Nutrition Overview: Macronutrients & Micronutrients

Macronutrients

• Carbohydrates:
  • Sources: Bread, rice, pasta
  • Function: Quick energy
  • Example: Glucose → ATP
• Proteins:
  • Sources: Meat, beans, eggs
  • Function: Growth, repair, enzymes
  • Example: Amino acids → Muscle building
• Fats:
  • Sources: Butter, nuts, oils
  • Function: Long-term energy, insulation
  • Example: Fatty acids & Glycerol

Micronutrients

• Vitamins:
  • Vitamin C: Boosts immunity (Sources: Citrus fruits)
  • Vitamin D: Bone health (Sources: Sunlight, fish)
• Minerals:
  • Iron: Red blood cells (Sources: Spinach)
  • Calcium: Bone strength (Sources: Milk, kale)

Macronutrients vs Micronutrients

• Macronutrients: Required in large amounts. Examples: protein, fat, carbohydrates, and water.
• Micronutrients: Required in small amounts. Examples: Vitamins and certain minerals.

Diet Comparisons

• Vegan: Made up of only plant-based foods. Pros: Environmentally friendly, ethical. Cons: Risk of B12 deficiency, limited protein sources, may lack protein variety
• Vegetarian: Diet that does not contain meat. Pros: Balance of ethics and nutrition. Cons: May lack protein variety
• Non-Vegetarian: Diet that contains both meat and plant-based foods. Pros: Complete protein, rich in iron. Cons: High cholesterol risk, not sustainable

Key Digestive Enzymes

• Amylase: Starch → Maltose (Saliva & Pancreas)
• Pepsin: Proteins → Peptides (Stomach)
• Lipase: Fats → Fatty acids & Glycerol (Pancreas)

Digestive System: Mouth

• Teeth: Physical digestion (chewing)
• Saliva: Chemical digestion, contains amylase which breaks down starch into maltose.

Digestive System: Tongue

• Helps mix food with saliva
• Rolls food into a bolus for easier swallowing

Digestive System: Oesophagus

• Function: Muscular tube that connects the mouth to the stomach. Moves food through peristalsis, wave-like muscular contractions

Digestive System: Stomach

• Temporarily stores food and mixes with gastric juices.
• Physical digestion: Churns food
• Chemical digestion:
  • Hydrochloric acid (HCl): Kills bacteria, provides acidic environment for enzymes (e.g., pepsin).
  • Pepsin: Breaks down proteins.
  • Mucus: Protects stomach walls from acid.

Digestive System: Liver

• Produces bile that emulsifies fats (breaks them into smaller droplets) for easier digestion.
• Stores and releases nutrients(glucose, vitamins, minerals).
• Detoxifies harmful substances in the blood.

Digestive System: Gallbladder

• Stores and concentrates bile produced by the liver.
• Releases bile into the small intestine when fats are present.

Digestive System: Pancreas

• Produces digestive enzymes:
  • Amylase: Breaks down starch into maltose
  • Lipase: Breaks down fats into fatty acids and glycerol
  • Trypsin: Breaks down proteins into smaller peptides
• Produces sodium bicarbonate to neutralize stomach acid in the small intestine

Digestive System: Small Intestine

• Divided into three parts: duodenum, jejunum, ileum
• Receives bile and pancreatic juices for chemical digestion.
• Nutrients absorbed into the bloodstream (sugars, amino acids, fatty acids).
• Villi and microvilli increase surface area for maximum absorption

Digestive System: Large Intestine (Colon)

• Absorbs water and salts from undigested food.
• Forms and stores solid waste (feces).
• Houses bacteria that produce Vitamin K and break down undigested carbohydrates (fiber).

Digestive System: Rectum

• Stores feces until defecation

Digestive System: Anus

• Opening through which waste exits the body, controlled by internal and external sphincter muscles.