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Questions and Answers
Why are triglycerides processed differently than proteins and carbohydrates after intestinal absorption?
Why are triglycerides processed differently than proteins and carbohydrates after intestinal absorption?
- Triglycerides are absorbed into the lymphatic system, allowing them to be distributed throughout the body before reaching the liver. (correct)
- Triglycerides are processed in the kidneys before entering the bloodstream.
- Triglycerides are absorbed into the portal vein and transported to the liver for initial processing.
- Triglycerides are directly transported to the liver for immediate processing, bypassing the lymphatic system.
During intense exercise when oxygen supply is limited, how does the body continue to produce ATP?
During intense exercise when oxygen supply is limited, how does the body continue to produce ATP?
- By converting acetyl CoA back into pyruvate to sustain the Krebs cycle.
- By converting pyruvate into lactic acid, which generates ATP without requiring oxygen. (correct)
- By increasing the rate of oxidative phosphorylation to maximize ATP production.
- By exclusively utilizing stored glycogen, bypassing the need for oxygen.
After a carbohydrate-rich meal, how does the body primarily store the excess glucose?
After a carbohydrate-rich meal, how does the body primarily store the excess glucose?
- By converting glucose into amino acids for protein synthesis.
- By converting glucose into glycogen, a stored, inactive form of glucose. (correct)
- By directly excreting excess glucose through urine.
- By converting glucose into triglycerides (fat) for long-term energy storage.
During energy production, at which point does glycerol from triglycerides enter the glucose metabolism pathway?
During energy production, at which point does glycerol from triglycerides enter the glucose metabolism pathway?
What is the primary role of oxidative phosphorylation (electron transport chain) in energy production?
What is the primary role of oxidative phosphorylation (electron transport chain) in energy production?
If the body lacks sufficient glucose, what happens to triglycerides, and how do their components enter the energy production pathways?
If the body lacks sufficient glucose, what happens to triglycerides, and how do their components enter the energy production pathways?
Which of the following statements accurately describes the metabolic fate of acetyl CoA?
Which of the following statements accurately describes the metabolic fate of acetyl CoA?
What is the immediate product of glucose conversion during energy production, and where does it proceed for further processing?
What is the immediate product of glucose conversion during energy production, and where does it proceed for further processing?
Flashcards
Amino Acids
Amino Acids
Proteins are broken down into these during digestion.
Glucose
Glucose
Sugars are broken down into this simple form for absorption.
Glycerol and Fatty Acids
Glycerol and Fatty Acids
Fats are digested into these two components
Glycogen
Glycogen
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ATP (Adenosine Triphosphate)
ATP (Adenosine Triphosphate)
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Oxidative Phosphorylation
Oxidative Phosphorylation
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Lactic Acid
Lactic Acid
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Ketones
Ketones
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Study Notes
Macronutrient Processing
- Proteins, fats (triglycerides), and carbohydrates are ingested, broken down through digestion, and further processed in the body.
- Macronutrients are initially digested in the stomach.
- Further digestion occurs in the intestines, breaking proteins into amino acids, sugars into glucose, and triglycerides into glycerol and fatty acids.
Nutrient Absorption and Transport
- Amino acids, glucose, glycerol, and fatty acids are absorbed into the portal vein and transported directly to the liver for processing.
- Unlike proteins and carbohydrates, triglycerides (as glycerol and fatty acids) are absorbed into the lymphatic system.
- The lymphatic system delivers triglycerides into the systemic circulation, allowing fats to be distributed throughout the body before reaching the liver.
Storage
- After a meal, the body stores amino acids as proteins, glucose as glycogen, and glycerol and fatty acids as triglycerides (fat).
- Glycogen is the stored, inactive form of glucose.
Energy Production (ATP)
- The body primarily uses glucose to produce energy (ATP).
- Glucose is converted into pyruvate, which enters the mitochondria and is converted into acetyl CoA.
- Acetyl CoA goes through the Krebs cycle (citric acid cycle), releasing carbon dioxide and ATP.
- A small amount of ATP is produced when glucose is converted to pyruvate.
Oxidative Phosphorylation
- Hydrogen, released during the conversion of acetyl CoA, interacts with oxygen and transmembrane proteins on the mitochondrial membrane.
- This process, called oxidative phosphorylation or the electron transport chain, produces a large amount of ATP (32-36 ATP molecules).
Anaerobic Respiration and Lactic Acid
- During intense exercise (e.g., a 100-meter sprint), oxygen may become a limiting factor in ATP production.
- Pyruvate is converted into lactic acid when oxygen is insufficient.
- Lactic acid production does not require oxygen and can still form ATP.
- Lactic acid buildup causes discomfort after intense, anaerobic exercise.
Triglyceride Metabolism Integration
- Glycerol and fatty acids, derived from triglycerides, can enter glucose metabolism at different points.
- Glycerol can enter the glucose chain at the pyruvate level.
- Fatty acids can enter glucose metabolism at the acetyl CoA level.
- Pyruvate can be converted back into glucose.
- Acetyl CoA cannot be converted back into pyruvate.
Ketone Production
- Without sufficient glucose, triglycerides are broken down for energy.
- Glycerol enters at the pyruvate level, and fatty acids enter at the acetyl CoA level.
- Oxaloacetate is used to convert pyruvate back into glucose to replenish glucose stores.
- Excess acetyl CoA is produced due to the influx of fatty acids.
- The excess acetyl CoA is converted into ketones, such as beta-hydroxybutyrate and acetone.
- Ketones can be used for ATP production.
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