Bioenergetics pt 1

Metabolism

• Definition: All chemical reactions in the body leading to:

  • Catabolism: Breakdown of cell components/molecules

  • Anabolism: Build up of cell components/molecules

Sources of Energy

• Macronutrients and their building blocks:

  • Glucose (from carbohydrates)

  • Free Fatty Acid (from fats)

  • Amino Acids (from proteins)

• Primary nutrients used for energy: fats and glucose.

• Amino Acids contribute a smaller amount of energy.

Glucose Metabolism

1. Intake: Often in the form of Starch (polysaccharides)

2. Storage: Glycogen in liver and muscles

3. Distribution:

   • Monosaccharides (glucose, fructose, galactose) are utilized and found in the blood.

   • Glycogenolysis: Process where glycogen is converted back to glucose for energy.

   • Glycogen is critical for maintaining blood sugar and supporting normal bodily functions.

Free Fatty Acid (Fat)

• Definition: Primary lipid used by muscle for energy.

• Triglyceride: Storage form of fatty acids, made up of a glycerol molecule and up to three fatty acids.

• Lipolysis: Process of breaking down triglycerides into glycerol and fatty acids for energy usage.

Amino Acids

• Types: More than 20, categorized as essential (must be ingested) and non-essential.

• Function: Provides structure for cells and some amino acids can be converted into glucose via gluconeogenesis.

Bioenergetics

• Definition: Study of energy transfer in living organisms.

• Key elements of bioenergetics include:

  1. Coupled reactions: Reactions that release energy, powering another reaction.

  2. Enzymes: Biological catalysts that speed up chemical reactions.

  3. Oxidation-reduction reactions: Oxidation (loss of electrons) and reduction (gain of electrons) occur simultaneously.

  4. Substrates and products: Substrates are acted upon by enzymes; products are formed from these substrates.

  5. Shuttles and transporters: Required for some molecules to diffuse across membranes.

Thermodynamics and ATP

• 1st Law of Thermodynamics: Energy cannot be created or destroyed, only transferred.

• ATP (Adenosine Triphosphate): The body's energy currency, used immediately for biological work or stored for later.

Formation and Function of ATP

• Components of ATP:

  • Adenine (nucleobase)

  • Ribose (a sugar)

  • Three phosphate molecules

• ATP is essential for muscle contraction and is rapidly regenerated during energy consumption.

Energy Release from ATP

• ATP serves as an immediate energy source for cellular activities.

• ATPase: Enzyme that catalyzes the breakdown of ATP to release energy.

Oxidation-Reaction Dynamics

• Oxidation: Loss of an electron (OIL - Oxidation Is Losing)

• Reduction: Gain of an electron (RIG - Reduction Is Gaining)

Importance of ATP

• While ATP is not the only energy molecule, it is the most critical.

• Cells continuously use and regenerate ATP efficiently (10 million per second).

Overview of Bioenergetics

• Bioenergetics involves a series of reactions transferring energy from food to biological energy equivalents. Approximately 25% of energy is utilized in vital processes.

Energy Pathways

• Anaerobic ATP Synthesis: Does not require oxygen, utilizes phosphocreatine breakdown and glycolysis.

• Aerobic ATP Synthesis: Requires oxygen, occurs via oxidative phosphorylation.

Energy Pathways: Aerobic vs Anaerobic

• Anaerobic:

  • Generates ATP rapidly but in limited quantities.

  • Respiration occurs in the sarcoplasm, utilizing only carbohydrates.

• Aerobic:

  • Capable of generating substantial volumes of ATP.

  • Respiration occurs within mitochondria and utilizes all three macronutrients.

Total Daily Energy Expenditure (TDEE)

• TDEE Formula: TDEE = BMR + TEF + PA

  • BMR (Basal Metabolic Rate): Energy expended at rest, crucial for basic body functions, influenced by sex, age, ethnicity, body composition, genetics, height, and weight.

  • TEF (Thermic Effect of Food): Calories burned to digest, metabolize, and utilize food; varies by nutrient type.

  • PA (Physical Activity): Additional calories expended above resting levels, measured in kilocalories.

  • NEAT (Non-Exercise Activity Thermogenesis): Activity that helps maintain healthy body weight over a lifetime.