Lecture 5 Skeletal Muscle

Lecture 5 Skeletal Muscle - + and K + channels) • AP...

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Lecture 5 Skeletal Muscle I. Skeletal Muscle Anatomy A.) Anatomy Muscle – made up of a bunch of muscle cells laid together in a parallel way Myofiber is an individual muscle cell Makes up 80-100% of entire length of muscle Has a bunch of nuclei 10-80 μm diameter 1 NMJ/fiber in middle Sarcomere – functional element from 1 z line to other z line At rest: 2 – 2.6 μ Myofibril (contains the sarcomere) – 1 μ diameter Myofilaments Actin (thin filaments) – 1 μ long, 7 nm diameter Myosin (thick filaments) – 1.6 μ long, 10-14 nm diameter Z line – actin attachment (titan attached also, not important for this class) A band – myosin and actin overlap I band – actin only “Striated muscle” B.) Structures in myofiber for spread of AP starting at NMJ 1.) Sarcolemma – membrane that is electrically active because they hold membrane potential across (contain Na
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Unformatted text preview: + and K + channels) • AP travels both ways because of NMJ 2.) Transverse tubules – T-tubules spread AP to sarcomeres • Extension of sarcolemma down to sarcomeres, right along z-lines in humans • AP must get to sarcomeres at the same time C.) Ca ++ storage/release • Sarcoplasmic Reticulum (SR) RyR – 1 ryanodine receptor (SR Ca ++ channel) DHPR dihydropyridine receptor (L-type Ca ++ channel in T-tubule membrane) o Voltage gated channel, amount of Ca++ coming in is not important for triggering contraction. What is important is when depolarization hits this voltage gated receptor; it goes through a conformational change. Changes conformation of associated proteins Associated proteins – connect changes in voltage gated channel to changing the state of opening up RyR...
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This note was uploaded on 07/21/2008 for the course BIPN 105 taught by Professor Armour during the Winter '08 term at UCSD.

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Lecture 5 Skeletal Muscle - + and K + channels) • AP...

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