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33 terms

Chapter 9.

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excitability
the ability to receive and respond to a stimulus, that is, any change in the environment inside or outside the body.
contractility
the ability to shorten forcibly when adequately stimulated
extensibility
the ability to be stretched or extended
elasticity
the ability of a muscle cell to recoil and resume its resting length after being stretched
epimysium
an "overcoat" of dense irregular connective tissue that surrounds the whole muscle. It means "outside the muscle"
perimysium
surrounds each fascicle "around the muscle"
fascicle
muscle fibers are grouped resembles a bundle of sticks within each skeletal muscle
endomysium
"within the muscle" whispy sheath of connective tissue that surrounds each individual muscle fiber.
insertion
moveable bone
origin
immovable bone
direct attachment
epimysium of the muscle is fused to the periosteum of a bone or perichondrium of a cartilage
indirect attachment
muscles connective tisue wrappings extend beyond the muscle either as a ropelike tendon of a sheetlike aponeurosis
much more common because of durability and small size
sarcolemma
the plasma membrane of a muscle fiber, usually under the endomysium. below this is mutiple oval nuclei
sarcoplasm
the cytoplasm of a muscle cell contains large amounts of glycosomes
glycosomes
granules of stored glycogen that provide glucose during periods of muscle cell activity
myoglobin
a red pigment that stores oxygen
myofibril
rodlike contractile elements that occupy most of the muscle cell volume. they appear banded and have sarcomeres end to end. bundles of myofilament
sarcomere
the smallest contractile unit composed of myofilaments made of contractile proteins, region between the z disks made up of the a band and two half I bands at each end.
Thin filament
contain actin molecule
Thick filament
contain bundled myosin molecules
striations
a repeating series of dark and light bands are evident along the length of each myofibril
cross bridges
this forms when linking of the thin and thick filaments together occurs
actin
is a protein in which has a kidney shape and is used to bear the active sites in which myosin heads attach during contraction, polypeptide subunits they are in thin filament
tropomyosin
rod shaped protein that wraps around the thin filament to help stiffen and stabilize it (actin core)
troponin
globular three polpeptide complex one binds to tropomyosin another binds to actin and the last one binds calcium ions
titin
helps the muscle to spring back into shape after being stretched extends from the z disk to the thick filament and forms the core of the thick filament
muscle tone
relaxed muscles that are slightly contracted to keep the muscles firm and healthy and ready to respond to stimulation. helps maintain posture and stabilize joints
Aerobic endurance
length of time a muscle can continue to contract using aerobic pathways
anaerobic threshold
the point in time when muscle metabolism converts to anaerobic glycolysis
prime mover
muscle that has a major responsibility for producing a specific function
antagonist
muscles that oppose or revers a particular movement
synergist
help prime movers by adding a little extra force and reducing undesireable movements
fixators
synergists immobilize a boe or a muscles origin so that the prime mover has a stable base on which to act