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Questions and Answers
What is the primary function of glucose in the energy systems?
What is the primary function of glucose in the energy systems?
The ATP-PC system lasts longer than the anaerobic lactic system.
The ATP-PC system lasts longer than the anaerobic lactic system.
False
What is the byproduct of anaerobic glycolysis that causes muscle fatigue?
What is the byproduct of anaerobic glycolysis that causes muscle fatigue?
lactic acid
The Krebs cycle follows the conversion of pyruvate into __________.
The Krebs cycle follows the conversion of pyruvate into __________.
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Match the following energy systems with their characteristics:
Match the following energy systems with their characteristics:
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What happens to the Basal Metabolic Rate (BMR) after the age of 20?
What happens to the Basal Metabolic Rate (BMR) after the age of 20?
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Anabolism refers to the breaking down of compounds.
Anabolism refers to the breaking down of compounds.
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What is the role of ATP in the body?
What is the role of ATP in the body?
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After breaking down macronutrients, they are delivered through the ______.
After breaking down macronutrients, they are delivered through the ______.
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Match the following processes with their descriptions:
Match the following processes with their descriptions:
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Which hormone is known to increase BMR?
Which hormone is known to increase BMR?
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Exercise does not affect BMR.
Exercise does not affect BMR.
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What are the two stages of catabolism?
What are the two stages of catabolism?
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What is the primary location for ATP production during aerobic metabolism?
What is the primary location for ATP production during aerobic metabolism?
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Lactic acid is produced during aerobic metabolism.
Lactic acid is produced during aerobic metabolism.
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How many molecules of ATP are produced per molecule of glucose during aerobic respiration?
How many molecules of ATP are produced per molecule of glucose during aerobic respiration?
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Fat metabolism yields ____ calories of energy per gram.
Fat metabolism yields ____ calories of energy per gram.
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What is a common result of high sugar intake on metabolism?
What is a common result of high sugar intake on metabolism?
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Trained athletes reach a steady state of oxygen consumption faster than untrained individuals.
Trained athletes reach a steady state of oxygen consumption faster than untrained individuals.
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What happens to lactic acid during anaerobic activity after it is transported to the liver?
What happens to lactic acid during anaerobic activity after it is transported to the liver?
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What occurs during excess post-exercise oxygen consumption (EPOC)?
What occurs during excess post-exercise oxygen consumption (EPOC)?
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Muscle fatigue is primarily caused by the accumulation of lactic acid.
Muscle fatigue is primarily caused by the accumulation of lactic acid.
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At what percentage of VO2 max does the lactate threshold occur in untrained athletes?
At what percentage of VO2 max does the lactate threshold occur in untrained athletes?
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The preferred fuel source for the body during exercise is ___ .
The preferred fuel source for the body during exercise is ___ .
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Match the following terms with their definitions:
Match the following terms with their definitions:
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What is the crossover point in energy source selection during exercise?
What is the crossover point in energy source selection during exercise?
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High-intensity exercise primarily relies on aerobic metabolism.
High-intensity exercise primarily relies on aerobic metabolism.
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What physiological changes occur during recovery from high-intensity exercise?
What physiological changes occur during recovery from high-intensity exercise?
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Type 2 muscle fibers rely on enzymes that convert pyruvate to ___ .
Type 2 muscle fibers rely on enzymes that convert pyruvate to ___ .
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What is the effect of exercise duration on fuel selection?
What is the effect of exercise duration on fuel selection?
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Study Notes
Metabolism
- Defined as all chemical reactions where the body converts food into energy for survival
- Basal Metabolic Rate (BMR) is the rate at which the body uses energy while resting
- The body maintains blood flow, repairs tissues, digests food and regulates temperature
- Factors affecting BMR:
- Age: Decreases 2% per year after age 20
- Body Fat Percentage: Higher body fat percentage leads to lower BMR
- Gender: Women generally have a lower BMR than men
- Diet: Reduced food intake leads to a lower BMR to conserve energy
- Stress: Increases sympathetic response (fight or flight response), affecting BMR. Hormones like thyroxine and epinephrine increase BMR.
