seegongsik
Grade 6 (age 11-12)

grade 6 Human Body Systems

Inside your body, digestion, circulation and breathing are working together at this very moment. Food that goes in through the mouth passes through the digestive organs one after another, is broken into tiny pieces, and its nutrients are absorbed in the small intestine. Blood pushed out by the heart carries those nutrients, and oxygen picked up in the lungs, all over the body; the lungs breathe in and out, taking in oxygen and getting rid of carbon dioxide. Press the digestive organ buttons in turn to follow the path of food, and switch between breathing in and out to compare how the lungs and diaphragm move.

The path of food: digestion

🍎 How digestion works
①Mouth: teeth break food into small pieces and mix it with saliva.
②Esophagus: muscles squeeze to push food down to the stomach.
③Stomach: mixes food with stomach juices and breaks it down further.
④Small intestine: breaks food down further and absorbs nutrients into the blood.
⑤Large intestine: absorbs water and pushes the remaining waste out through the anus.

Blood circulation

❤️ Blood circulation
①The heart keeps squeezing and relaxing, pushing blood like a pump.
②Arteries: vessels that carry blood from the heart to the body. The arteries going to the body carry oxygen-rich blood.
③Capillaries: very thin vessels that hand oxygen and nutrients to cells all over the body and pick up carbon dioxide.
④Veins: vessels that bring blood from the body back to the heart.
⑤When an adult is resting, the heart beats about 60 to 100 times a minute.

Breathing

🫁 Breathing
①Breathing in: the diaphragm moves down and the ribs move up, the chest gets bigger, the lungs swell and air comes in.
②Breathing out: the diaphragm moves up and the ribs move down, the lungs shrink and air goes out.
③Air travels nose → trachea → bronchi → lungs.
④In tiny air sacs in the lungs, oxygen passes into the blood and carbon dioxide comes out of it.
⑤During exercise the body uses more oxygen, so you breathe faster and your heart beats faster too.

Summary

Digestion
Mouth → esophagus → stomach → small intestine (absorbs nutrients) → large intestine (absorbs water)
Breaking food into small pieces and absorbing its nutrients.
Circulation
Heart → arteries → capillaries → veins → heart
Blood carries oxygen and nutrients all over the body and collects carbon dioxide.
Respiration
Breathing in (air with oxygen) ↔ breathing out (air with more carbon dioxide)
The lungs swap oxygen and carbon dioxide.
🎯 Key points
①Digestion: food passes mouth → esophagus → stomach → small intestine → large intestine, and nutrients are absorbed in the small intestine.
②Circulation: the heart pushes blood round the body through arteries → capillaries → veins.
③Breathing: the lungs take in oxygen and get rid of carbon dioxide.
④Working together, these systems get nutrients and oxygen to cells all over the body.
⑤That is also why you breathe hard and your heart races when you exercise.

Examples and Unit Test

Example 1
Which digestive organ absorbs most of the nutrients in food?
1
Food passes through the mouth → esophagus → stomach → small intestine → large intestine.
2
Nutrients are absorbed into the blood in the small intestine, while the large intestine mainly absorbs water.
▸ The small intestine
Press the small intestine button in the first picture and it says absorb nutrients.
Example 2
What do we call blood leaving the heart, going round the body and coming back, and which vessels carry oxygen-rich blood to the body?
1
The heart pumping blood round the whole body is called blood circulation.
2
The arteries going from the heart to the body carry oxygen-rich blood.
▸ Blood circulation / arteries
Arteries go from the heart to the body, veins go from the body back to the heart, and in between the capillaries hand over oxygen and nutrients.
Unit-test style
Which statement about how the body works is correct?
①The stomach absorbs more nutrients than any other organ.
②The small intestine absorbs nutrients from food.
③Carbon dioxide comes into the body when we breathe in.
④The heart is an organ that digests food.
⑤The large intestine breaks down nutrients to make energy.
▸ ② The small intestine absorbs nutrients from food.
1
The small intestine absorbs nutrients from food that has been broken down and sends them into the blood.
2
Most nutrients are absorbed in the small intestine (①), air with oxygen comes in when we breathe in (③), the heart pumps blood (④), and the large intestine absorbs water (⑤).
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