends them into the blood.
2
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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