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
Intake: Often in the form of Starch (polysaccharides)
Storage: Glycogen in liver and muscles
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:
Coupled reactions: Reactions that release energy, powering another reaction.
Enzymes: Biological catalysts that speed up chemical reactions.
Oxidation-reduction reactions: Oxidation (loss of electrons) and reduction (gain of electrons) occur simultaneously.
Substrates and products: Substrates are acted upon by enzymes; products are formed from these substrates.
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.