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what are the three types of muscle?
Skeletal, Cardiac, Smooth
What are some attributes of skeletal muscle?
-striated
-voluntary
-move bones of the skeleton
What are some characteristics of Cardiac muscle?
-Found only in the heart
-Striated
-Involuntary-autorythmic
What are some characteristics of smooth muscle?
-located in walls of hollow internal structures.
-non-striated
-involuntary, some mild autorythmicity.
what are the functions of muscle tissue?
-producing body movements
-stabilize body positions
-store and move substances
-generate heat(thermogenesis)
what is a muscle?
an entire organ
what is a muscle fiber?
a single muscle cell
what is a fascicle?
a bundle of muscle fibers(cells)
what is a myofibril?
an organelle of a muscle fiber (muscle cell)
what is a filament?
a fibrous protein molecule within a myofibril
what give a cut of meat the characteristic grain?
The fascicles
what is the CT surrounding the entire muscle?
Epimysium
what is the CT that surrounds a muscle fiber?
endomysium
what is the CT that surrounds a fascicle?
Perimysium
What is a broad flat tendon?
an aponeurosis
Endomysium, perimysium and epimysium blend together and tie into?
a tendon
what does a somatic neuron supply?
a group of muscle fibers
what is a motor unit?
a group of muscle fiber with a somatic neuron.
how many neurons per muscle fiber?
one
What is a neuromuscular junction?
site where the neuron contacts the muscle fiber
what fuse to form one skeletal muscle fiber during embryonic development?
a number of myoblasts
What are characteristics of muscle fibers due to their development?
-multinucleate
-unable to undergo mitosis
What is a sarcolemma?
the plasma membrane of a muscle fiber. it encloses the sarcoplasm and myofibrils.
where is the nuclei of a muscle cell?
just inside the sarcolemma
what is the cytoplasm of a muscle fiber called?
sarcoplasm
what composes a myofibril?
-bundles of filiments that are the contractile elements of the cell.
-contractile organelle
what are T-tubules?
-transverse tubules that invaginate from the sarcolemma and extend toward the inside of cell.
-open to the outside of the fiber, filled with interstitial fluid(ECF)
-important in propagation of action potentials
what is the sarcoplamic reticulum?
the Smooth ER of a muscle fiber.
-it stores Ca ions, and releases them when stimulated.
What is the dilated region that flank the T-tubules?
Terminal cisterns
what do you call 2 terminal cisterns flanking one t-tubule?
a triad
what are two types of filiments that make up myofibrils?
-Thin: actin(contratile), troponin & tropomyosin (both regulatory)
-Thick: Myosin (contractile)
what is the ratio of thin to thick filaments?
2 thin- 1 thick
Filaments inside a myofibril are arranged in compartments called?
sarcomeres
what is the basic functional unit of a myofibril?
a sarcomere
thick and thin filaments overlap differently dependant on?
the contraction state of the muscle
The pattern of overlap gives rise to a number of zones and bands.  What are they?
-A band
-I band
-Z line
-H zone
- M line
the center of an I band, where adjacent sarcomere butt up?
Z discs
Darker zone, which comprises the length of the thick filaments and a carying overlap of thin filaments
A Band
only thin filaments
I Band
Center of an A band; only thick filaments
H zone
midline of a sarcomere
M line
What do the heads (crossbridges) of myosin molecules do?
-Bind and hydrolyze ATP, also binds products of ATP hydrolysis.
-changes shape (moves toward or away from M line)
-bind reversibly to actin
what covers the myosin binding sites at rest?
regulatory proteins troponin and tropomyosin
each individual actin molecule has what?
a myosin binding site
what allows contraction to begin?
movement of the troponin-tropomyosin complex
what triggers the movement of the troponin-topomyosin complex for myosin to bind to actin?
Ca binding to troponin
increase in the diameter of muscle cells.
hypertrophy
what are characteristic of hypertrophy?
-organelles increase in number
-capable of more forceful contractions because they contain more myofibril.
-only occurs in striated muscle.
incrase in size of tissues and organs due to an increase in the number of cells
Hyperplasia (smooth muscle of the airway, vascular system, and urogenital tract)
what is myoglobin?
red colored, oxygen binding molecule found only in muscle that is similar to Hgb in composition and function.
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