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Unformatted text preview: sol back into cisternae cytosol 2+ • Ca2+ dissociate from troponin & also pumped back into SR dissociate • Tropomyosin moves back to block active site Muscle returns to resting length by 2 forces: recoiling from Muscle series-elastic components & contraction of antagonistic muscle(s) muscle(s) Length-tension relationship= amount of force produced by a muscle depends on how stretched/contracted it is BEFORE stimulated BEFORE • Weak= overly contracted (thick already close to Z-line) or overly overly stretched (little overlap of thick & active sites) overly • Strong= optimum resting length is in middle Behavior of Whole Muscles (cont.) Behavior Muscle tone= partial contraction maintained by CNS, allows for partial optimum muscle length so when stimulated, max action possible possible • Elastic filaments help to maintain optimal thick & thin overlap Threshold= minimum voltage needed to generate AP in muscle minimum fiber to produce contraction fiber • Triggers release of Ca2+ & activates sliding mechanism Twitch= a cycle of contraction & relaxation Latent period= delay period btw stimulus & twitch (~2 msec) delay where excitation, excitation-contraction, & tensing of serieswhere elastic components occur • Unseen internal tension occurring @ this time Unseen internal • Then external tension produced & movement observed Then external (contraction phase) (contraction Isometric & Isotonic Contraction Isometric Relaxation phase= [Ca2+] decreases as it’s pumped back into decreases SR, myosin heads release actin filaments, & so, muscle tension declines tension Contraction= producing internal tension (w/o shortening) &/or producing external tension (shortening of fibers) external 2 kinds of contraction: isometric-vs-isotonic (& 2 forms of kinds isometric isotonic: concentric-vs-eccentric) concentric • Isometric= contraction w/o change in length (cellular level) • Isotonic= contraction w/ change in length; internal tension now contraction strong enough to overcome resistance of ‘load’ strong • Concentric= muscle shortens as it maintains tension (box up) • Eccentric= muscle lengthens as it maintains tension (box down) muscle lengthens ATP Sources ATP ATP synthesis requires organic energy (glucose, fatty acids) ATP & O2 • Aerobic respiration= produces more (36) ATP, CO2 & H2O end products, but REQUIRES O2 end , • Anaerobic fermentation= ‘w/o O2’’, produces few (2) ATP, toxic end product (lactic acid) toxic Resting muscles make ATP from fatty acids mostly (glucose oxidation most common means elsewhere in body) oxidation • During exercise, mechanisms of making ATP change w/ During duration of activity (& availability of molecules) duration • Immediate, short-term, long-term energy Immediate- sprints, etc. use the O2 of myoglobin to make sprints, use myoglobin ATP (P+ADP= ATP) ATP • P transfer by 2...
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This note was uploaded on 01/12/2014 for the course ZOO 250 taught by Professor Staff during the Fall '08 term at S.E. Louisiana.

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