Food and Digestion Notes
Balanced Diet
- A balanced diet is essential for obtaining all necessary food substances.
- Nutrients like carbohydrates, proteins, fats (lipids), vitamins, and minerals provide raw materials for the body.
Key Nutrients and Their Importance
- Carbohydrates (starch, sugars): Energy (respiration); sources: pasta, bread, rice, potatoes.
- Proteins: Growth and repair; sources: meat, fish, beans.
- Vitamins (e.g., vitamin C): Health; sources: fruits and vegetables (e.g., oranges).
- Minerals (e.g., calcium): Health; sources: fruits, vegetables, dairy (e.g., milk).
- Fiber: Prevents constipation; sources: wholemeal bread, wholegrain rice, fibrous vegetables.
- Water: Dissolves substances, fills cells; essential for health.
- Starch turns iodine solution blue-black.
- Nutrition labels provide information on food content and energy (kilojoules, kJ).
- Energy needs vary based on activity level, age, and gender.
Health Considerations
- Excess fat leads to heart disease and obesity.
- Insufficient food intake causes starvation and weakness.
- Malnutrition includes obesity, starvation, and deficiency diseases (e.g., scurvy from vitamin C deficiency).
Digestion
- Digestion breaks down large, insoluble substances into small, soluble ones.
- Enzymes speed up digestion.
The Gut
- Digestion occurs in the gut.
- The small intestine is folded and covered with villi and microvilli to increase surface area for absorption.
- The small intestine wall is one-cell thick for easy diffusion of molecules into the blood.
- Digested food molecules are transported in blood plasma.