BASIC SCIENCE E-NOTE
Topic:
Digestive System
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Meaning of Digestive System
The digestive system is a
group of organs in the body that work together to break down food into
simple substances that the body can use for energy, growth, and repair.
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Meaning of Digestion
Digestion is the process of breaking large pieces of food into
smaller, simple substances that can be absorbed into the blood.
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The Human Alimentary Canal
The alimentary canal is a
long tube through which food passes in the body.
Parts
of the Alimentary Canal:
- Mouth
– Chews food and mixes it with saliva.
- Oesophagus
– A tube that carries food to the stomach.
- Stomach
– Stores food and helps in digestion.
- Small Intestine
– Completes digestion and absorbs nutrients.
- Large Intestine
– Absorbs water from undigested food.
- Anus – Removes waste from the body.
Diagram of digestive system
🧪Digestion of Food by Enzymes
Enzymes are special substances that help break down food.
Digestion
of Carbohydrates
- Starts in the mouth
- Enzyme: Salivary amylase
- Example foods: rice, yam, bread
Digestion
of Proteins
- Occurs in the stomach
- Enzyme: Pepsin
- Example foods: meat, beans, fish
Digestion
of Fats and Oils
- Occurs mainly in the small intestine
- Enzyme: Lipase
- Example foods: palm oil, butter, groundnut oil
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Absorption of Digested Food
- Absorption takes place in the small intestine.
- The small intestine has finger-like structures called villi.
- The villi help digested food to enter the bloodstream.
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Storage of Digested Food
- Excess glucose is stored in the liver as glycogen.
- Some nutrients are also stored in the muscles
and fat tissues.
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Importance of Digestion
Digestion is important because it:
- Provides energy
- Helps growth and body repair
- Keeps the body healthy
- Supports daily activities
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