Human Nutrition Fundamentals

Human Nutrition

• Nutrition: The process organisms use to obtain and utilize food for growth, repair, and energy production.
• Autotrophic Nutrition: Plants create their own food using photosynthesis.
• Heterotrophic Nutrition: Animals, including humans, depend on other organisms for food.
• Balanced Diet: Provides necessary nutrients for optimal health, consisting of:
  • Carbohydrates: Primary energy source (rice, bread, pasta).
  • Proteins: Essential for growth and repair (meat, fish, beans).
  • Fats: Energy storage and insulation (butter, oils).
  • Vitamins: Crucial for various bodily functions.
    • Vitamin A: Supports vision and skin health.
    • Vitamin C: Promotes immunity and wound healing.
    • Vitamin D: Essential for bone health.
  • Minerals: Strengthen bones, teeth, and support body processes.
    • Calcium: Strengthens bones.
    • Iron: Critical for hemoglobin production.
  • Water: Vital for all biochemical reactions.
  • Fiber: Aids digestion and prevents constipation.

The Digestive System

• Mouth: Mechanical and chemical digestion. Mechanical breakdown by teeth; chemical digestion through salivary amylase.
  • Saliva: Contains amylase, an enzyme that breaks down starch into maltose.
• Esophagus: Transports food to the stomach via peristalsis (muscle contractions).
• Stomach: Churns food; produces gastric juice with HCl (kills bacteria) and pepsin (protein breakdown).
• Small Intestine:
  • Duodenum: Further digestion with enzymes from the pancreas and bile from the liver.
  • Ileum: Nutrient absorption into the blood through villi.
• Large Intestine: Primarily absorbs water and forms feces.
• Rectum and Anus: Store and expel waste.

Role of Enzymes in Digestion

• Enzymes: Biological catalysts that speed up digestion.
  • Amylase: Breaks down starch into maltose.
  • Protease: Breaks down proteins into amino acids.
  • Lipase: Breaks down fats into glycerol and fatty acids.

Bile

• Bile: Produced by the liver, stored in the gallbladder.
• Functions:
  • Neutralizes stomach acid.
  • Emulsifies fats, increasing surface area for lipase action.

Transport in Plants

• Importance of Transport: Distribution of water, minerals, and nutrients throughout a plant.
• Xylem: Transports water and minerals from roots to leaves.
  • Structure: Hollow tubes reinforced with lignin.
  • Process:
    • Root hair cells absorb water through osmosis.
    • Transpiration (water loss from leaves) creates a pulling force.
• Phloem: Transports sugars and amino acids from leaves to other plant parts.
  • Structure: Sieve tubes with companion cells.
  • Process: Translocation (bidirectional movement of substances).

Transpiration

• Transpiration: Loss of water vapor from aerial plant parts.
• Factors Affecting Transpiration:
  • Light intensity: Increases transpiration in stronger light.
  • Temperature: Higher temps increase evaporation.
  • Humidity: Higher humidity decreases transpiration.
  • Wind: Increases transpiration by removing water vapor near the leaf surface.

Adaptations of Plants

• Xerophytes: Plants adapted to dry conditions.
  • Examples: Thick cuticles, reduced leaf size, and special structures to conserve water.
• Hydrophytes: Plants adapted to water environments.
  • Examples: Extensive air spaces for buoyancy.

Transport in Animals

• Circulatory System: Transports nutrients, oxygen, and waste throughout the body.
  • Types:
    • Open circulatory systems (e.g., insects)
    • Closed circulatory systems (e.g., humans).

Components of the Circulatory System

• Heart: Pumps blood throughout the body.
  • Structure: Four chambers: Right atrium, right ventricle, left atrium, left ventricle.
  • Pathway of Blood Flow:
    • Deoxygenated blood enters the right atrium through vena cava.
    • Pumped to the right ventricle and then to lungs via pulmonary artery.
    • Oxygenated blood returns to the left atrium via pulmonary vein.
    • Pumped to the left ventricle and body via aorta.
• Blood Vessels: Arteries carry blood away from the heart (except for pulmonary artery); veins carry blood toward the heart (except for pulmonary vein); capillaries facilitate gas/nutrient exchange.
• Blood: Consists of:
  • Red blood cells: Transport oxygen via hemoglobin.
  • White blood cells: Fight infections.
  • Platelets: Facilitate blood clotting.
  • Plasma: Transports nutrients, hormones, waste.

The Heart

• Heart Chambers: Right and left atria, right and left ventricles.
• Heart Valves: Prevent backflow of blood (tricuspid, bicuspid, semilunar valves).
• Cardiac Cycle:
  • Atrial Systole: Atria contract, pushing blood into ventricles.
  • Ventricular Systole: Ventricles contract, pumping blood to lungs and body.
  • Diastole: Heart relaxes, chambers fill with blood.

Double Circulation

• Pulmonary Circulation: Blood flow between the heart and lungs.
• Systemic Circulation: Blood flow between the heart and the rest of the body.