Week 6 - Energy System and Exercise I Flashcards
What is ATP and why is it important for the body?
- Energy currency of the body
- Food energy converted to ATP for energy supply
What are the classifications of energy systems?
- Anaerobic (nonaerobic): oxygen independent, can happen without oxygen
- Aerobic: oxygen dependent
What is the Immediate (alactic) Anaerobic system?
It uses
- ATP stores
- Phosphocreatine
- Adenylate kinase reactions
What are the 3 energy systems for ATP synthesis?
- Phosphate (immediate, ATP PC)
- Lactate (short-term, glycolytic system)
- Aerobic (long-term)
How do energy systems differ in ATP delivery?
- The duration of time they can maintain supply ATP
- The rate at which they can supply ATP
What is the substrate and product of Phosphate?
Substrate: phosphocreatine
Product: ATP + creatine
What is the substrate and product of Lactate?
Substrate: Stored sugar (glucose)& blood
Product: ATP + lactic acid
What is the substrate and product of Aerobic?
Substrate: Stored sugar & blood sugar/fat
Product: ATP + CO2
What is the substrate for ATP production in the Phosphate System?
Creatine phosphate
How does the Phosphate System produce ATP for muscle contraction?
Creatine phosphate donates a phosphate group to ADP to form ATP, which can be used for muscle contraction
What happens when a muscle contracts in the Phosphate System?
Phosphate group is cleaved off, forming phosphate and ADP again
How is ATP continually regenerated in the Phosphate System?
As long as there is sufficient creatine phosphate, ADP can be recycled to regenerate ATP
How much ATP does the Phosphate System supply?
It supplies a small quantity of ATP before exhausted
Where is the Phosphate System located in the cell?
Cytoplasm (not mitochondria)
Is the Phosphate System oxygen-dependent?
No, it is anaerobic (nonaerobic)
How is the Phosphate System regulated?
It is regulated by the ATP:ADP ratio
What is the reaction for ATP production in the Phosphate System?
PCr + ADP ↔ Cr + ATP (↔ = creatine kinase)
What happens in the Adenylate Kinase Reaction during exercise?
ATP breaks down into Pi + ADP
What happens when two ADP molecules bind together in the Adenylate Kinase Reaction?
They form ATP and AMP (adenosine monophosphate)
When does the Adenylate Kinase reaction occur?
Happens during recovery from exercise
What are the key situations where the ATP-PC (alactic) Immediate Energy System is relied upon?
- Initiation of physical activity
- Sudden increase in activity level
- For high intensity tasks
- If maximal effort or task only lasts 10-15 seconds
What type of reaction is the Lactate System?
Multi-step (10 step) reaction, a little slower than the ATP PC system
How does the Lactate System compare to the ATP-PC system in terms of ATP production?
The Lactate System provides ATP quickly (second fastest source) and has a much greater ATP capacity than the Phosphate System. It can last longer as well
What is the chemical process used in the Lactate System?
Glycolysis
Is the Lactate System oxygen-dependent?
No, it is anaerobic (nonaerobic)
What products does the Lactate System produce?
It produces pyruvic acid and/or lactic acid
What happens to pyruvate in the presence of oxygen?
If oxygen is present, pyruvate enters the Krebs cycle and is oxidized
What happens to pyruvate when oxygen is not present?
Without oxygen, pyruvate is converted to lactic acid, which then circulates to the liver to be metabolized (a slower process)
What is the role of Phosphofructokinase (PFK) in the Lactate System?
Phosphofructokinase regulates glycolysis
What is the role of Lactate Dehydrogenase (LDH) in the Lactate System?
Lactate Dehydrogenase (LDH) regulates lactate synthesis and controls the conversion of pyruvate to lactate. It is key in anaerobic training adaptations
What is the starting point of glycolysis in the Lactate System?
Glycolysis starts with glucose or glycogen, which is then converted to phosphofructokinase
What role does NADH play in glycolysis?
NADH is involved in glycolysis by donating hydrogen ions to the electron transport chain
What is the role of Lactate Dehydrogenase in the Lactate System?
Lactate Dehydrogenase facilitates the conversion of pyruvate to lactate and can also convert lactate back to pyruvate
What is the end product of glycolysis in the Lactate System?
