Muscle cells respond to neural, stretch, or other signals by changing their _______. -
sarcolemma electrical potential (voltage)
The electrical potential change is coupled to intracellular changes that result in ______.
- force generation (contraction)
Contractility - active shortening of muscle cell and generation of tension (force)
Extensibility - passive stretching of muscle cells
Elasticity - return of muscle cells to original resting length after being stretched
Which muscle tissue(s) has cells w/ obvious stripes called striations - skeletal, cardiac
Which muscle tissue is voluntary and which is involuntary? - voluntary-
skeletal......involuntary-cardiac,smooth
What muscle tissue contracts rapidly but tires easily? - skeletal
Cardiac muscle contracts at a rate set by the heart's ________. - pacemaker
Which muscle tissue is primarily found in the walls of hollow visceral organs? - smooth
Which muscle tissue forces food and other substances through internal body cavities? -
smooth
What are the three connective tissue sheaths? - endomysium, perimysium, epimysium
What is a fine sheath of connective tissue composed of reticular fibers surrounding each
muscle fiber? - endomysium
What is fibrous connective tissue that surrounds groups of muscle fibers called
fascicles? - perimysium
,What is an overcoat of dense regular connective tissue that surrounds the entire
muscle? - epimysium
each muscle is served by ________. - one nerve(bundle of nerve fibers), an atery, and
one or more veins
when muscles contract... - the movable bone (insertion) moves toward the immovable
bone (origin)
How does a muscle attach to a bone directly? - epimysium of the muscle is fused to the
periosteum of a bone (less common)
How does a muscle attach to a bone indirectly? - connective tissue wrappings extend
beyond the muscle as a tendon or aponeurosis that attaches to a bone (more common)
What is a single muscle cell called? - a myocyte or muscle fiber
Myocyte size - 10 to 100 micrometers in diamter and many 10s of cm long
Each mature myocyte is created by fusion of multiple precursor cells called _________.
- myoblasts
Sarcoplasm has numerous ________ and an oxygen-binding protein called _________.
- glycosomes, myoglobin
Myocytes contain the usual organelles, as well as.... - myofibrils, sarcoplasmic
reticulum, T-tubules
Densly packed rodlike contractile elements are called ________. - myofibrils
What is the smallest contractile unit of a muscle called? - a sarcomere
What is the region of a myofibril b/w two succesive Z-discs? - a sarcomere
What is a sarcomere composed of? - thick and thin myofilaments made up of contractile
proteins
How long does a thick filament of a myofilament extend? A thin filament? - thick: the
entire length of an A-band
thin:across the I band and part way into the A band
What is a coin-shaped sheet of proteins (connectins) that anchors the thin filaments and
connects myofibrils? - Z-disc
, Where do elastic filaments stretch and what are they made of? - from Z-disc through the
thick filament to the M-line.
a huge protein called titin.
What are thick filaments composed of? - 200-500 myosin protein molecules
What protein has a rod-like tail and two golbular heads? - myosin
What is the primary contractice protein in thin filaments and what is it made out of? - F-
actin
each F-actin strand is a double helical polymer of individual globular subunits called G-
actin
Each G-actin subunit contains an active site to which _______ attaches to during
contraction. - a myosin head
What is a filamentous protein bound in the grooves of the F-actin helix that blocks the
myosin binding site inrelaxed muscle? - tropmyosin
What is troponin and what does it do? - a regulatory protein complex bound to F-actin
and tropomyosin, and binds calcium ions
Sarcolplasmic reticulum is a type of ________ that mostly runs ________ and
surrounds each ________. - elaborate, smooth ER
longitudinally
myofibril
_________ of SR form perpendicular cross channgels. - paired terminal cisternae
The sarcoplasmic reticulum functions to regulate intracellular _________ levels. -
calcium
Elongated tubes of sarcolemma called ________ penetrate into the cell's interior at
each A band-I band junction - T-tubules
T tubules associate with the paired terminal cisternae to form _________. - triad
junctions
T-tubules are part of the ________. - sarcolemma
The electrical impluses from T tubules signal for _________ from the adjacent terminal
cisternae into the sarcoplasm (cytoplasm) - Ca2+
The Ca2+ released by T-tubules binds to ____ - troponin
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