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Physiology 12Physiology 12

MuscleMuscle

Germann Ch 8 Reflexes & Voluntary Motor

ControlCh. 11

There are three types of muscle in There are three types of muscle in the Human bodythe Human body

SkeletalSkeletalCardiacCardiacSmoothSmooth

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Skeletal Muscle Skeletal Muscle

Function: To deliver force to the boneFunction: To deliver force to the bone

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Cylindrical SkeletalCylindrical Skeletal--muscle Fibersmuscle Fibers

Organization of Skeletal MuscleOrganization of Skeletal Muscle

Muscle Muscle FasiciculusFasiciculus –– bundle of muscle fibersbundle of muscle fibersMuscle Fibers Muscle Fibers –– Individual multinucleated cell of Individual multinucleated cell of muscle (with structures analogous to cell muscle (with structures analogous to cell biology)biology)

SarcolenmaSarcolenma = cell membrane= cell membraneSarcoplasmSarcoplasm = Cytoplasm= CytoplasmSarcoplasmicSarcoplasmic Reticulum = Endoplasmic ReticulumReticulum = Endoplasmic ReticulumT tubule systemT tubule systemMitochondriaMitochondria

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Where does the force Where does the force come from ?come from ?

Molecular action of the Molecular action of the SarcomereSarcomere

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Intertwined helical chains of Intertwined helical chains of actinactinmoleculesmolecules

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Myosin FilamentMyosin Filament

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Cross bridging cycleCross bridging cycle

What regulates muscle contraction?What regulates muscle contraction?

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Can we get more control over the Can we get more control over the contraction of an individual muscle contraction of an individual muscle

fiber?fiber?

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There are a lot of muscle There are a lot of muscle fibers in each muscle, fibers in each muscle, differences in muscle differences in muscle

tension are produced via tension are produced via induction of different induction of different

motor units. motor units.

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Two types of contractionTwo types of contraction

Isometric = Contraction producing an increase Isometric = Contraction producing an increase in tension with out a change in muscle length in tension with out a change in muscle length

Isotonic = Contraction against a constant load Isotonic = Contraction against a constant load where muscle ends change lengthwhere muscle ends change length

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The length of a muscle The length of a muscle influences how much influences how much

total force it can generatetotal force it can generate

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Skeletal muscles must be supplied Skeletal muscles must be supplied with ATP for proper contraction.with ATP for proper contraction.

Muscle fibers come in different types Muscle fibers come in different types based on their composition of based on their composition of myosin fibers and metabolismmyosin fibers and metabolism

Slow oxidative fibersSlow oxidative fibersFast oxidative fibersFast oxidative fibersFast Fast glycolyticglycolytic fibersfibers

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Muscle fatigueMuscle fatigue

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Fatigue is not due to lack of ATP. Fatigue is not due to lack of ATP. The muscle is turned off by other The muscle is turned off by other mechanisms before the ATP runs mechanisms before the ATP runs

out.out.

Failure of T tubule systemFailure of T tubule systemBuild up of lactic acidBuild up of lactic acidCentral command FatigueCentral command Fatigue

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Smooth MuscleSmooth Muscle

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