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Muscles - Anatomy & Physiology (view source)
Revision as of 10:03, 24 July 2008
, 10:03, 24 July 2008→Skeletal Muscle
***High '''glycolytic''' activity
***High '''glycolytic''' activity
***Function - exercise, bursts of activity
***Function - exercise, bursts of activity
*Muscle activation is initiated by a nervous impulse crossing the Neuromuscular Junction
*'''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
**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
**This causes a wave of depolarization along the sarcoplasmic membrane, further opening voltage-gated Na+ channels, which propagates the signal along the sarcolemma
***This causes inhibition of the steric block keeping Actin and Myosin from interacting
***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
*Increased Calcium causes a negative feedback inhibition of Ca release, and it is pumped back into the sarcoplasmic reticulum by the Ca/ATPase pump
==Cardiac Muscle==
*Structural: striated but uninucleate, highly vascularized
*Gap junctions concentrated at intercalated discs
**'''Myogenic Contraction''' spreads cell to cell and does not depend on nervous imput to individual cells
**Areas of low electrical resistance allow rapid spread of action potentials
**Contraction is regulated by autonomic neurons and circulating hormones
*Contractile mechanism similar to skeletal muscle: increase cytosolic Ca
**Ca influx across plasma membrane AND sarcoplasmic reticulum
*Action potential has a prolonged plateau phase
==Smooth Muscle==
==Smooth Muscle==