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276 Cards in this Set
- Front
- Back
Muscle comprises _____ % of total body weight
|
35-45%
|
|
muscle is fromed of _____cells specialized for contraction possessing _______ containing ______ & _______
|
differentiated cells, contractile filaments containing actin and myosin
|
|
shape of muscle cells
|
elongated
|
|
are muscle cells polar
|
yes, ordered polarity w/ contraction along major axis
|
|
muscle possesses an ____ membrane which propagates ____& initiates ________
|
excitable, impulse, contraction
|
|
muscle is derived from _______ so has close assoc. w/ __________
|
mesoderm, CT
|
|
can muscle regenerate
|
to varying degrees
|
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3 types of muscle
|
skeletal, cardiac, smooth
|
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which muscles are striated
|
skeletal and cardiac
|
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which musches are voluntary
|
only skeletal
|
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which muscles are regenerative
|
skeletal is regenerative, smooth is moderately regenerative, cardiac is not
|
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type of contraction of skeletal muscle
|
strong, quick, discontinuous, voluntary
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type of cardiac muscle contraction
|
strong, quick, continuous, involuntary
|
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type of smooth musch contraction
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weak, slow, involuntary
|
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Skeletal muscle is not merely a tissue, it is an _______ containing ___, ____,&_____
|
organ, CT, blood vessels and nerves
|
|
skeletal muscle cells AKA
|
fibers
|
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skeletal muscle fibers are ______ packed, _____ organized, and exhibit ______ metabolic activity
|
densely, highly, high
|
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why do skeletal muscle have high metabolic activity
|
lots of mitochondria w/ enriched blood and nerve supply
|
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shape of skeletal muscle
|
cylindrical and elongated
|
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are skeletal muscle multinucleate
|
yes
|
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Skeletal muscle fibers from a morphological and funcational ________
|
syncytium
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Sk. mus., fibers have diameters of ___-____ and lengths from less than ____ to more than ______
|
diameter=10-100 micrometers
length=<1mm->30cm |
|
Skeletal muscle fibers types, (often all types are present in given muscle)
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red (slow twitch), white (fast twitch), & intermediate
|
|
Fiber types (red, white & int,) vary in content of ____, relative enrichment of _______ and various metabolic ___ as well was capacity for ____
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myoglobin, mitochondria, enzymes, rate of contraction
|
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what is myoglobin
|
carries O2 similar to hemoglobin
|
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what does epimysium cover
|
entire muscle
|
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what is epimysium made of and what is it often called
|
dense CT layer, rich in collagen, elastic and reticular fibers, called fascia
|
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what does perimysium divide muscle into
|
smaller fxnal units=fasicles
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endomysium divides fascicles into______
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fibers
|
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endomysium is rich in _____&_______ and provides pathways for ___&___ to supply muscle fibers
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collagen & reticular fibers, capillaries and nerves
|
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what is a skeletal muscle fiber formed by
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fusion of myoblasts (10-100micrometers in diameter)
|
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are all nuclei in skeletal muscle fibers myoblasts
|
no- satellite cells
|
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what are skeletal mm satelite cells
|
myoblastic stem cells
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where can skeletal mm satellite cells be found
|
under endomysium (1-2% of visible nuclei) adjacent to sarcolemma
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sketal mm satelite cells exhibit ____proliferative capactiy reflecting ___ ability of skeletal m.
|
high, regenerative
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what are the 2 types of fibers in skeletal m.
