Chapter 3 Flashcards
(18 cards)
How is ATP replenished by ADP?
ATP is replenished through three energy systems:
* Creatine phosphate System (ATP-PCr System)
* Anaerobic Glycolysis
* Aerobic (Oxidative) System
ATP is the primary energy currency of the cell, released when ATP is broken down to ADP and inorganic phosphate (Pi) during muscular contraction.
What is the predominant energy system during very high-intensity, short-term exercise?
The ATP-PCr System is the predominant energy source, providing immediate energy using stored ATP and creatine phosphate (PCr) for maximal efforts lasting ~10-15 seconds.
This system operates anaerobically and supports activities like sprints and jumps.
How is creatine rephosphorylated after its use in skeletal muscle?
Creatine is rephosphorylated during recovery when aerobic metabolism produces ATP through the reaction: ATP + Creatine → Phosphocreatine (PCr) + ADP, facilitated by creatine kinase.
This process occurs after intense exercise and requires oxygen.
What are the best uses for creatine supplementation?
Creatine supplementation is useful for:
* Short-duration, high-intensity activities
* Team sports with repeated bursts of intensity
* Resistance training
It improves muscle strength and hypertrophy.
What is the suggested supplementation regimen for creatine?
Suggested regimen:
* Loading Phase: 20-25g/day for 5-7 days
* Maintenance Phase: 3-5 g/day for 1 month
* Alternative Approach: 3-5 g/day continuously
Co-ingestion with carbohydrates may increase uptake.
What is the predominant energy system during high-intensity exercise lasting 1 to 2 minutes?
The Anaerobic Glycolytic System is the primary energy source, relying on glucose or glycogen breakdown for ATP production without oxygen and producing lactic acid as a byproduct.
Key limitation: lactate accumulation leads to muscle fatigue.
Is glucose in the muscle available for the regulation of blood glucose?
No, muscle cells lack glucose-6-phosphatase, preventing stored glucose from being released into the bloodstream.
Muscle glycogen fuels exercise but cannot contribute to blood glucose levels.
What are the fates of lactate produced during anaerobic glycolysis?
Fates of lactate include:
* Converted back to pyruvate for energy production
* Transported to the liver for gluconeogenesis (Cori Cycle)
* Used by the heart and other tissues
* Eliminated in sweat and urine
Lactate plays a significant role in energy metabolism.
What is the predominant energy system during moderate-intensity, long-term exercise?
The Aerobic (Oxidative) System is the primary energy system, using carbohydrates, fats, and sometimes proteins to produce ATP in the presence of oxygen.
It is the most efficient but slowest energy system.
What does VO₂max represent?
VO₂max represents the maximum amount of oxygen the body can utilize during intense exercise, indicating cardiorespiratory fitness and aerobic endurance capacity.
Measured in mL of oxygen per kg of body weight per minute.
Why does it take a few minutes for oxygen consumption to rise during aerobic exercise?
An oxygen deficit occurs because the cardiovascular system and mitochondria take time to increase oxygen delivery and aerobic ATP production.
Energy during this period comes from the phosphagen system and anaerobic glycolysis.
What are the phases of oxidative phosphorylation?
Phases of oxidative phosphorylation:
* Substrate prepared
* Krebs Cycle
* Electron Transport Chain (ETC)
Produces ~36 ATP per glucose molecule, more efficient but slower than glycolysis.
Why does oxygen consumption remain elevated after exercise?
Oxygen consumption stays high due to Excess Post-Exercise Oxygen Consumption (EPOC), replenishing ATP and creatine phosphate stores, clearing lactate, and restoring homeostasis.
Higher-intensity exercise results in greater EPOC.
Why are proteins not a preferred fuel source compared to carbohydrates and fats?
Proteins are slow and inefficient for energy production, produce nitrogen waste, and are essential for other functions.
Carbohydrates and fats provide ATP more efficiently.
Compare carbohydrates and fats as fuel sources for exercise.
Carbohydrates:
* ~36 ATP/glucose
* Fast energy
* Limited storage
* Preferred for high intensity
Fats:
* ~129 ATP/fatty acid
* Slow energy
* Unlimited storage
* Preferred for low-intensity
Carbs are quick fuel; fats are long-term fuel.
What happens to carbohydrates, fats, and proteins in energy balance during the fed state?
In the fed state:
* Carbohydrates → Stored as glycogen or converted to fat
* Fats → Stored in adipose tissue
* Proteins → Used for repair, excess converted to fat.
In energy balance, intake matches output.
What happens to carbohydrates, fats, and proteins in energy balance during the postabsorptive state?
In the postabsorptive state:
* Carbohydrates → Liver releases glucose
* Fats → Broken down for energy
* Proteins → Minimal breakdown, but muscle protein used in prolonged fasting.
This process helps maintain energy balance between meals.
