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172 Cards in this Set
- Front
- Back
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EPIMYSIUM
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dense connective tissue continuous with tendon - surrounds the muscle
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PEIMYSIUM
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CT tissue surrounding fascicles
contains smaller blood vessels and nerve branches |
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FASCICLES
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muscle fibers/cells (myofibers) - CONTRACTILE CELLS
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Myofiber
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muscle cell - contractile
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each myofiber is surrounded by _____
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basal lamina
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muscle satellite cells
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stem cells
found in basal lamina |
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ENDOMYSIUM
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surrounds myofibers and satellite cells
includes reticular fibers, ECM and basal lamina contains capillaries |
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Proprioceptors
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Golgi tendon organs
at junction between muscle fibers and tendons |
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Muscle spindles are found
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within the perimysium
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What synthesizes the basal lamina around myofibers?
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MYOBLASTS
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Musculotendinous junction
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terminal expansion of muscle fibers
increases surface area of contact btw muscle fiber end and CT forming the tnendon transmits force from muscle to tendon |
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PENNATION ANGLE
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angle of muscle fiber insertion into musculotendinous juction TO the line of force generated
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MOTOR UNIT
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motor neuron plus its innervated fibers
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Mosaic patterns are the result of ____
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fibers of different motor units intermixed within a fascicle
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alpha motor neuron
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large motor neuron of CNS
innervates extrafusal muscle fibers |
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extrafusal myofibers
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major force generators
innervated by alpha motor neuron |
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Where are AChRs on a muscle fiber membrane?
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At the NMJ
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gamma motor neurons innervate _____
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intrafusal fibers (afferent)
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muscle spindles
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fusiform CT capsule encloses intrafusal muscle fibers and sensory endings
located in perimysium responsible for stretch reflex |
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Golgi tendon organs (GTOs)
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mechanoreceptors that respond to tension
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Why do skeletal myofibers have multiple nuclei?
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to support the extensive protein synthesis required throughout the life of the cell
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sarcoplasmic reticulum surrounds each _____
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myofibril
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MYOFIBRIL
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cylindrical bundle of contractile proteins
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A band --> light/dark?
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DARK
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I band --> light/dark?
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LIGHT
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In skeletal muscle, what do centrally located nuclei indicate?
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fiber injury/repair
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sarcolemmal invaginations deep into interior of the myofiber
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T-tubules
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interior of T tubules are confluent with what fluid?
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EXTRACELLULAR FLUID
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dilations at the end of the SR
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cisterna
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sarcolemma associated TRIAD
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cisternae of 2 adjacent collars close to one T tubule
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sarcomeres are placed end to end, so that ...
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shortening of all sarcomeres means the myofibril shortens
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3 protein components of THIN filaments
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ACTIN
tropomysin troponin |
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3 subunites of troponin
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tropomyosin binding subunit
Ca++ binding subunit inhibitory subunit |
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what protein complex regulates actin and myosin binding?
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troponin-tropomyosin complex
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In a molecule of MYOSIN,
one head binds to ___ the other binds to ____ |
ATP
ACTIN |
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2 myosins join...
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tail - to - tail
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A band represents region of
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THICK FILAMENTS
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I band represents region of
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THIN FILAMENTS
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Z disc/line function
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anchors thin filaments
includes actin binding proteins |
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M disc/line
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anchors THICK filaments in center region
(where there are only myosin tails) |
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Titin
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largest polypeptide known
extends from Z line to M line regulates assumbly of myosin into thick filaments |
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2 proteins that link sarcomeres to sarcolemma, ECM and each other
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Desmin
Dystrophin |
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Function of DESMIN
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intermediate filament
links Z discks of adjacent myofibrils so that they remain aligned |
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Genetic disorders of desmin result in
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progressive myopathy
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Function of DYSTROPHIN
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anchors actin of thin filaments to the INTEGRIN family of glycoproteins in the plasmalemma, which bind proteins in the basal lamina
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Genetic disorder in which dystrophin is absent
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Duchenne muscular dystrophy
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Proteins involved in regulation of muscle growth
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IGF-1 (from damaged myofibers)
Mysotatin growth hormone insulin testosterone |
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Hormones that increase muscle growth via sarcomere number
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GH
insulin testosterone |
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CROSS BRIDGE
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actin-myosin link
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Cross bridge cycle
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actin mysoin link (attachment)
ATP cleavage movement |
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Cross bridge cycle continues as long as...
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ATP and Ca2+ supplies last
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Rigor
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attachment of myosin and actin - tightly bound
very brief in living tissue |
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Release (in cross bridge cycle)
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ATP binds to myosin
conformational changes produced in myosin head myosin now has lower affinity for binding actin and releases actin |
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Hydrolysis/Bending (in cross bridge cycle)
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ATP hydrolyzed to produce energy to rotate myosin head towards Z line
actin and myosin still not bound |
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Power stroke (in cross bridge cycle)
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Requires Ca2+
myosin head returns to original orientation, pulling the tightly bound actin with it |
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Force generating step of cross bridge cycle
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Power stroke
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The concentration of what regulates the initiation and duration rest of cross bridge cycling?
