Metabolism, Nutrition, and Body Temperature

Overview

• Metabolism

  • The sum of all chemical processes that occur in the body in order to maintain life.

  • Split into two main categories:

  • Catabolism: Breaking down complex compounds into simpler ones.

    • Example: Cellular respiration where nutrients are catabolized to generate ATP.

  • Anabolism: Building simple compounds into needed substances.

    • Example: Synthesis of proteins from amino acids.

Nutritional Guidelines

• Recommended Daily Caloric Distribution:

  • Carbohydrates: 55% to 60%

  • Fats: 30% or less

  • Proteins: 15% to 20%

• Dietary Recommendations:

  • Minimize simple sugars; emphasize complex carbohydrates (e.g., starches and fibers).

  • Monitor the glycemic index of foods to understand their impact on blood glucose levels.

Types of Metabolic Activities

• Anaerobic Metabolism:

  • Occurs in the cytoplasm without oxygen.

  • Produces 2 ATP, lactic acid as a byproduct; seen during sprinting when quick energy is needed.

• Aerobic Metabolism:

  • Occurs in the mitochondria with oxygen.

  • Produces 36-38 ATP, carbon dioxide (CO2), and water; utilized during moderate exercise such as walking or jogging.

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Nutrient Metabolism

• Carbohydrates:

  • Main energy source; stored as glycogen in liver and muscle.

  • Excess glucose is converted to fat.

• Fats:

  • Used for energy. Not used by the brain directly; stores excess calories.

  • Ketones (metabolized fatty acids) may serve as an energy source for the brain.

• Proteins:

  • No storage form; amino acids are utilized based on body need.

Metabolic Rate

• Defined as the rate at which cellular respiration converts nutrients to ATP.

• Generally decreases with age.

• Measured in kilocalories.

Vitamins and Minerals

• Vitamins:

  • Water-soluble vitamins (B and C) are not stored and need regular replenishment through diet.

  • Fat-soluble vitamins (A, D, E, and K) are stored in the liver and fatty tissues.

• Minerals:

  • Essential for body structure, fluid balance, muscle contraction, nerve impulse conduction, and blood clotting.

Body Temperature Regulation

• Mechanisms of Heat Loss:

  • Radiation, Convection, Evaporation, Conduction.

• Temperature Regulation:

  • Controlled by the hypothalamus; integrates signals for maintaining homeostasis.

  • Responses include vasoconstriction and shivering in cold, vasodilation and sweating in heat.

Nutritional Disorders

• Malnutrition:

  • Deficiency or excess of nutrients leading to health issues.

  • Protein-energy malnutrition encompasses conditions like marasmus and kwashiorkor.

• Food Allergies:

  • Reactions to allergens (food or additives); can be mild to severe.

Weight Control

• Body Mass Index (BMI):

  • Tool to estimate body fat;

  • Obese: BMI > 30, Overweight: 25-30, Normal: 18-25, Underweight: < 18.5.

• Strategies for Weight Control:

  • Combination of diet and exercise; consider high-intensity interval training for effectiveness.