Chapter 3: Bioenergetics of Exercise and Training Flashcards
Bioenergetics
- The flow of energy in a biological system
- Primarily concerned with converting macros into usable forms of energy (ATP)
Energy
The capacity to do work
Catabolism
- The breakdown of large molecules into smaller molecules
- Associated with the release of energy
Anabolism
- The synthesis of larger molecules from smaller molecules
- Can be accomplished using the energy released from catabolism
Exergonic Reactions
Energy-releasing reactions that are generally catabolic
Endergonic Reactions
Require energy and include anabolic processes
Metabolism
The total of all catabolic/exergonic and anabolic/endergonic reactions in a biological system
Adenosine Triphosphate (ATP)
- Composed of adenosine and three phosphates
- Potential energy in bond drives all biological work
Hydrolysis
- The breakdown of one molecules of ATP to yield energy
- Requires one molecule of water
ATPase
Enzyme that catalyzes the hydrolysis of ATP
Myosin ATPase
The enzyme that catalyses ATP hydrolysis for crossbridge cycling
Calcium ATPase
Hydrolyzes ATP when pumping calcium into the sarcoplasmic reticulum
Sodium-Potassium ATPase
Hydrolyzes ATP to maintain the sarcolemmal concentration gradient after depolarization
ATP Hydrolysis
ATP + H2O –> ADP + Pi + H+ + Energy
ADP
- Adenosine diphosphate
- Result of ATP hydrolysis
Pi
Inorganic Phosphate
AMP
- Adenosine Monophosphate
- Result of ADP hydrolysis
3 Basic Energy Systems
- Phosphagen System
- Glycolysis
- Oxidative System
Anaerobic Processes
- Does not require the presence of oxygen
- Phosphagen system
- Glycolytic systems
- Occur in the sarcoplasm of the muscle cell
Aerobic Processes
- Requires the presence of oxygen
- Krebs cycle
- Oxidative system
- Occur in the mitochondria of the muscle cell
Which macronutrient can be metabolized anaerobically?
Carbs
Phosphagen System
- Drives short-term, high-intensity activities
- Highly active at the start of activity, regardless of intensity
- Relies on hydrolysis of ATP and breakdown of creatine phosphate/phosphocreatine
Creatine Kinase
- Enzyme that catalyzes synthesis of ATP from CP/PCr and ADP
- ADP + CP ATP + Creatine
How much ATP does the body store at any given time?
80-100 g (not much)
Can ATP be completely depleted?
No, too important to cellular function
Adenylate Kinase Reaction
- AKA myokinase reaction
- 2 ADP ATP + AMP
- Used to rapidly replenish ATP
Relationship between adenylate kinase reaction and glycolysis
This reaction acts as a stimulant for glycolysis
What acts as a control for the reactions of the phosphagen system?
Law of mass action (mass action effect)
Law of Mass Action (Mass Action Effect)
- Concentration of reactants or products (or both) in solution will drive the direction of the reactions
- If there’s an enzyme involved, enzyme concentration is also a major regulatory factor
Glycolysis
- Breakdown of glucose (carbs)
- Occurs in the cytosol of the cell
What is the end result of glycolysis?
Pyruvate
Pyruvate may proceed in which directions?
- Can be converted to lactate in the sarcoplasm (fast/anaerobic)
- Can be shuttled into the mitochondria (slow/aerobic)
Why is glycolysis limited in duration when pyruvate is converted into lactate?
H+ production and the subsequent decrease in pH
How is the direction for pyruvate determined?
The energy demands of the cell