Pyruvic acid
What are the two possible fates of pyruvate in the Lactate System?
- It can be used aerobically in the Krebs cycle (slow glycolysis)
- It can be converted to lactate (fast glycolysis)
Why is aerobic use of pyruvate slower than conversion to lactate?
Aerobic use in the Krebs cycle is slower because glycolysis occurs in the cytosol, while the Krebs cycle takes place in the mitochondria, requiring more time
What enzyme is key in determining the conversion of pyruvate to lactate?
Lactate dehydrogenase
What happens when there is a large and rapid demand for ATP?
The body produces lactate as pyruvate builds up quicker than slow glycolysis can remove it and shuttle it to the mitochondria for oxidation. This is known as “fast glycolysis.”
How do low oxygen levels in tissue affect pyruvate conversion?
Low oxygen levels, due to factors like altitude, respiratory disease, anemia, or reduced blood flow (e.g., isometric exercise), lead to less oxygen available to convert pyruvate aerobically, increasing lactate production
What factors lead to pyruvate production exceeding the Krebs cycle’s capacity to use pyruvate?
Low aerobic ATP synthesis capacity and high-intensity activity can overwhelm the Krebs cycle, leading to pyruvate being converted to lactate
When does the Lactate System provide energy?
It provides energy during high-intensity activity (>10 seconds) and supplements aerobic ATP supply during higher intensity physical activity (PA), including aerobic activities
When can blood lactate accumulate in everyday tasks?
Blood lactate can accumulate during everyday tasks in individuals with low aerobic fitness or compromised cardiovascular/respiratory systems
What is the Aerobic System’s role in ATP synthesis?
It is the slowest ATP source but supplies the largest amount of ATP
What substrates are used in the Aerobic System for ATP synthesis?
Carbohydrates, fatty acids, and sometimes amino acids
Where does Aerobic ATP synthesis occur?
In the mitochondria of cells
What is the common entry point for substrates in Aerobic ATP synthesis?
Acetyl-CoA, which can also be derived from amino acids
What role do NADH and FADH2 play in ATP synthesis?
They transfer protons (H+) to the electron transport chain (ETC) and are co-regulators of key enzymes
What happens during the Electron Transport Chain (ETC)?
Co-enzymes (NADH and FADH2) are oxidized, electrons are transferred to oxygen, producing water and ATP
What are the common entry points for the catabolism of carbohydrates, fats, and amino acids in ATP synthesis?
The common entry point is Acetyl-CoA
What happens in the catabolism of carbohydrates (CHO)?
Carbohydrates provide ATP more quickly through glycolysis, especially during high-intensity activities (e.g., less than 2 minutes). Fatty acids produce more ATP in the Krebs cycle and ETC, especially for longer, lower-intensity activities
What is the Aerobic System’s energy contribution?
It is always active, dominant at rest, and during low to moderate-intensity activity, providing energy for most everyday tasks and prolonged activities
What factors contribute to physical fatigue?
Low ATP and CP stores, low glycogen stores in muscles, low enzyme activity levels, low lactate tolerance, and limited mitochondria
What happens during recovery from exercise regarding ATP and lactate?
ATP is replenished aerobically and used to regenerate CP stores.
Lactate is converted back to pyruvate and used aerobically in muscles, transported to cardiac muscle, kidney, and liver for conversion to glucose via the Cori cycle
How can lactate levels be reduced quickly during recovery?
Low-intensity aerobic activity (cool down) increases the conversion of lactate to pyruvate in muscles
What is Oxygen Deficit?
It occurs at the onset of exercise when the aerobic system takes time to increase ATP production. ATP initially comes from ATP stores and the PC system
What is EPOC (Excess Post-Exercise Oxygen Consumption)?
It refers to the oxygen consumed after exercise to repay the “oxygen debt” and regulate processes that demand oxygen
What is the difference between the Fast and Slow Components of EPOC?
Fast component: reflects ATP-PC system replenishment
Slow component: reflects elevated body temperature, thermogenic hormone effects, and cardiovascular/respiratory system responses
How is EPOC related to fat burning?
Large EPOCs are associated with high-intensity and long-duration exercises, contributing to post-exercise fat burning. It’s more common in fit individuals or elite athletes
