Skeletal Muscle Physio Flashcards
Sliding Filament Mechanism
Actin and Myosin Filaments slide in between each other.
Ca2+ and ATP role in contraction
CA2+ for crossbridge cycle
ATP needed or rigor
Excitation Coupling Steps
Action Potentials Depolarization T -Tubules Inc Intracellular Ca2+ Ca2+ binds troponin C -Cross bridge Cycle begins Relaxation Dec. Intracellular Ca2+ Ca2- Released
Types of Muscular Contractions
Isotonic - tension constant, length changes
Concentric - muscle shortens T>L
Isometric - muscle prevented from shortening T=L
Eccentric - lengthening to create action T<L
Effect of resting fiber length on muscular contraction
There are upper and lower limits on stretch and shortening. limited performance.
Mechanism by which skeletal muscle can vary the amount of tension
motor unit recruitment
Summation v Recruitement
Summation - another AP start before action ends
Recruitment - Size principle - choosing some motor units over others
ATP production in skeletal muscle - pthwy
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Skeletal Muscle Fibers types + Characteristics
Type I - oxidative - Inc. myoglobin - least fatigueable
Type IIA - oxidative
Type IIB - glycoltic - Dec Myoglobin - easily fatigue
I before IIA before IIB
Skeletal Muscle Disorders
There are agents/disease that alter ACH release, reception and activation
Crossbridge Cycle - pthwy
ATP binds to myosin
Conf. Change = Myosin releases Actin
Myosin moves to + end actin and attaches (power stroke)
repeats cycle
LOW Ca2+ = no cross bridge cyles
NO ATP but calcium present = Rigor mortis
Myosin bound to actin permanently
Tetanus
Muscle doesn’t complete relaxation
Constant Ca2+ - broken gate
Malignant hyperthermia
Myasthenia Gravis
Self-produces antibodies that inactivate Ach
