Anatomy 1352 - Unit 8: Nutrition and Metabolism

Overview

• Unit 8 focuses on nutrition and metabolism, a short chapter that is separate from the digestive system content of Unit 7.
• The primary focus is on obtaining chemical energy from nutrients for growth, repair, and normal body functioning.
• The chapter will be followed by a brief introduction to the urinary system.

Key Concepts

Food Pyramid and Metabolism

• The lecture dismisses the food pyramid as "pointless" but acknowledges the need for various nutrients.
• Metabolism is the sum of all chemical reactions in the body and consists of:
  • Catabolism: Breaking down large molecules into smaller ones, releasing energy (exergonic reactions).
  • Anabolism: Building up complex molecules from smaller ones, requiring an energy input (endergonic reactions).
• Both processes occur simultaneously in the body.

Nutrients

• Nutrients provide essential chemicals, energy sources (lipids & carbohydrates), growth factors (vitamins), and repair components (amino acids).
• ATP is the main energy currency, consisting of adenosine (adenine + ribose) and three phosphates.
• Breaking ATP releases energy, which is used in various bodily reactions.

Cellular Respiration

• Glucose is the primary energy source, broken down through cellular respiration into ATP, CO2, and water.
• Cellular respiration occurs in four steps:
  1. Glycolysis: Breakdown of glucose into pyruvate, producing ATP and NADH.
  2. Formation of Acetyl CoA: Conversion of pyruvate to acetyl CoA (dependent on oxygen availability).
  3. Krebs Cycle: Complete breakdown of acetyl CoA into CO2, with extensive NADH production.
  4. Electron Transport Chain (ETC): Occurs in mitochondria, where most ATP is generated; electrons are ultimately accepted by oxygen to form water.

Glucose and Glycogen

• Glycogenesis: Formation of glycogen from glucose for storage (muscle cells and liver).
• Glycogenolysis: Breakdown of glycogen into glucose, prompted by the hormone glucagon.
• Gluconeogenesis: Creation of glucose from non-carbohydrate sources (amino acids, lactic acid, triglycerides), primarily in the liver.

Lipids and Triglycerides

• Triglycerides: Main form of stored energy, broken down when glucose is low (lipolysis).
• Lipogenesis: Formation of lipids from excess acetyl CoA.
• Ketogenesis: Conversion of excess glycerol into ketone bodies during high rates of lipolysis.

Proteins and Amino Acids

• Proteins are not primarily used for energy but can be converted into glucose or triglycerides.
• Deamination: Process in the liver to remove ammonia from amino acids, converting it to urea for excretion.
• Essential amino acids: Cannot be synthesized by the body and must be obtained from the diet.

Conclusion

• Unit 8 covers complex metabolic processes essential for energy production and nutrient utilization.
• Next step involves understanding how the body processes and stores nutrients, with a focus on specific pathways and enzymes involved.

Note: This summary includes integrated concepts from metabolic pathways, emphasizing the flow of energy and the roles of glucose, lipids, and proteins. Further details can be found in the course materials.