Digestion (Junior Cert Home Economics): Revision Notes

Digestion

What is Digestion?

• Definition: The process by which the body breaks down food.
• Macronutrients: Proteins, fats, and carbohydrates must be digested before use.
• Micronutrients: Vitamins, minerals, and water do not require digestion and can be used by the body as they are.

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Steps in Digestion

1. Physical Breakdown:

• Food is chewed by teeth and churned in the stomach.
• Breaks food into smaller pieces.

2. Chemical Breakdown:

• Digestive enzymes break down proteins, fats, and carbohydrates.
• Each enzyme works on a specific nutrient:
• Proteins → Amino acids
• Fats → Fatty acids and glycerol
• Carbohydrates → Simple sugars (e.g., glucose)

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Digestive Enzymes

• Special substances that chemically break down food.
• Each enzyme only works on one nutrient (e.g., fat enzymes won't affect carbohydrates).

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Functions of the Digestive System

1. Break Down macronutrients (digestion).
2. Absorb nutrients into the bloodstream.
3. Excrete waste from the body.