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extrafusal & intrafusal
|
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what are extrafusal and intrafusal muscle involved in
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extrafusal- contraction, intrafusal-reg. of contraction
|
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what innervates extrafusal skeletal m.
|
alpha motoneurons
|
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what does intrafusal muscle include
|
nuclear bag and chain fibers
|
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what is the prinicpal cytoplasmic component of the muscle fiber
|
myofibrils
|
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are myofibrils branched
|
no they are rods
|
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how far do myofibrils extend
|
full length of fiber
|
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what are myofibrils composed of
|
sarcomeres (fxnal units of skeletal and cardiac contractile apparati)
|
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what are sarcomeres limited by
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Z-line on each end
|
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what are myofibrils composed of
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2 myofilaments: actin and myosin
|
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what is the principal contractile protein of thin myofilaments
|
actin
|
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what does actin consist of
|
pair of helically entwined polymers (F-actin) of the globular (G-actin)
|
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Actin is assoc w/ the globuler _______ and the filamentous ______
|
troponin, tropomyosin
|
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toponin and tropomyosin conver _____ dependency on the ______ interaction
|
Ca++ ACTIN-MYOSIN INTERACTION
|
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What makes up troponin complex
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TnC, TnI, TnT
|
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What does TnC bind
|
Calcium
|
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what does TnI bind
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actin
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What does TnT bind
|
tropomyosin
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What color are Type I fibers
|
red
|
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what color are type II fibers
|
white
|
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what fibers have more glycogen
|
type II
|
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what fibers are slow oxidative and fatigure resistant
|
type I
|
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Myosin is held in register by crosslinkages of the protein ______ &______at the _______
|
myomesin & C=Protein at M-Line
|
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the "head" portion of myosin confers ______ activity and possesses _____
|
ATPase, actin binding site
|
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how are myosin arranged
|
polarized, antiparallel, with head and tail
|
|
A bands= "___ band" is ____ with ____ but stain darkly with most stains
|
dark band, anisotropic with polarized light
|
|
what does the A band contain
|
6 thin myofilaments surround each thick myofilament, the filaments overlap and interdigitate
|
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I bands= ______ w/ polarized light, appear ____ stain w/ most stains
|
isotropic, lightly
|
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what do I bands contain
|
only thin filaments
|
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H bands=have _____ central regions w/in _____
|
light, A bands
|
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what do H bands consist of
|
thick filaments only
|
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Where are M lines
|
center of H bands
|
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how do M lines appear
|
narrow and dark
|
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how are M line formed
|
from cross-connections of adjacent thick filaments by myomesin and C Protein
|
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Z-disks (lines) are dense regions bisecting each____
|
I band
|
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Z lines contain _______ which binds to _______ and anchorms them to the _____ with the assistance of ______
|
a-actinin, thin filaments, Z line, nebulin
|
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What large elastic cytoskeletal protein is assoc w/ Z line
|
titin
|
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where do titin span? what does it form? what does it contribute to?
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spans Z line to M line, foms elastic lattice, contributes to passive elasticity of sarcomere
|
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what surrounds sarcomere at Z line attaching it to the sarcolemma
|
desmin
|
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what stabilizes a-actinin /actin interaction @ Z-line
|
nebulin
|
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During contraction, thick and thin filaments do not _______ but _________
|
not shorten but overlap more
|
