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65 Cards in this Set
- Front
- Back
striations results from
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an overlapping of internal contractile proteins
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endomysium is connective tissue around
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muscle cells(muscle fiber)
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perimysium is connective tissue around
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muscle fascicles(bulk of muscle fibers)
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epimysium is connective tissue around
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the entire muscle
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myofibrils
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long protein bundles that occupy the main portion of the sarcoplasm
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myofibrils consisting of what proteins? 2
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glycogen
myoglobin |
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myoglobin
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red pigment; stores oxygen needed for muscle activity
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myoblasts
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stem cells that fuse to make each myofibril
myo (muscle fiber) blasts (stem cells) |
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satellite cells
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unspecialized myoblast cells remaining btw muscle fiber and endomysium
can regenerate a damaged muscle fiber |
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calcium reservoir in a myofibril?
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sarcoplasmic reticulum
Calcium activates muscle contraction |
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thick filaments made up of?
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hundreds of myosin molecules
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Thin filament composed of two ______
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fiborus (F) actin beads entwined
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G actin
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a string of subunits that has an active site that can bind to the head of a myosin
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When a muscle fiber is ______, each tropomyosin blocks the active sites of G actins and prevents myosin from binding to them.
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relaxed
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What stabilizes the thick filament, centers between the thin filaments, prevents over-stretching and contributes to elastic recoil?
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elastic filaments!
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elastic filaments aka 2
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titin
connectin |
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contractile proteins 2
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myosin
actin -they do the work |
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regulatory proteins 2
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tropomyosin
troponin -when can a fiber contract or not |
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True or false
Neither the thick or thin filaments change length during shortening. |
True
only the amount of overlap changes |
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Skeletal muscle never contracts unless
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stimulated by a nerve
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denervation atrophy
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shrinkage of paralyzed muscle when connection not restored.
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somatic motor NEURONS
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nerve cells in the brainstem and spinal cord that serve skeletal muscles
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somatic motor FIBERS
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the AXONS that lead to the skeletal muscle
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motor unit
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one NERVE FIBER and all the MUSCLE FIBERS innervated by it
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synaptic knob
contains? |
swollen end of nerve fiber
-synaptic vesicles filled with acetycholine (ACh) |
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schwann cell
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envelops and isolates all of the NMJ from the surrounding tissue fluid
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How is ACh released into the synaptic cleft?
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by exocytosis
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Basal lamina that catches the ACh by its receptors contains:
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acetylcholinesterse (AChE)
that breaks down ACh after contraction causing RELAXATION |
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ACh think
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contraction
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AChE think
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relaxation
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________ stimulates exocytosis of ACh from synaptic knob.
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Calcium
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Rigor mortis
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hardening of muscles and body beginning 3-4 hours after death and peaks at 12 hours
-muscle relaxation requires ATP |
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all-or-none law
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contracting to its maximum or none at all
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recruitment or multiple motor unit (MMU) summation
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process of bringing more motor units into play
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isometric muscle contraction
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muscle develops tension but does not shorten
ex: holding a dumbell without moving it causes internal cellular tension causing it to stay the same length or longer |
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isotonic muscle contraction
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muscles changed in length with no change in tension
ex. muscle begins to shorten and move the load |
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2 enzyme systems control phosphate transfers in generating ATP in immediate energy:
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myokinase
creatinine kinase |
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ATP and CP=
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phosphagen system: short burst of energy
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As the phosphagenic system gets exhausted, it shifts to ___________.
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anaerobic fermentation
30-40 seconds of max activity |
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anaerobic fermentation think:
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glycolysis
can generate 2 ATP for every glucose molecule consumed |
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glycolysis converts ______ to ______.
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glucose to lactic acid
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2 ways beating fatigue
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oral creatinine
carbohydrate loading |
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what part of the body are Slow oxidative, slow twitch, red or type I fibers?
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calf and postural muscles of the back
-adapted for aerobic respiration and fatigue resistance |
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Fast glycotic (FG), fast twitch, white or type II fibers found where?
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extrinsic eye muscles, gastrocnemius, biceps brachii
-fibers well adapted for quick response but not for fatigue resistance |
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muscular strength depends on:
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muscle size
fascicle arrangement size of motor units: the larger the stronger multiple motor unit summation: recruitment temporal summation length-tension relationship fatigue |
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____________ allow each myocyte to directly stimulate its neighbors (cardiocyte)
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Gap junctions
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_________ is capable of mitosis and hyperplasia
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smooth muscle
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In smooth muscle, Z discs are replaced by ________.
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dense bodies
-well ordered array of protein masses in cytoplasm |
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multiunit smooth muscles occurs where? how?
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largest arteries, pulmonary air passages, pilo erector muscle and iris
- each myocyte receives its own nerve supply |
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single unit smooth muscle where? how?
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blood vessels, digestive, respiratory, urinary and repro tracts
-a nerve fiber passes through the tissue without synapsing with any specific myocyte= coupled by GAP junctions -cells contract as a single unit |
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visceral muscle, think:
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single unit smooth muscle
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Layers of the mucosa: 3
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epithelium
lamina propria muscularis mucosa |
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layers of the muscularis externa:
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circular layer
longitudinal layer |
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pacemaker cells
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set off a wave of contractions in the entire layer of muscle
stomach/intestines |
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varicosities
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beadlike swellings each containing synaptic vesicles
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In smooth muscles, calcium enters and binds to _______ on thick filaments. Not troponin like skeletal and cardiac muscles
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calmodulin
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Ca2+ > ?
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calmodulin
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calmodulin > ?
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activtes mysoin light-chain kinase
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mysoin light-chain kinase >
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adds phosphate to regulatory protein on myosin head
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then >
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myosin ATPase, hydrolizing ATP enables myosin similar power and recover as skeletal muscle
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latch-bridge mechanism
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resistant to fatigue
-enables it to remain attached to actin for a prolonged time without consuming more ATP |
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stress-relaxation response?
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helps hollow organ gradually fill (UB)
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plasticity
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the ability to adjust its tension to the degree of stretch
-UB can stretch without getting flabby |
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strabismus
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inability to fixate on the same point with both eyes
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Tx of myasthenia gravis
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cholinesterase inhibitors
immunosuppressive agents thymectomy plasmapheresis |