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Muscles - Anatomy & Physiology (view source)

Revision as of 10:03, 24 July 2008

629 bytes added , 10:03, 24 July 2008

→‎Skeletal Muscle

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***High '''glycolytic''' activity

***Function - exercise, bursts of activity

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*Muscle activation is initiated by a nervous impulse crossing the Neuromuscular Junction

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*'''Neurogenic Contraction''': Muscle activation is initiated by a nervous impulse crossing the Neuromuscular Junction to individual muscle fibers

**The neurotransmitter, '''Acetylcholine (Ach)''', binds receptors in the muscle fiber to open Na+ channels

**This causes a wave of depolarization along the sarcoplasmic membrane, further opening voltage-gated Na+ channels, which propagates the signal along the sarcolemma

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***This causes inhibition of the steric block keeping Actin and Myosin from interacting

*Increased Calcium causes a negative feedback inhibition of Ca release, and it is pumped back into the sarcoplasmic reticulum by the Ca/ATPase pump

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==Cardiac Muscle==

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*Structural: striated but uninucleate, highly vascularized

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*Gap junctions concentrated at intercalated discs

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**'''Myogenic Contraction''' spreads cell to cell and does not depend on nervous imput to individual cells

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**Areas of low electrical resistance allow rapid spread of action potentials

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**Contraction is regulated by autonomic neurons and circulating hormones

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*Contractile mechanism similar to skeletal muscle: increase cytosolic Ca

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**Ca influx across plasma membrane AND sarcoplasmic reticulum

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*Action potential has a prolonged plateau phase

==Smooth Muscle==

Bepocock

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