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What are the types of muscle tissues
Skeletal, cardiac, and smooth
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What does the skeletal muscle do
attaches to bones and skin, its striated, voluntary, and powerful
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What is the cardiac muscle
Its only in the heart, striated and involuntary
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What is the smooth muscle
In the walls of hollow organs, stomach, urinary bladder, blood vessels, and airways, not striated, involuntary
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What are the muscle functions
The movement of bones of fluids, mainting posture and body positions, stabilizing joints, and heat generation
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What happens in the skeletal muscle
each muscle is served one artery, one nerve, and one or more veins
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The Epimysium does what
surrounds the entire muscle, covered by what makes up tendons
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What does Perimysium do
surrounds fascicles
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What surrounds each muscle fiber
Endomysium
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Muscles attach
Directly and indirectly
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What happens Directly
epimysium of muscle is fused to the periosteum of bone or perichondrium of cartilage
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What happens Indirectly
connective tissue wrappings extend beyond the muscle as a ropelike tendon or sheetlike aponeurosis
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What are myofibrils
densely packed, rodlike elements, 80% of cell volume
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Exhibit striations are what
perfectly aligned repeating series of dark A bands and light I bands
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What is the smallest contractile unit muscle fiber, region of a myofibril between two successive Z discs, thick & thin myofilaments made of contractile proteins
Sarcomere
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what are the features of sarcomere
thick filaments, thin filaments, and z discs
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What do thick filaments do
run the entire length of an A band
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What do thin filaments do
run the length of the I band and partway into the A band
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What do Z discs do
Connect myofibrils to one another
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What is contraction
The generation of force, does not cause shortening of the fiber, shortening occurs tension generated by cross bridges thin filaments exceeds forces opposing shortening
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What are the requirements for skeletal muscle contaction
activation and excitation
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What is activation
neural stimulation at a neuromuscular junction
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What is excitation
Contraction coupling, generation and propagation of an action potential along the sarcolemma, final trigger a brief rise in intracellular Ca2+ levels
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What are the cross bridge cyle
cross bridge formation, working stroke, cross bridge detachment, cocking of the myosin head
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high energy myosin head attaches to thin filaments
cross bridge formation
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myosin head pivots and pulls thin filament toward M line
Working stroke
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ATP attaches to myosin head and cross bridge detaches
cross bridge detachment
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Energy from hydolysis of ATP cooks the myosin head into the high-energy state
cocking of the muscle head
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What is an isometric contraction
no shortening, muscle tension increases but does not exceed the load
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What is a Isotonic contraction
muscle shortens because muscle tension exceeds the load
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What is a motor unit
a motor neuron and all muscle fibers it supplies
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What is a large motor unit
In large weight bearing muscles(thighs, hip)
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What is a small motor unit
units in muscles that control fine movements
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