muscles generate ✔️✔️motion, force, and heat
the 3 types of muscles are ✔️✔️skeletal, cardiac, and smooth muscles
skeletal and cardiac muscles are ✔️✔️striated muscles
skeletal muscles are controlled by ✔️✔️somatic motor neurons
cardiac and smooth muscle are controlled by ✔️✔️autonomic innervation, paracrines, and hormones
come smooth and cardiac muscles are ✔️✔️auto rhythmic and contract spontaneously
skeletal muscles are (not always) attached to ✔️✔️bones and tendons
the origin is ✔️✔️the end of the muscle attached closest to the trunk or to the more stationary bone
the insertion is the more ✔️✔️distal or mobile attachment
at a flexible joint ✔️✔️muscle contraction moves the skeleton
flexors bring ✔️✔️bones closer together
extensors move ✔️✔️bones away from each other
flexor-extensor pairs are ✔️✔️examples of antagonistic muscle groups
, a skeletal muscle is a collection of ✔️✔️muscle fibers and large cells with many nuclei
t tubules allow ✔️✔️action potentials to move rapidly into the interior of the fiber and reeler calcium
from the sarcoplasmic reticulum
myofibrils are ✔️✔️intracellular bundles of contractile and elastic proteins
thick filaments are made of ✔️✔️myosin
thin filaments are made mostly of ✔️✔️actin
titin and nebulin hold ✔️✔️thick and thin filaments
myosin binds to ✔️✔️actin, creating crossbridges between the thick and thin filaments
one sarcomere is composed of ✔️✔️two Z disks and the filaments between them
a sarcomere is divided into ✔️✔️I bands, A bands, and H zone
I bands ✔️✔️thin filaments only
A bands ✔️✔️runs the length of thick filament
(central) H zone ✔️✔️occupied by thick filaments only
the M line and Z disks represent ✔️✔️attachment sites for myosin and actin