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_____ slide past _____ resulting in greater penetration into _____ which themselves remain a constant length
|
thin filaments slide past thickfilaments, A band
|
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_____ and ______ decrease in length as _____ are drawn closer together
|
I bands and H bands, Z disks
|
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cell membrane of muscle fiber AKA
|
sarcolemma
|
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sarcolemma is invested with an external ______________
|
basal lamina
|
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a single muscle fiber may have ____#___ of nuclei
|
thousands
|
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where are the nuclei of a muscle fiber located
|
in the periphery of the fiber beneath the sarcolemma
|
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cytoplasm of muscle fiber =
|
sarcoplasm
|
|
sarcoplasm hsa many ______
|
mitchondria
|
|
special form of sER of muscle fiber
|
sarcoplasmic reticulum
|
|
principle role of sarcoplasmic reticulum
|
sequester Ca++ during contraction
|
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sarcoplasmic reticulum is rich in _______ which binds to Ca++
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calsequestrin
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a depolarization signal is transferred from the sarcolemma to the interior of the fiber via ________
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T-tubules
|
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In response to depolarization the sarcoplasmic reticulum releases _____ sequestered in the_______ into the cytoplasm
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Ca++ , terminal cisternae
|
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The release of Ca++ enables the interaction of ____ and ____ resulting in shorteing of the ______ and muscle contraction
|
actin & myosin, sarcomere,
|
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Sarcolemma depolarization is linked to muscle at a structure called the _______
|
triad
|
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what are the membranous units of the triad
|
1 T-tubule + 2 terminal cisternae
|
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the transverse tubule is a tubular invagination of the _____
|
sarcolemma
|
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the T-tubule penetrates into the ________, perpendicular w/ ______
|
sarcoplasm, myofibrils
|
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the t-tubule is alighned w/ the _______
|
A-I band jxns
|
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the terminal cisternae is part of the _______
|
sarcoplasmic reticulum
|
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what is the attachment step of contraction
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not active step, In the absence of ATP (but w/ Ca++) the conformation of the myosin head allows for tight interaction w/ actin "rigor configuration"
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During step 2 of the contraction cycle "release" what happens
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ATP binds the S1 fragment of myosin head resulting in dissociation of myosin head from actin
|
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what causes step 3 of contraction "bending"
|
ATP hydrolyzed to ADP + Pi, both remaining w/ myosin head. Head pivots and aligns w/ adjacent actin monomer
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what causes step 4 of contraction : "force generation"
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"power stroke" Ca++ dep. phase. bound Pi and ADP release from myosin head and cross-bridge forms between myosin and actin
|
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During step 5 of contraction "reattachment" the ____ undergoes conformational change, resulting in tight interaction of _______ & ______
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myosin head, actin & myosin
|
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During reattachment interaction of actin and myosing causes what
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pulling of actin filament toward center of sarcomere, shortening it
|
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what happens to contraction cycle when ATP is not available
|
bind of actin and myosin is stabilized (Step I attachment)and rigor mortis occurs after death
|
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_____ the source of energy for skeletal muscle contraction is formed from ______ by several processes
|
ATP, ADP
|
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How is ATP formed in white (fast) fibers
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ATP is generated by anaerobic glycolysis resulting in buildup of lactic acid
|
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How is ATP formed in red (slow) fibers
|
ATP is generated by oxidated phosphorylation
|
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How else is ATP formed
|
ATP is formed from transfer of phosphate in creatine phosphate to ADP in rxn catalyzed by phosphocreatine kinase
|
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Skeletal muscle is __ dep, and occurs in what 3 phases
|
Ca++,
depolarization and Ca++ release, activation of actin by calcium, relaxation |
