PSIO 201 5th Edition Lecture 21 Outline of Last Lecture Muscle MechanicsOutline of Current Lecture I. Muscle Energetics II. ATPIII. Creatine Phosphate PoolIV. Fatigue V. Cori CycleCurrent LectureThe Immediate source of energy to support development of tension : ATP1. hydrolysis by the myosin head group fuels tension generation2. Hydrolysis by the Ca-pump of the SR supports relaxationWhere does ATP come from?1. Cell “pool” of ATP – ATP is not stored only keeps enough to support 2 seconds of maximal force 2. Creatine Phosphate (CP) pool – stores high energy phosphate – CP pool has enough energy phosphate to last 15 seconds of maximal contractionCreatine Phosphate Pool –1. After meal: ATP + C ADP + CP2. During Exercise: ADP +CP ATP + CCreatine –These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Is a small amino acid like molecule that is synthesized in the liver, kidney, and pancreas and transported to muscle fibersIn a relaxed muscle fiber creatine is 3-6 more plentiful than ATPWhere does the ATP come from?3. Glycogen – storage form of glycose (used anaerobically) – occurs rapidly and in the cytoplasm- 2 minutes of contraction4. Glycogen – fat and protein used (aerobically) – occurs slowly and in mitochondria – can support 40 min to several hours of contraction (intensity dependent)Fatigue – Cost of Peak ActivityProgressive increase in the effort needed to maintain desired force; remain force in repetitive orcontained contractionsCan be psychological, muscle, nervous fatigueFatigue Problem Causes:1. Glycogen depletion2. Lactic and Buildup from anaerobic glycolysis 3. Phosphate build up from creatine phosphate metabolismCori Cycle - Muscle Lactic acid Liver GlucoseElevated O2 consumption after exercise: 1. Lactic acid conversion back to glycogen in the liver (Cori Cycle)2. Resynthesize creatine phosphate 3. Replace oxygen removed from myoglobin 4. Repair and
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