Chapter 23: Metabolism

Overview

• Metabolism refers to all chemical reactions in the body.
• It has two major components:
  • Anabolism (Anabolic Reactions)
  • Catabolism (Catabolic Reactions)

Anabolism

• Definition: Building larger molecules from smaller ones.
• Also known as synthesis reactions.
• Example: Forming glycogen from glucose molecules.
• Type: Endergonic (consumes energy).

Catabolism

• Definition: Breaking down larger molecules into smaller ones.
• Also known as decomposition reactions.
• Example: Breaking down glycogen into glucose.
• Type: Exergonic (releases energy).

Metabolic States

Absorptive State

• Occurs after eating, especially important in endurance sports.
• Carb Loading: Consuming large amounts of carbs to store energy for events like marathons.
• Process:
  • Carbs are broken down into glucose.
  • Excess glucose is not needed immediately and is stored as glycogen.
  • Insulin is the hormone driving storage.
• Reaction: Glycogenesis (creation of glycogen).

Post-Absorptive State

• Occurs when you haven't eaten for a while (e.g., during a race).
• Stored glycogen is broken down to release glucose for energy.
• Glucagon is the hormone that triggers this process when blood glucose levels are low.
• Reaction: Glycogenolysis (breakdown of glycogen).

Endurance Athletes

• Important to prepare by carb loading to ensure energy availability.
• During endurance events, rely on stored glycogen for a continuous glucose supply to muscles.

• Homework assignment of key concepts will be used as study material for exams.
• The lecture does not provide direct notes but guides on what to focus on for Chapter 23.
• Email the instructor for any questions regarding the homework or concepts discussed.