|
depolarization and calcium release triggers binding of ____ & ______
|
actin & myosin
|
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pathway of depolarization in skeletal muscle
|
sarcolemma @ motor-ene plate (AKA myoneural jxn)->T tubules->myofibrils
|
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Where is Ca++ released into the cytosol in skeltal muscle
|
at A-I jxns via voltage reg. channels in SR terminal cisternae
|
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In the resting state, the ____-bind sites on actin are covered by _______
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myosin, tropomyosin
|
|
_______ is also bound to actin hindering ______ binding
|
Troponin I, actin/myosin
|
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In active state, binding of Ca++ by _______ resulting in conformation change interrupting the _______ interaction
|
troponin C, TnI/actin
|
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what happens when TnI and actin separate
|
tropomyosin shifts unmasking myosin binding sites
|
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when does relaxation occur in skeletal muscle
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when Ca++ conc in cytoplasm is reduced and TnC loses its bound Ca++, tropomyosin returns to resting state
|
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what is relaxation dep. upon
|
ca++ pump in sarcoplasmic reticulum, translocating Ca++ from cytosol to inner surface of SR membrane where they are sequesterred by calsequestrin
|
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what does the motor unit consist of
|
a neuron and the skeletal muscle fibers it innervates
|
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all muscle fibers obey the _______ law
|
all or none
|
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muscle fibers of the same motor unit contract in ______
|
unison
|
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The force generated by a muscle is dependent upon what
|
the # of motor units undergoing contraction at the same time
|
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In Fine coordination muscles (i.e. ocular, digital) one nerve can only innervate ____ muscle fibers
|
one to 3
|
|
in muscle used for coarse movement, (i.e. postural muscles) 1 nerve can innervate how many muscle fibers
|
hundreds
|
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each muscle fiber has how many motor end plates
|
1
|
|
motor end plate AKA
|
myoneural jxn, neuromuscular jxn
|
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3 components of motor end plate
|
axon terminal, synaptic cleft, muscle fiber
|
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at the motor end plate the nerve axon ____- and ________ with the sarcolemma to form _____
|
expands and invaginates, jxnal folds
|
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On the presynaptic jxnal fold there are many _____- containing ______
|
synaptic vesicls containing Ach
|
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Depolarization of the nerves causes _______ of the contents of the ______, spilling Ach into the synaptic cleft
|
exocytosis, synaptic vesicles
|
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Ach in synaptic cleft activates ____ on ______ resulting in ______ of the muscle fiber membrane and contraction
|
receptors, sarcolemma, depolarization
|
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____ innervation of ____ muscle is provided in part by muscle spindles
|
sensory, skeletal
|
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muscle spindles are _____ organs (________)
|
sensory, stretch receptors
|
|
shape of muscle spindles
|
elongated and fusiform
|
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what is muscle spindle bound by
|
CT capsule enclosing a fluid-filled space containing 8-10 modified muscle fibers referred to as intrafusal fibers
|
|
what fibers is the muscle spindle surrounded by
|
normal skeletal fibers (extrafusal)
|
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the muscle spindle is anchored via the ______ to the _____ &_______ of adjacent fibers
|
capsule, perimysium & endomysium
|
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Innervation of muscle spindles consists of ____ &______ nerve fibers
|
sensory (afferent) and motor (effered)
|
|
2 types of nerve endings of afferent nerves
|
annulospiral endings, flower spray endings
|
|
what type of nerve fibers have annulospiral endings
|
type 1a
|
|
Annulospiral endings wind around the center of _____ & ____ fibers
|
nuclear bag and nuclear chain
|
|
annulospiral endings respond to _________
|
rate of stretching
|
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flower spray endings are on what type of fibers
|
type IIa
|
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where do flower spray endings terminated
|
on either side of annulospiral endings
|
|
what do flower spray endings respond to
|
duration of stretching
|
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what do efferent nerves consist of
|
gamma 2 and gamma3 efferent axons
|
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what happens when efferent nerves are stimulated by over-contractions of the muscle
|
depolarize intrafusal fibers to counteract muscle stretching
|
|
