UWL BIO 312 - Muscle mechanics, metabolism, and fiber type (2 pages)

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Muscle mechanics, metabolism, and fiber type



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Muscle mechanics, metabolism, and fiber type

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Lecture on the end of muscle mechanics, muscle metabolism, and the different types of muscle fibers


Lecture number:
21
Pages:
2
Type:
Lecture Note
School:
University of Wisconsin-La Crosse
Course:
Bio 312 - Human Anatomy and Physiology I
Edition:
1

Unformatted text preview:

Bio 312 Lecture 21 Lecture Outline I Muscle mechanics a Muscle twitch b Load velocity relationship c Load tension relationship II Muscle metabolism a Phosphagen system b Anaerobic pathway c Aerobic respiration III Fiber types Muscle Mechanics Muscle Twitch the mechanical contractile response to a single stimulus AP o Latent period between AP and development of external tension caused by Time needed to release enough Ca2 from sarcoplasmic reticulum Move tropomyosin cycle the cross bridges Series elastic component time it takes for elastic fibers to stretch and generate force o Twitch responses to different action potentials can summate o Tetanus tetanic summation AP s occurring at a fast enough rate to not let muscle relax at all o With increased stimulation frequency Ca2 in the sarcoplasm is persistently elevated allowing cross bridges to be active for a longer time o The series elastic componenet causes a dissociation between the tension generated directly by ross bridge activity within sarcomere internal tension and the external tension actually exerted on the afterload Elasticity of proteins and connective tissue in muscle fibers requires the muscle to be stretched before they can generate noticeable force on the afterload Length tension relationship tension force a muscle can produce from different resting lengths o Preload how stretched out a muscle is just prior to contraction o Optimum length is 100 of resting length allows for perfect overlap of cross bridges and thin filaments Under or overstretching does not allow for maximum amount of cross bridge thin filament connections Muscles will generally stay within 70 130 of their resting length o Titin elastic structural protein that keeps thick filaments aligned Prevents overstretching of sarcomere allows for elastic recoil after passive stretch Load velocity relationship as load on a muscle increases the speed at which that muscle can contract decreases with increase in load Will decrease until velocity



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