muscular system midterm2

smooth muscle

involuntary muscle found in hollow organs and vessels

cardiac muscle

involuntary muscle found in the heart

skeletal muscle

voluntary muscle that is attached to the skeleton

tendon

connective tissue that connects muscle to bone

origin

attachment of a muscle on a stationary bone

insertion

attachment of a msucle on a bone that moves

agonist

the muscle that does most of the work

synergist

assists the agonist

antagonist

the muscle that acts opposite to a prime mover

sarcolemma

plasma membrane of muscle fibers

sarcoplasm

the cytoplasm of muscle fibers

myoglobin

red pigment that binds oxygen

fascicles

muscle fibers are arranged in bundles called

myofibrils

smaller cylinders that are grouped inside the larger cylindrical muscle

myofilaments

small cylinders that make up myofibrils that run along the length of the fiber; made up of proteins (actin and myosin)

sarcomeres

the repeating units of actin and myosin found along a myofibril

myosin

thick filaments shaped like a golf with the straight portion of the molecule ending in a globular head or cross-bridge

actin

thin filaments that make up myofilaments

ATP hydrolyzed

when myosin head is unattached

ADP+P bound to myosin

as myosin head attaches to actin

ADP+P release

causes head to change position and actin filament to move

binding of ATP

causes myosin head to return to resting position

motor unit

a nerve fiber and all of the muscle fibers it stimulates

muscle twitch

a single contraction lasting a fraction of a second

summation

an increase in muscle contraction until the maximal sustained contraction is reached

tetanus

maximal sustained contraction

glycogen and fat

fuel for muscle contraction stored in the muscle

glucose and fatty acids

fuel for muscle contraction stored in the blood

creatine phosphate pathway

fastest way to acquire ATP but only sustains a cell for seconds; builds up when a muscle is resting

fermentation

fast acting but results in lactate build up; anaerobic

cellular respiration

best long term source of ATP

fast twitch fibers

rely on creatine phosphate and fermentation pathways; contract quickly but more susceptible to fatigue; fewer blood vessels; no/little myoglobin

slow twitch fibers

rely on aerobic respiration; designed for endurance; contract slowly but have high endurance; myoglobin; many blood vessels