tapping patellar tendon stretches the quadriceps femoris muscle and its _____
|
muscle spindles
|
|
The ____ nerves innervating the intrafusal fibers sned impulses to the spinal cord signaling a ________ of intrafusal fibers
|
afferent, stretch
|
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In the spinal cord the ______ synapse with _____ nerves that travel in both ______ and _____ motoneurons back to both extrafusal and intrafusal fibers causing contraction
|
afferent, efferent, alpha and gamma,
|
|
The "_____ loop" causes the ______ reflex and is a measure of _____ fxn
|
reflex, knee jerk, CNS
|
|
Cardiac muscle contracts _____, ____ &______
|
spontaneously, rhythmically, continuously
|
|
cartiac muscle is modulated by ______ &_______ nervous stimuli
|
endocrine and autonomic nervous
|
|
Cardiac muscle is located w/in the _____ of the heart and within proximal portions of the _____- &_____
|
myocardium, aorta & vena cava
|
|
Cardiac muscle is under _____ control
|
involuntary nervous
|
|
Are cardiac muscle fibers a synctial network
|
no, individual cells
|
|
do cardiac muscle of regenerative capacity
|
almot none, replace w/ CT scar
|
|
the sarcoplasm of heart muscle contains more ____, ___ and ____ than skeletal muscle
|
glycogen, lipid, mitochondria
|
|
How does heart muscle contract and relax
|
same steps as skeletal muscle
|
|
how many nuclei does cardiac muscle have and where
|
1 or 2 central
|
|
does cardiac muscle branch
|
yes
|
|
is cardiac muscle striated
|
yes
|
|
what are cardiac muscle cells lined by
|
external (basal) lamina
|
|
_____ and _______ are esp. enriched at poles of nucleus in region called _______ in cardiac muscle
|
mitochondira, glycogen granules, sarcoplasmic cone
|
|
purpose of cardiace muscle in whorled pattern
|
enables myocardium to wring out blood from chambers of heart
|
|
CT element are between cardiac muscle fibers (like endomysium) and support a rich ______ that supports ______ of tissue
|
rich capillary bed, high metabolic activity
|
|
cardiac muscle cells are joined by ______ which provided _____ & ______
|
intercalated discs, mechanical & electrical cellular coupling
|
|
what parts of intercalated discs have jxns specializations
|
transverse and lateral
|
|
3 jxns of transverse portion of intercalated discs
|
fascia adherents, maculae adherents (desmosomes), gap jxns
|
|
what jxn does the lateral portion of intercalated disc possess
|
gap jxn
|
|
fascia adherents is analogous to _______- of epithelia to which _______ attach
|
zonula adherens, actin filaments
|
|
purpose of fasciae adherents in intercalated discs
|
anchor site for sarcomeres nearest to the end of the cells
|
|
purpose of maculae adherents (________) in intercalated discs
|
desmosomes, bind cells to prevent separation during contraction
|
|
Gap jxns form the portion of the intercalated disc that lies in a place ____ to the ____ of the cell
|
parallel to the long axis
|
|
Purpose of gap jxns in intercalated discs
|
direct electrical communication between cells
|
|
which has larger T tubules, skeletal or cardiac muscle
|
cardiac
|
|
cardiac T tubules are lined w/ ________
|
external lamina
|
|
is the sarcoplasmic reticulum is cardiac muscle well developed
|
`no poorly developed
|
|
Each cardiac cell T tbuble is asso. w/ _#_terminal cisterns forming _____ instead of ____
|
1, dyads instead of triads
|
|
Dyads are located at the ____ in cardiac muscle rather than the A-I jxns in skeletal muscle
|
Z lines
|
|
cardiac muscle contains many ____, and ____ mitchondria than skeletal muscle
|
more, larger
|
|
Sarcoplasmic reticulum in heart contributes to ___
|
dyads
|
|
sarco. reticulum in cardiac mm leak _____ into the _____ at a slow and constant rate contibuting to the ______
|
ca++, sarcoplasm, automatic rhythm
|
|
where are mitochondria in cardiac mm
|
parallel to the I bands
|
|
where are atrial granules found
|
in atrial cardiac muscle cells (otherwise these cells are identical to other cardiac mm cells)
|
|
atrial granules contain the precursor _____ which is secreted in response to an increase in ______
|
atrial natriuretic peptide, blood pressure
|
|
Atrial natriuretic peptide causes excretion of _____ in uring reducing the workload of the heart by modulation of _____, _____, and _____
|
salt,
BP, blood volume, cardiac output |
|
how does nervous innervation affect cardiac mm
|
speed up or slow down intrinsic beat
|
|
cardiac mm are innervated by branches of _____ & ____ nervous systems, which terminate where?
|
sympathetic and parasympathetic, terminating near (not on) muscle cells
|
|
where is the initiating stimulus for contraction in cardiac mm
|
sinoatrial node
|
|
the SA node delivers the stimulus to modified cardiac m. fibers in the _____ of the ventricles and eventually to the _____
|
endocardium, Purkinje fibers
|
|
Purkinje fibers communication w/ many ordinary cardiac m cells via _____
|
gap jxns
|
|
where are Purkinje fibers located
|
atrioventricular bundle of His
|
|
Are Purkinje fibers bigger or smaller than reg cardiac m cells
|
bigger
|
|
Purkinje fibers have large # of ____
|
gap jxns
|
|
Purkinje fibers have a lower content of ____ and a higher content of _____
|
lower myofibrils, higher glycogen
|
|
smooth muscle is mostly assoc w/ _____ organs
|
hollow
|
|
smooth muscle occurs in ____ or _____ at ____ angles
|
sheets or layers at rt. angles
|
|
what control smooth m
|
autnomic nervous system
|
|
how does contraction rate of smooth m. compare to skeletal m.