- Exercise: Catabolism of fat increases BMR, even during rest.
- Anabolism: Building compounds
- Catabolism: Breaking down compounds
- ATP: Immediate energy source for bodily functions like muscle contractions
- PCr: Resynthesizes ATP when energy is needed rapidly using a high-energy phosphate and ADP
- Cellular Respiration: Carbs and lipids are broken down into CO2 and H2O, releasing energy for ATP resynthesis
ATP (Adenosine Triphosphate)
- Phosphate, ribose (sugar) and adenine
- Immediate energy source, little stored in cells; provides energy for a few seconds
- Recycled continuously; total in body is approximately 3 ounces.
- ATPase: An enzyme that removes a phosphate from ATP, turning it back into ADP, releasing energy.
- Phosphorylation: Transferring phosphate to another molecule creates a bond that absorbs/stores energy.
- Oxidative Phosphorylation: A process in the mitochondria, creating ATP using oxygen.
Stages of Macronutrient Breakdown
- Stage 1: Macronutrients (carbohydrates, fats, proteins) are broken into smaller units (sugars, fatty acids, amino acids) and transported through the blood.
- Stage 2: These smaller units are broken down into CO2 and H2O in cells, releasing energy that powers the body's cells.
Energy Systems
-
Anaerobic: without oxygen
- ATP-PCr system: Uses stored ATP and PCr to power Type 2b muscle fibers; lasts 0-15 seconds (e.g., sprinting, shot put). PCr gets depleted during intense activity, ATP synthesis stops.
-
Anaerobic Lactic (Glycolysis): Breakes down glucose when ATP and PCr are depleted. Carbs broken down for ATP resynthesis. Occurs in Type 2a or 2b muscle fibers, lasts 15 seconds to 2 minutes (e.g., 400m run, basketball).
-
Lactic acid is a byproduct that builds in muscles during intense work and fatigue
-
Aerobic: with oxygen; most efficient
- Uses oxygen, releasing 38 molecules of ATP per glucose molecule; lasts 2 minutes - a few hours; Type 1 muscle fibers
Fat Metabolism
- 9 calories of energy per gram; good for prolonged exercise
- Broken down into fatty acids, glycerol, etc. (lipolysis).
- Converted into Acetyl CoA in the mitochondria for ATP production in the Krebs cycle
Protein Metabolism
- 20 different amino acids; 4.3 calories per gram
- Used when other energy sources are depleted
- Broken down into amino acids; some to pyruvate then acetyl CoA, Krebs cycle
- Not stored; fully functional in muscles.
Cori Cycle and Lactic Acid
- Lactic acid, a byproduct of anaerobic glycolysis, is transported to the liver.
- The liver converts lactic acid into pyruvate and then glucose to be used as energy. (Glucose → Pyruvate → Lactate)
Fuel Selection
- Carbs are the body's preferred fuel
- Influenced by diet, exercise intensity, and duration
- High-fat, low-carb diets use fats as main energy source.
- Exercise intensity shift from carbs to fats, crossover point
- Low intensity exercises: prioritize fats.
- High intensity exercises: use more carbs.
- ↑ duration = ↑epinephrine = ↑lipase activity = ↑lipolysis
Fat and Carb Metabolism
- Exercise exceeding 2 hours depletes glycogen stores, and aerobic ATP needs pyruvate from glycogen to function.
- Less pyruvate leads to decreased Krebs cycle function and lower ATP production
Body Fuel Sources
- Muscle glycogen, plasma glucose, fatty acids, and muscle triglycerides are the main fuel sources. The relative contribution of each source depends on exercise intensity
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Description
Test your knowledge on the primary functions of glucose, energy systems, and the metabolic processes involved in ATP production. This quiz covers the ATP-PC system, anaerobic glycolysis, and factors affecting Basal Metabolic Rate. Challenge yourself with questions on muscle fatigue, hormones, and the stages of metabolism.