Lecture Notes on Human Metabolism and Nutritional States

Introduction

• Key terms in metabolism: Brunch Buffet
  • Assorted food items such as eggs, bacon, toast, biscuits, etc.
  • Importance of understanding nutrient processing in the body.

Nutrient Processing

• Carbohydrates and Fats: Directly oxidized for energy.
• Proteins: Amino acids must be converted for energy use.
• Storage:
  • Excess carbs and fats stored as larger molecules (like glycogen).
  • Excess amino acids stored as fat or glycogen after conversion.

Hormonal Regulation

• Insulin:
  • Helps manage nutrient storage and energy use.
  • Dysfunction can lead to metabolic disorders like diabetes.
• Metabolic Disorders:
  • Impaired nutrient storage and usage.
  • Importance of maintaining proper glucose levels.

Energy Conversion and Homeostasis

• Law of Conservation of Energy: Energy is neither created nor destroyed, only transformed.
• Metabolism:
  • Catabolizing reactions release energy.
  • Anabolizing reactions store energy.

Cellular Respiration

• Purpose: Conversion of glucose to ATP.
• Process:
  • Glucose reacts with oxygen to produce CO2, water, and ATP.
  • Involves glycolysis, pyruvic acid formation, the Kreb’s cycle.

Nutritional States

• Absorptive State:
  • Occurs during/after eating.
  • Extra glucose stored as glycogen or fat.
  • Basal Metabolic Rate (BMR) influences energy storage.
• Postabsorptive State:
  • Occurs when GI tract is empty.
  • Body utilizes stored nutrients.

Blood Glucose Regulation

• Normal blood glucose levels: 70-100 mg/dL
• High blood glucose: Risks include damage to blood vessels, increased risk of diseases.
  • Managed by insulin secretion.

Roles of Insulin and Glucagon

• Insulin:
  • Facilitates glucose storage (glycogenesis, lipogenesis).
  • Inhibits glycogen breakdown (glycogenolysis).
• Glucagon:
  • Released when glucose drops.
  • Triggers conversion of glycogen/fats to glucose (gluconeogenesis).

Lipids Transport

• Lipoproteins: Transport hydrophobic fats in blood.
  • LDL ("bad" cholesterol) and HDL ("good" cholesterol).

Diabetes and Metabolic Regulation

• Diabetes:
  • Insufficient insulin production or function.
  • Results in high blood sugar, weight loss due to energy from fat/protein.

Conclusion

• Understanding energy use and storage is crucial for health.
• Importance of maintaining balanced blood sugar levels.
• Encourage engagement with educational resources like Crash Course.

Acknowledgements

• Contributions from various professionals to the Crash Course series.