Muscle Physiology Flashcards
Frank-Starling mechanism
stroke volume of the heart increases in response to an increase in the volume of blood filling the heart
synchronization in muscle fibers
accomplished by;
- desmin, a linking protein between neighboring sarcomeres
- electrophysiological properties of the sarcolemma
- T-tubules
cross bridge cycle events
- myosin binds to actin
- releases Pi
- undergoes power stroke
- myosin detaches from actin when myosin binds ATP
myosin molecule
- hexamer: two heavy chains; four light chains
- globular head that binds ATP
- hydrolyses ATP
3 isoforms of myosin
-Type I, Type IIA, Type IIX
muscle anatomy
macro to micro: muscle, fascicle, muscle fiber, myofibril, sarcomere, myofilaments, thick filament, thin filament
excitation-contraction coupling
a. Involves ryanodine receptors
b. Involves Ca++ release channels found in the SR
c. Involves the release of Ca++ from the SR
d. Involves the binding of Ca++ to troponin-C
shortening
I and H bands shorten
costamere
A region/focal point that connects the cytoskeleton with the extracellular matrix.
-defects in costameres -> fragile sarcolemma
Duchene Muscular Dystrophy.
-affects dystrophin, a costamere
titin
-contributes to passive elastic properties
2 key proteins associated with the costamere
- dystroglycan
- sarcoglycan
motorneurons
- classified as S, FR, and FF
- recruited according to the size of the motorneuron
A band
length of the thick filament
perimysium
surround fascicles
