skeletal muscle is made of (3)

dense regular connective tissue surrounding entire muscle

Fibrous connective tissue surrounding fascicles

fine areolar connective tissue surrounding each muscle fiber

densely packed, rodlike elements

smallest contractile unit of a muscle fiber

composed of 2 interwoven heavy polypeptide chains as tails, and 2 light polypeptide chains as heads

myosin heads contain: (3)

Thin filaments contain

Thick filaments contain

network of smooth endoplasmic reticulum surrounding each myofibril

penetrate the cells interior at each A band- I band junction, part of triad

generation of force, can cause shortening of fiber

what is released from troponin?

binds to receptors in the sarcolemma

Na+ channels close and voltage-gated k+ channels open

muscle changes in length

muscle neither shortens nor lengthens

muscle shortens and does work

muscle contracts as it lengthens

force is not based on:

fast, fatiguable fibers

slow, fatiguable-resistant fibers

spindle shaped cells, no striations, involuntary control, one nucleus

found in walls of hollow organs of respiratory, digestive, urinary, and reproductive tracts as well as walls of arterioles

found in heart

striated, has intercalated disc, involuntary

voluntary muscle, has striations

Origin: immobile

Isertion: mobile

Runs the entire length of an A band

Runs the entire length of an I band and partway into the A band

coin-shaped sheet of proteins that anchors the thin filaments and connects myofibrils to one another

lighter midregion where filaments do not overlap

line of protein myomesin that holds adjacent thick filaments together