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Lecture 8 1-30-08

Lecture 8 1-30-08 - I II III Ca Regulation of Muscle...

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I. Ca ++ Regulation of Muscle Contraction a. Ca++ Effect i. Tropomyosin/ Troponin ect. b. Ca++ Availability i. Ca++ Storage 1. extracellular fluid 2. Sarcoplasmic Reticular (SR) (Figure 49.32) a. Large store of calcium in the myofibril b. Source of calcium when we need the muscle to contract quickly 3. Pic 1 ii. Ca++ Release (Figure 49.33) 1. NMJ: EPSP in muscle a. AP 2. AP invades T-tubules increase Vm released by Ca+ into cytoplasm (Ca++ came from SR and a little from outside the voltage gated calcium channels) 3. Ca+ binds to troponin and initiates contraction 4. after AP has passed, Vm decreases and after repolarization then Ca+ pumps return Ca__ to the source a. Most of it came from the SR II. Muscle Physiology a. Twitch: arises from a single stimulus of the motor nerve producing brief contraction. (e.g. Skeletal muscle also known as fast twitch muscle) i. Pic 2 1. Bundle axons have to stimulate them all 2. As you increase the amount of stimulation increase the number of axons stimulated
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