Biology Chapter 9: Metabolism

Chapter 9: Metabolism

• Metabolism is the totality of chemical reactions in the body, crucial for maintaining life.
• Anabolic reactions build complex molecules, such as glucose to glycogen.
• Catabolic reactions break down complex molecules, like glycogen to glucose to create carbon dioxide, water, and ATP.
• ATP is the primary energy currency, storing and releasing energy as needed.
• All macronutrients must become Acetyl-CoA before entering cellular respiration.
• Aerobic respiration utilizes oxygen.
• Anaerobic respiration doesn't require oxygen.
• Cellular respiration releases energy, CO2, and water by oxidizing food molecules.
  • LEO (Lose Electron Oxidation) and GER (Gain Electron Reduction) denote electron transfer.
• Carbohydrate metabolism includes glycolysis (2 ATP), the transition reaction, the citric acid cycle (2 ATP), and the electron transport chain (30-32 ATP).
  • Anaerobic respiration converts pyruvate to lactate, important during intense exercise.
• Fat metabolism (lipolysis) involves fatty acid breakdown (β-oxidation) to Acetyl-CoA.
  • Fat provides more energy (9 kcal/g) than carbohydrates (4 kcal/g).
  • Efficient fat metabolism needs oxaloacetate from glucose.
• Ketosis occurs when carbohydrate intake is low. Low oxaloacetate causes Acetyl-CoA to form ketones. Ketosis occurs in type 1 diabetes due to no insulin.
• Protein metabolism happens mainly in the liver, creating glucose from glucogenic amino acids. Nitrogen is removed and eliminated as urea in urine.
• Alcohol metabolism converts alcohol to Acetyl-CoA through the alcohol dehydrogenase pathway, primarily used for fat synthesis. Women have slower alcohol metabolism.
• Fasting involves breaking down glycogen and fat, generating ketones.
• Feasting involves synthesizing glycogen and protein, forming urea.

Chapter 10: Energy Balance

• Bomb calorimeter measures the energy content of food.
• Basal Metabolic Rate (BMR) represents the minimal energy for vital functions (60-70% of total expenditure).
• Physical activity increases BMR by 25-40%.
• The thermic effect of food accounts for 5-10% of energy consumption.
• Body fat assessment methods include underwater weighing, skinfold thickness, and bioelectrical impedance.
• Genetics plays a significant role (40-70%) in body weight.
• Set-point theory suggests a genetically predetermined weight and fat content.
• Weight management considers that 1 lb of fat equates to 3,500 kcal.
• Gastroplasty involves surgical procedures like gastric banding, bypass, and sleeve gastrectomy for weight loss.
• Eating disorders:
  • Anorexia nervosa is characterized by self-starvation, distorted body image, and has consequences such as low bone mass, muscle wasting, anemia, and lanugo.
  • Bulimia nervosa involves binge eating and purging. Consequences include electrolyte imbalances, dental decay, and ulcers.
  • Nutrition therapy focuses on regular eating patterns, food records, behavior modification, and avoidance of trigger foods.
  • Leptin is a hormone signaling satiety.

Chapter 11: Fitness and Energy

• Fitness program characteristics depend on mode (type of exercise), duration, frequency, intensity, and Rate of Perceived Exertion (RPE) scale.
• Immediate energy source for muscle use is ATP.
• Phosphocreatine provides high-energy for about 10 seconds.
• Carbohydrates are the primary energy source for short to medium-term, high-intensity exercise. Carbohydrate breakdown can occur aerobically (28-30 ATP) or anaerobically (pyruvate to lactate; 2 ATP). Muscle glycogen is used for up to two hours of activity.
• Fat is the primary energy source for long, low-intensity exercise. Fat provides 9 kcal/g but is slower to metabolize than carbohydrates.
• Protein is a minor fuel source; essential branched-chain amino acids can be converted to glucose via gluconeogenesis.