Lect17 - Jan27 - Muscle III

Lect17 - Jan27 - Muscle III - Muscle 1, 2 & 3 Isotonic...

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1/22/11 17 Muscle 1, 2 & 3 Isotonic Contraction – Graph of Relationship among sarcomere length, tension, and whole muscle length (movement of the load) Sarcomere and Whole Muscle Behavior During Isotonic Contraction 1 2 3 Tension Ext Sarcomere Length Resting Tension CE SE Muscle Contraction Contraction Sarcomere Shortening A M M M A M M M 1. Resting tension, sarcomere & muscle length. 2. Cross-bridge cycling, Sarcomere Shortening, Extension SE, & tension. No external shortening. 3. Continued sarcomere shortening. Tension = load. Sarcomere shortening now produces external shortening & shortening the whole muscle lifts the load. Stim to Contract 2 = Isometric Phase of an Isotonic Contraction. Maxwell Model of muscle contraction. Isotonic Contraction - CE used to stretch SE. Signal to contract muscle --> crossbridge formation and cycling --> sarcomere shortening --> development of tension through the SE, no change in muscle length, once develop enough tension to equal the load --> further sarcomere shortening --> whole muscle shortening and movement of the load contractile element = CE, Series Elastic Element = SE, Actin/ Myosin = A/M A/M interaction generates force by shortening the sarcomere and stretching the SE.
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1/22/11 18 Muscle 1, 2 & 3 Isometric Contraction – Relationship among sarcomere shortening, tension and whole muscle length (No shortening of the whole muscle & No movement of the load) LOAD HEAVY LOAD Resting Tension CE SE Muscle Contraction Relaxation 2 1. Resting Tension 2. Cross-bridge Cycling, Sacromere Shortening, Extension SE & Tension. All Sacromere Shortening ! Tension. No External Shortening or Shortening of the Whole Muscle. Stim 1 Tension Length Ext Sarcomere Sarcomere and Whole Skeletal Behavior During Isometric Contraction HEAVY Muscle working against a 50 pound load - resting tension and the amount of CE mobilized is the same as for the last example (isotonic). Sarcomere shortening --> SE extenstion --> continues until all CE is used in tension development. Same sarcomere shortening, no external shortening of he whole muscle.
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1/22/11 19 Muscle 1, 2 & 3 Contractile Properties of Whole Muscle 1. Relationship between Tension and Whole Muscle Shortening for an Isotonic Contraction RELATIONSHIP BETWEEN TENSION (LOAD) AND EXTERNAL SHORTENING ISOTONIC CONTRACTION DISSIPATION OF CONTRACTILE ENERGY: 1. ALWAYS IN INTERNAL, SARCOMERE SHORTENING.
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This note was uploaded on 08/21/2011 for the course NPB 101 taught by Professor Fuller,charles/goldberg,jack during the Winter '08 term at UC Davis.

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Lect17 - Jan27 - Muscle III - Muscle 1, 2 & 3 Isotonic...

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