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73 Cards in this Set
- Front
- Back
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types of muscle tissue
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skeletal and cardiac, and smooth
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skeletal muscle
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attaches to bone, skin or fasia, striated with light and dark bands visible with scope, voluntary control of contraction and relaxation
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cardiac muscle
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striated in appearance, involuntary control, autorythmic branched, cells connected by inercalated discs with gap juctions
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smooth muscle
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attached to hair follicles in skin
in walls of hollow organs nonstriated in appearance twists to contract to shorten involuntary |
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functions of muscle tissue
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producing body movement
stabilizing body positions regulating organ volumes movement of substances within the body producing heat |
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properties of muscle tissue
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exitability
conductivity contractability extensibiltity elasticity |
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exicitiability
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respond to chemicals released from nerve cells
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conductivity
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ability to propagate electrical signals over membrane
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contractibility
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ability to shorten and generate force
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extensibility
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ability to be strectched without damaging the tisse
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elasticity
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ability to return to original shape after being strecthed
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superficial facsia
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seperates muscle from skin, is composed of areolar connective tissue and adipose tissue
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deep fascia
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is dense and irregular connective tissue that lines the body wall and limbs and holds muscles
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epimysium
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surround the whole muscle
connective |
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perimsium
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surround bundle of 10-100 muscle cells
connective |
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endomysium
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seperates individual muscle cells
connective |
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what extends from the muscle belly to form tendons
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epimysium, perimysium, endomysium
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muscle fibers
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long cylindrical and multinucleated
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sarcolemma
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muscle cell membrane
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what is sarcoplasm filled with
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tiny thread called myofibrils and myoglobin
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T tubules (transverse)
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of the sacrolemma into the center of the cell, filled with extracellular fluid, carry muscle action potentials down into cell
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where are mitochondria
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lie in rows throughout the cell, near the muscle proteins that use ATP
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sarcoplasmic reticulum (SR)
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system of tubular sacs similar to smooth ER in nonmuscle cells, stores Ca+2, in a relaxed muscle, release of Ca+2 triggers muscle contraction
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atrophy
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wasting away of muscle
caused by disuse the transition can not be reversed |
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hypertropy
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increase in the diameter of muscle fibers
resulting from very forceful repetive motion |
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sacromere
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thick and thin filaments overlap each other in a pattern that create striations
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proteins of muscle tissue
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myofibrils are built of 3 kinds of proteins
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contractile proteins
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myosin and actin
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myosin
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thick filaments are composed myosin
each molecule resembles 2 golf clubs twisted together crossed bridges extend toward the thin filaments |
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actin
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thin filaments are made of actin troponin, and tropomyosin
thin filaments are held together by Z lines is covered by tropomysin in relaxed muscle |
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regulatory proteins
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turn contraction on and off
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tropomysin
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covers myosin binding sites on actin in relaxed muscles
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titan
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achors thick filaments to the M line and the Z disc. the portin of the molecule between the Z and the end of the thick filaments can stretch
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myomesin
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the M line connects to titan and adjacent thick filament
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nebulin
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and inelastic protein helps align the thin filaments
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dystrophin
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links thin filaments to sacrolemma and transmits the tension generated to the tendon
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nerve impulse
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reaches an axon terminal and synaptic vesicle release acetylcholine
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ACh
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diffuses to receptors on the sacrolemma and Na+ channels open and Na+ rushes into the cell
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muscle action potential
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spreads over sarcolemma and down into the transverse tubules
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SR
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releases Ca+2 into the sacroplasm
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Ca+2
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binds to troponin and causes troponin-tropomyosin complex to move and reveal myosin binding sites on actin
the contraction cycle begins |
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4 stages of the contraction cycle
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ATP hydrolysis
attachment of myosin and actin to form crossbridges power stroke attachment of myosin from actin |
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reminder about ATP and myosin
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myosin heads are activated by ATP
activated heads attach to actin and pull (powerstroke) ADP is released thin filaments slide past the thick filaments ATP binds to myosin head & detaches |
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rigor mortis
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is a state of muscular rigidity that begins 3-4 hr after death and lasts about 24 hrs
after death Ca+2 ions leak out of the SR and allow myosin heads to bind to actin, since ATP synthesis has ceased |
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neuromuscular junction
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end of axon nears the surface of a muscle fiber at its motor plate region (remain seperated by synaptic cleft or gap
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botulinum
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botox blocks the release of neurotransmitter at the NMJ so muscle contraction can not occur
bacteria found in impoperly canned food death occurs from paralysis of the diaphram |
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curare
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plant poison from poison arrows
used to relax muscle duing surery |
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neostigmine
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blocks removal of ACh from receptors so streghtens weak muscle contractions of myashenia gravis
also an antidote for curare after surgery is finsihed |
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muscle metabolism
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muscle uses ATP at a great rate when active
sarcoplamic ATP only lasts for few seconds |
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sources of ATP within muscles
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creatine phospate
aerobic cellular respiration anaerobic cellular respiration |
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creatine phospate
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energy rich molecule that is found only in muscle fibers
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aerobic celluar respiration
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ATP for any activity lasing over 30 seconds
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anaroebic cellular respiration
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ATP produced from glucose breakdown into pyruvic acid during glycosis if not present
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muscle fatigue
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inability to contract after prolonged activity
central fatigue is feeling of tiredness and desire to stop depletion of creatine phospate decline of Ca+2 |
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oxygen consumption after exercise
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muscle has 2 sources of oxygen
diffuses in from blood released from myoglobin inside muscle fibers aerobic system requires O2 to produce needed to prolong activity, lactic acid is converted to pyruvic acid |
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motor unit
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one somatic motor nueron and all the skeletal muscle cells it stimulates
muscle fibers normally scattered throughout the belly of muscle one nerves cell supplies on average 150 muscle cells that all contract in unison |
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motor unit recruitment
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motor units in a whole muscle fire asynchornosty
some fibers are active, others are relaxed delays muscle fatigue so contraction can be sustained produces smooth muscular contration precise movements |
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muscle tone
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involuntary contraction of a small # of motor units
keeps muscles firm even though relaxed essential for maintaining posture important in maintaining BP tone of smooth muscle in walls |
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isotonic contraction
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a load is moved
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isometric contraction
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no movement occurs
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red fibers
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more myoglobin and oxygen-storing reddish pigment more capillaries and mitochondria
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white fibers
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less myoglobin and less capillaries give fibers their pale color
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slow oxidative
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slow twitch red in color lots of mitochondria, myoglobin,and blood vessels
prolonged sustained contractions for maintaining posture |
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fast oxidative glycoltic
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fast twitch A
red in color split ATP at very fast rate used for walking and sprinting |
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fast glycolytic
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fast twitch B
white in color anaerobic movement for short duration, used for weight lifting |
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regeneration of muscle
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skeletal muscle fibers cannot divide after 1st year
growth is elargement of existing cells repair cardiac muscle cannot regenerate of divide, smooth muscle regeneration is possible |
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myasthenia gravis
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progressive auto immune disorder that blocks the ACh receptors at the NMJ
the more receptors are damaged the weaker the muscle |
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muscular dystrophies
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inherited muscle destroying disease
sarcolemma tears during muscle contraction mutated gene is on the x chromosome so problem is with males almost exclusivley |
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spasm
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involuntary contraction of single muscle
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cramp
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a painful spasm
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tic
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involuntary twitching of muscles normally under voluntary control
eyelid or facial muscle |
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tremor
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rhymtic involuntary contraction of opposing muscle groups
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fasciculation
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involuntary brief twitch of a motor unit visible under the skin
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