Muscles Flashcards
Role of muscles
supply force for movement
restrain movement (stabilize body)
control viscera
form sphincters that control the passage of materials
heat production
produce electricity
somatic muscle
attaches to the bone or cartilage
visceral muscle
attaches to organs, vessels, and ducts
voluntary muscle
under conscious control
involuntary muscle
not under conscious control
nucleate tell us
how many nucleo the muscle cell has
striated vs unstriated
striated filaments are aligned in rows
unstriated filaments are not aligned in rows
3 types of muscle
skeletal, smooth, and cardiac
Smooth muscle
unstriated, mononucleate, cells are joined in sheets that wrap around organs that they exert control over, cells are electrically coupled (can pass signal), visceral muscles and involuntary
skeletal muscle
voluntary, striated, multinucleate, filled with sarcomeres, attach to the skeleton but also surround the digestive and urinary tract
cardiac muscle
striated, multinucleate, branched, and joined by intercalated disks, waves of contraction are spread through intercalated disks
skeleton muscle actions
contract pulling on the skeleton to create movement
origin of muscle
attached to immobile part of bone
insertion of muscle
attached to the more mobile bone
antagonistic muscles
move skeletal elements in opposite directions, muscles can only create force in one direction via contraction so they are often paired as antagonistic sets
synergistic muscles
muscles that work together, multiple redundant muscles allow for each to reach peak force at different times (get around limitations)
skeletal muscle structure
composed of muscle bundles that contain multiple muscle cells (fibers), fascicles (muscle cells packed together) surrounded by epimysium, attached to bone via tendons
tendons
connective tissue surrounding muscle that extends to periosteum around bones, less energetically costly to maintain than muscle, allow long connection for short muscles
myofibrils
Composed of chains of repeating units called sarcomeres
z bands
separate sarcomeres
myofilaments
overlapping filaments in sarcomeres
myosin
thick filaments with protruding heads, heads are tilted to the side, have binding sites for ATP and actin, heads can hydrolyze ATP (releasing phosphate and energy) active during contraction
actin
thin filament with two other proteins attached
resting state of contraction
no stimulation from the nervous system, muscle is soft, shape maintained by collagenous fiber around it, not force generated, can be stretched