|
smooth m. contracts 10x more slowly
|
|
smooth muscle can maintain contraction of _____ periods of time
|
extended
|
|
smooth m can contract up to ____% of length
|
75
|
|
does smooth muscle have T tubule system
|
no
|
|
is smooth m striated
|
no
|
|
smooth muscles ranges in length from ____ (small blood vessels) to ______ (pregnant uterus)
|
20 micrometers to 500 micrometers
|
|
2 types of smooth m based on fxn
|
unitary/visceral smooth m, multi-unit smooth m.
|
|
where is unitary visceral smooth m,
|
in the walls of hollow viscera (intestinal walls, bronchi, ureters, uterus, fallopian tubes)
|
|
Unitary/visceral Smooth m is richly innervated by the ______ serving mainly to __________
|
autonomic nervous system, increase or decrease levels of spontaneous contraction
|
|
how else are unitary/visceral smooth m contractions initiated
|
nerve action, stretch, irritation
|
|
unitary/visceral smooth muscle have many ____ between cells serving to________
|
gap jxns, propagate wave of depolarization
|
|
where does multi-unit smooth m. occur
|
iris of eye, walls of some large arteries, ductus deferens
|
|
______ activity _____ controls multi-unit smooth muscle fibers
|
autonomic, precisely
|
|
contractions of multi-unit smooth m. is typically initiated by _______
|
neural discharge
|
|
multi-unit smooth m. cells are not _____ or not well-_____ electrically
|
coupled, coupled
|
|
electrical properties of multi-unit smooth m. cells are influenced by both ______-&________
|
hormones & autonomic neurotransmitters (epinephrine and norepinephrine)
|
|
shape of smooth muscle
|
spindle shaped
|
|
location of nucleus in smooth m
|
central
|
|
color of cytoplams in smooth m
|
eosinophilic
|
|
smooth muscles occur in bundles of _____ size
|
varying
|
|
bundles of smooth m. can be ____ oriented (as in arteries)
|
helically
|
|
most of sarcoplasm of smooth m. is occupied by ________ which insert into ______
|
actin filaments, dense plaques
|
|
where are cytoplasmic organelles confined to in smooth m.
|
conical regions at ends of central nucleus
|
|
Smooth m. nucleus have a _____ shape and is deeply _____ in longitudinal sectiong through smooth m. fibers
|
cork-screw, indented
|
|
is actin and myosin organized into myofibrils in smooth muscle
|
no
|
|
contractile myofilaments actin and myosin are attached to _____&____ densities in smooth muscle
|
peripheral plaques and cytoplasmic densities
|
|
how are actin and myosin aligned in smooth m
|
obliquely to the longitudinal axis of SMCs
|
|
Intermediate filaments of SMCs are:
|
desmin (non-vascular SMCs) and vimentin (vascular SMCs)
|
|
intermediate filaments are anchored to _____ in SMCs
|
cytoplasmic densities
|
|
do SMCs have troponin
|
no replaced by caldesmin and calponin
|
|
dense plaques (cytoplasmic densities) of SMCs are comparable to _______
|
Z discs
|
|
dense plaques (cytoplasmic densities are enriched w/ _____ and serve as primary sites of _______
|
alpha-actinin, filament attachment
|
|
Sarcolemmal vesicles AKA
|
caveolae
|
|
Sarolemmal vesciles (caveolae) are present where in SMCs
|
along periphery
|
|
fxn of caveolae in SMCs
|
uptake and release of Ca++
|
|
Why does SMC contraction occur more slowly and last longer than skeletal muscle contraction?
|
slower rate of ATP hydrolysis
|
|
As in skeltal muscle, SMC contraction results from ____ & _______ interaction
|
actin and myosin
|
|
Are SMC thick and thin filaments arranged into sarcomeres?
