EHS_385_BioenergeticsI_S25_cfs

Page 1: Introduction to Bioenergetics

• Focus on energy as it relates to physical activity.

• Free energy equation:

  • C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy

• Importance of combustion and oxidation in energy release.

Page 2: Fuels Available for Physical Activity

• Three macronutrients:

  • Carbohydrate

  • Fat

  • Protein

• High-energy phosphates serve as a ready supply for energy.

• Bioenergetics: Process of extracting energy from macronutrients and converting it to ATP (Adenosine Triphosphate), the universal energy source for cells.

Page 3: Structure and Formation of ATP

• Structure of ATP illustrated in Fig 3.10.

• ATP formation pathways:

  • Phosphocreatine (PC) breakdown

  • Degradation of glucose and glycogen

• Glycolysis pathways include anaerobic (without oxygen) and aerobic (with oxygen) processes.

Page 4: Carbohydrates - Fuels for Exercise

• Macronutrient types:

  • Monosaccharides: Simple sugars (e.g., glucose, fructose)

  • Disaccharides: Two combined monosaccharides (e.g., sugar)

  • Polysaccharides: Complex carbohydrates made up of three or more monosaccharides.

Page 5: Glucose and Glycogen

• Glucose: Blood sugar crucial for energy.

• Glycogen: Polysaccharide storage form of glucose.

  • Stored primarily in the liver and skeletal muscles.

  • Process of glycogen synthesis involves the enzyme glycogen synthase.

  • Glycogenolysis: Breakdown of glycogen into glucose.

• Normal blood glucose levels are between 70-200 mg/dL.

Page 6: Glycogen Storage Locations

• Glycogen is stored primarily in:

  • Skeletal muscle (80-85%)

  • Liver (15-20%)

• Glycogenolysis allows conversion of glycogen to glucose for energy, occurring in both liver and muscles, with gluconeogenesis occurring only in the liver.

Page 7: Fats as Fuels for Exercise

• Types of fats:

  • Fatty acids: Main type of fat used by skeletal muscle.

  • Triglycerides: Storage form of fat, broken down into glycerol and fatty acids via lipolysis.

  • Phospholipids: Not an energy source.

  • Steroids: Derived from cholesterol and also not an energy source.

• Glycerol can be used to produce energy or synthesize glucose.

Page 8: Characteristics of Fats

• Technical name for Fat: Triacylglycerol (triglyceride)

• Composition: Generally consists of a glycerol backbone and three fatty acid chains.

• Stored primarily in adipocytes (fat cells) and intramuscular triglycerides (IMTG), but must be mobilized for energy use.

Page 9: Protein Fuels for Exercise

• Proteins are composed of amino acids (AA).

• AA can be:

  • Converted to glucose in the liver (gluconeogenesis)

  • Converted to metabolic intermediates for energy.

• Overall, protein is not a primary energy source during exercise.

Page 10: Protein Structure and Function

• Proteins include an 'Amine' group, which contains nitrogen.

• Essential amino acids must be obtained through food.

• Proteins are crucial for building and repairing body tissues, including muscle growth, which requires a positive nitrogen balance.

Page 11: ATP Production Methods

• Muscles store limited ATP; need constant production for movement.

• Three metabolic pathways for ATP production:

  • Anaerobic pathways (without oxygen):

    • Phosphocreatine breakdown

    • Glycolysis

  • Aerobic pathway (with oxygen):

    • Oxidative pathway.

Page 12: Phosphate Energy Systems

• Phosphocreatine (PC) breakdown allows for rapid ATP production.

  • ATP-PC System: Simplest way to create ATP, reliant on creatine phosphate.

• ATP as the energy currency of cellular work, with energy released by breaking down ATP to ADP.

Page 13: The Phosphagen System

• Activated during short bursts of high-intensity activities such as resistance training or sprinting.

• Involves the combination of creatine phosphate (CP) and ADP for quick ATP resynthesis.

• Limitations include storage capacity of PC and recovery time needed post-exercise.

Page 14: High-Energy Phosphates

• Phosphocreatine is stored in muscle cytoplasm, providing a limited but readily available energy supply.

• Distinction between phosphocreatine (cellular source) and creatine supplements.

Page 15: Immediate Energy Supply and Creatine

• High-energy phosphates provide energy within seconds through anaerobic ATP creation.

• Investigating benefits of creatine supplementation for high-intensity, short-duration activities with recovery times.

Page 16: Summary of Energy Sources

• ATP and Phosphocreatine: Limited storage but rapid availability for production.

• Carbohydrate: Stored as glycogen in muscle and liver; circulating as glucose.

• Fat: Stored as triacylglycerols in adipose tissue.

• Protein: No storage capacity; used functionally in the body.

• Future topics include glycolysis, TCA/Kreb’s Cycle, and the Electron Transport Chain.