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M04.05.04 Cross-Bridge Interactions (Chemical-Mechanical Transduction)
Energy Sources for Muscle Contraction
Points to Remember:
- Muscle cells require a constant supply of energy to maintain contraction and relaxation cycles.
- ATP (adenosine triphosphate) is the primary energy currency in muscle cells.
Table 1: Energy Sources for Muscle Contraction
| Energy Source | Description |
|---|---|
| ATP | Immediate source of energy for muscle contractions |
| Creatine phosphate | Provides a rapid source of ATP through the creatine kinase reaction |
| Glycogen | Stored form of glucose in muscle cells, used in both anaerobic and aerobic metabolism |
| Glucose | Derived from blood and glycogen, used in glycolysis and oxidative phosphorylation |
| Fatty acids | Used primarily in aerobic metabolism, particularly during prolonged exercise |
Aerobic vs. Anaerobic Metabolism
Points to Remember:
- Aerobic Metabolism: Requires oxygen, produces more ATP, and is used during prolonged, low-intensity activities.
- Anaerobic Metabolism: Does not require oxygen, produces ATP quickly, and is used during high-intensity, short-duration activities.
Table 2: Aerobic vs. Anaerobic Metabolism
| Metabolism Type | Oxygen Requirement | ATP Yield | Byproducts | Primary Use |
|---|---|---|---|---|
| Aerobic | Yes | High (30-32 ATP per glucose) | Carbon dioxide, water | Endurance activities |
| Anaerobic | No | Low (2 ATP per glucose) | Lactic acid | Short bursts of intense activity |
Creatine Phosphate System
Points to Remember:
- The creatine phosphate system provides a rapid means of regenerating ATP from ADP.
- Creatine phosphate donates a phosphate group to ADP to form ATP, catalyzed by the enzyme creatine kinase.
Glycolysis and Oxidative Phosphorylation in Muscle
Points to Remember:
- Glycolysis: Occurs in the cytoplasm, and breaks down glucose into pyruvate, producing 2 ATP molecules per glucose. In anaerobic conditions, pyruvate is converted to lactic acid.
- Oxidative Phosphorylation: Occurs in the mitochondria, and involves the electron transport chain and chemiosmosis, producing up to 30-32 ATP molecules per glucose.
Table 3: Glycolysis vs. Oxidative Phosphorylation
| Process | Location | Oxygen Requirement | ATP Yield | Byproducts |
|---|---|---|---|---|
| Glycolysis | Cytoplasm | No | 2 ATP per glucose | Lactic acid (anaerobic) |
| Oxidative Phosphorylation | Mitochondria | Yes | 30-32 ATP per glucose | Carbon dioxide, water |
Bibliography
- Guyton, A.C., & Hall, J.E. (2020). Textbook of Medical Physiology (13th ed.). Saunders.
- Boron, W.F., & Boulpaep, E.L. (2016). Medical Physiology (3rd ed.). Elsevier.
- Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., & Walter, P. (2014). Molecular Biology of the Cell (6th ed.). Garland Science.
- McArdle, W.D., Katch, F.I., & Katch, V.L. (2015). Exercise Physiology: Nutrition, Energy, and Human Performance (8th ed.). Lippincott Williams & Wilkins.