Musculoskeletal System Flashcards
muscle
specific tissue w/i body that generates mechanical force in response to NS motor output; afferent message to brain to effect message that stimulates muscles for motor output
3 types of muscle in vert
skeletal, smooth, cardiac
skeletal muscle
responsible for movements of skeleton; muscles attached to bones via tendons; tough cords made of connective tissue
muscle fiber
long, cylindrical multinucleated cell; several cels fused together to create fiber in dev; T-tubules, sarcoplasmic reticulum, characterized by myofibrils
T-tubules
infoldings of pm
sarcoplasmic reticulum (SR)
specific ER in muscle fibers
myofibrils
long fiber w/i muscle fibers, run lenthwise; 2 types of filaments: thin and thick
thin filament
2 strands of actin; contractile protein w myosin binding sites; regulatory proteins: tropomyosin, troponin
thick filament
about 350 myosin contractile protein molecules; each w head (stick out from molecule) and tail (associate w each other, thickness)
actin + myosin
found in many cells but only highly organized in muscle cells; filament arrangement in muscle cells give “striped” appearance;; skeletal muscle = striated
sarcomere
basic unit of contraction w/i myofibrial; repeated unit of overlapping thin/thick filaments; lots of sarcomeres lined up end to end = myofibril = lots of muscle; made of z-lines and m-lines
z-lines
location where thin actin filaments are attached; join adjacent sarcomeres together @ their ends
m-lines
location of thick myosine filaments; anchored in middle
during muscle contraction
think actin + thick myosin filaments slide past one another need connections to each other: some old connections break, some new connections form; overall result = sarcomere gets shorter: distance btwn z lines going to shorten, length of filaments does not change only amnt of over changes
muscle fiber @ rest
trophomyosin covers myosin binding site along the thin actin filament