|
no, this only happens in striated muscle
|
|
____, ____ and _____ insert into the dense plaques in SMCs
|
actin, myosin & intermediate filaments
|
|
when the SMC contracts, ____ pulls on the dense plaques, causing a ruffling of the cell and a ______ shaped nucleus
|
actin, corkscrew-shaped
|
|
SMC contraction cycle is stimulated by _________
|
transient increase in cytosolic ca++
|
|
Step I of SMC contraction: _____ binds to _____ altering its conformation
|
Ca++ , calmodulin
|
|
Step 2 of SMC contraction: ca++/calmodulin complex activates _______which leads to _______ of light-chains of myosin
|
myosin light-chain kinase, phosphorolates
|
|
Step 3 of SMC contraction: phophorolated globular head then interacts w/ ____, stimulating _______ resulting in contraction
|
actin, myosin ATPase
|
|
As long as the _______ remains phosphorolated, the contraction cycle will continues
|
light-chains of myosin
|
|
Step 5 of SMC contraction: _____ of myosin prevents ____ binding resulting in relaxation
|
dephosphorylation, actin
|
|
2 types of contractile non-muscle cells
|
myoepithelial cells, myofibroblasts
|
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where are myoepithelial cells located
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between the epithelium and basal lamina of certain types of glands and in ductal portions of glands
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purpose of myoepithelial contraction
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assist in expression of glandular material
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myoepithelial cells are similar in ____ to SMCs but possess a _______ morphology w/ multiple ______
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shape, basket-like, processes
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where doe myoepithelial cells arise from
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ectoderm
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where do SMCs arise from
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mesoderm
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contractile apparatus and cycle of myoepithelial cells is comparable to that of ______
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SMCs
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in lactating mammary glands, ____ contractions is initiated by _____
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myoepithelial, oxytocin
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in lacrimal glands ____ contaction is initiated by _____
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myoepithelia, acetylcholine
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myofibroblasts resemble ____ but possess high amounts of ____ and ____ facilitating contraction
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fibroblasts, actin & myosin
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what may myofibroblasts contribute to
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wound healing contracting to decrease size of defect
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Duchenne muscular dystrophy (DMD) is a ____-linked (most common in ________), ____ genetic defect
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sex-linked, young men, recessive
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DMD results in _____ synthesis of ______
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decreased, sarcolemmal protein dystrophin
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pathological signature of DMD
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replacement of degenerating skeletal muscle fibers w/ fatty and fibrous CT
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DMD may also affect ____ muscle
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cardiac
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DMD result in death in most ppl by age ___
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20
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Myostatin mutation causes _____
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skeletal muscle hypertrophy
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what is the myostatin mutation commonly observed in
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mice and cattle- 1 human case
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Myostatin mutation does what to myostatin
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loss of function of gene
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What is myostatin
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GDF-8, growth factor regulating size of muscles beginning in utero
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Pathological results of myostatin mutation
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hypertrophy of skeletal muscle, also expressed in heart (cardiomyopathy)
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Myasthenia gravis is a ____ disease where ______ blocks ____ of the ______
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autoimmune, antibodies block Ach receptors of motor-end plates
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Myasthenia gravis pathological characteristics
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gradual weakenings of skeletal muscles esp. those most used( extraocular, tongue, facial expression, etc.)
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Clinical symptoms of myasthenia gravis
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high circulating titer of antibodies to Ach receptros
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why might myasthenia gravis be fatal
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respiratory compromis resulting in pulmonary infection
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What is botulism caused by
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food poisoning (Clostridium botulinum)
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What does Clostridium botulinum do
|
inhibit Ach release at motor-end plates
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Clinical signs of botulism
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muscle paralysis, vomiting, visual disorder and death if untreated
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what does the golgi tendon organ monitor
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tension developed in muscle
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what does golgi tendon organ consist of
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afferent fibers
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what does golgi tendon organ prevent
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damage during excessive forcer generation
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GTO stimulation results in _____ of muscle via _______ inhibition of ______
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reflex relaxation, interneuronal, alpha-motoneurons
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