Digestive system
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先生の方へ: Digestive system(KS3 Science、Biology)向けのすぐ使えるレッスンスライド, 復習ノート, 図解 — レッスンで使うか、生徒がライブゲームとして遊ぶインタラクティブなクラス活動としてトピックを実施できます。
レッスンノート
Overview of the Digestive System
- The digestive system breaks down food into small molecules that can be absorbed into the blood.
- It consists of many organs, each with a specific role in digestion.
- Enzymes are biological catalysts that speed up chemical reactions in digestion.
- Some bacteria live in the large intestine; they protect against harmful bacteria and help digest food.
Organs Food Travels Through
- Mouth: teeth mechanically break food; saliva contains amylase which breaks down starch.
- Oesophagus: walls squeeze to move food to the stomach.
- Stomach: muscular walls mechanically break food; contains hydrochloric acid to kill bacteria; protease breaks down proteins.
- Small intestine: contains villi with a large surface area for absorbing digested food into the blood.
- Large intestine: absorbs water from undigested food.
- Rectum: stores faeces (waste material) before it leaves through the anus.
Accessory Organs (Food Does Not Pass Through)
- Liver: produces bile to neutralise stomach acid.
- Gall bladder: stores bile and releases it into the small intestine.
- Pancreas: produces enzymes protease, amylase, and lipase (which breaks down lipids) and releases them into the small intestine.
Enzymes in Digestion
- Amylase (in saliva and from pancreas) breaks down starch (carbohydrates).
- Protease (in stomach and from pancreas) breaks down proteins.
- Lipase (from pancreas) breaks down lipids (fats).
- Enzymes work best at specific pH conditions; protease works best in acidic conditions in the stomach.
Absorption and Waste
- Digested food is absorbed in the small intestine via villi, which increase surface area for faster absorption.
- Water is absorbed in the large intestine.
- Undigested material forms faeces, stored in the rectum until eliminated.
Diagram
スライド
練習問題
無料プレビュー — 54問中8問。すべて見るには登録を。
1.Which organ contains hydrochloric acid that kills bacteria?
Easy- AStomach
- BSmall intestine
- CLarge intestine
- DLiver
2.Where are villi found and what is their main function?
Easy- ASmall intestine; to absorb digested food
- BLarge intestine; to absorb water
- CStomach; to kill bacteria
- DOesophagus; to move food
3.In which organ is water absorbed?
Easy- ALarge intestine
- BSmall intestine
- CStomach
- DRectum
4.Which organ stores faeces before it leaves the body?
Easy- ARectum
- BAnus
- CLarge intestine
- DColon
5.Which enzyme breaks down starch, and where is it produced?
Easy- AAmylase; mouth
- BProtease; stomach
- CLipase; pancreas
- DAmylase; pancreas
6.What is the role of bile in digestion?
Easy- ANeutralise stomach acid
- BBreak down proteins
- CBreak down carbohydrates
- DAbsorb water
7.Enzymes are biological catalysts. What does this mean?
Easy- AThey speed up chemical reactions without being used up
- BThey are used up in reactions
- CThey slow down reactions
- DThey are only found in the stomach
8.Which organ produces enzymes that are passed into the small intestine, including protease, amylase, and lipase?
Easy- APancreas
- BLiver
- CGall bladder
- DStomach
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