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Ca++
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At rest, the concentration Ca++ in cytosol is ____
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LOW
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In the cross bridge cycle, absence of Ca++...
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troponin interferes with optimal actin-myosin binding, and there is no ATP hydrolysis
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DHSR
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voltage gated receptor on T-tubule membrane
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ryanodine receptor (RyR)
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Ca++ channel protein in sarcolemma
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EMG
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electromyologram
- records electrical activity in muscles |
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Fibrillation
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spontaneous contraction of a muscle fiber
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When do fibrillations occur
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Denervated muscle fibers initally depoloarize, esp. at the end plate, and generate fibrillations
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Fasciculation
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spontaneous firing of a motor unit
driven by activity in motor axon visible under the skin and may occur normally |
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First step in muscle activation blocked by
LIDOCAINE |
neuron action potential
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First step in muscle activation blocked by
Myasthenia gravis (decrease in AChR) |
End plate potential
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First step in muscle activation blocked by
BOTULINUM TOXIN (blocks ACh release) |
End plate potential
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First step in muscle activation reduced by
DYSTROPHIN DEFECT |
Power stroke (muscle fiber shortening or force)
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First step in muscle activation reduced by
Blocking DHSR |
Sarcomere Ca++ reuptake
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Isometric contractions
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muscle cannot shorten, and in response develops force or tension
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Concentric contractions
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muscle develops force and shortens
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Eccentric contractions
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muscle develops force but also lengthens
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Vmax of muscle
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maximum shortening velocity for a muscle in isolation, in the absence of any load
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Fmax of musce
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maximum force generated by muscle
same as peak isometric force (ergo, velocity of shortening at Fmax = 0) |
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Every cycle of myosin-actin binding and release requires ___ ATP
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1 ATP per cycle
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Type I myosin
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slowest cycling rate
uses LEAST ATP/time |
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Type IIa and IIx
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faster cycling rates
use MORE ATP/time |
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high energy phosphate store in muscle
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phosphocreatine
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CK catalyzes what 2-way reaction in muscle
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ADP + PCr <----> ATP + Cr
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PCr acts as what during the process of contraction?
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a buffer
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two pathways that replenish creatine pool
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Glycolysis
Oxidative Phosphorylation |
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Type I (SO) fibers depend more on _____ metabolism
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AEROBIC
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Type IIx (FG) fibers depend more on ______
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GLYCOLYSIS
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Type IIa (FOG) fibers depend on _____ metabolism
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both AEROBIC and GLYCOLYTIC
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Characterisitcs of Type I (SO) myofibers
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myoglobin:oxygen binding (increases rate of O2 uptake)
--> RED muscles more mitochondria smaller diameter more surrounding capillaries |
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Type II fibers
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larger diamters
fewer mitochondria and surrounding capillaries less myoglobin more extensive SR = rapid Ca2+ release/resuptake |
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The nervous system acts ONLY on ___
NOT on ____ and ONLY by VARYING ____ |
The nervous system acts only on MOTOR UNITS, not individual muscle fibers, and only by VARYING the EXCITATION
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tetanus
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sustained contraction, rather than individual twitches
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Spatial summation
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increasing contraction force by recruiting MORE MOTOR UNITS
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Order in which fiber types are recruited in spatial summation and WHY
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Type I (less force, less easily fatigued)
then Type II (more force, more easily fatigued) allows nervous system to produce precise level of force |
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How are the nuclei located in CARDIAC muscle?
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CENTRALLY
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Which type of muscle has intercalated discs?
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CARDIAC
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What type of muscle exhibits BRANCHING?
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CARDIAC
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4 types of cardiac muscle cells
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Atrial working muscle cells
Ventricular working cells Nodal cells Purkinje fibers |
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Both atrial and ventricle working cells provide ______
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CONTRACTILE FORCE
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Diameter of ventricular working cells
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10-25 microns
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Lenth of ventricular working cell myofibers
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50 - 100 microns
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Size of atrial working cells relative to ventricular working cells?
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SMALLER AND SHORTER
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Size of Purkinje cells relative to ventricular cells?
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LARGER AND LONGER
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Which type of cardiac mucle cell exhibits the least obvious striations?
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Purkinje fibers
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Which type of cardiac muscle cell exhibits the greatest glycogen stores?
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Purkinje fibers
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Organelle taking up the most room in a cardiac muscle cell
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MYOFIBRIL
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Organelle with the second-to-greatest volume in a cardiac muscle cell
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mitochondria
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Myofibrils of cardiac muscle are virtually identical to the myofibrils of what type of muscle?
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skeletal
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Where are T tubules located in CARDIAC MUSCLE?
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at Z lines
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Diads are formed by SR and T tubules in what type of muscle
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CARDIAC
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3 specialized structures found in INTERCALATED DISCS between cardiac muscle cells
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gap juntions
maculae adherens (desmosomes) fascia adherens |
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Major difference between ATRIAL and VENTRICAL working myofibers
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ATRIAL working cells produce SECRETORY GRANULES that releas ANP with STRETCH
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ANP
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atrial natriuretic peptide
released in response to STRETCH |
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In LM, striations + secretory granules suggest...
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ATRIAL MUSCLE
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In cardiac muscle, adjustment of force of contraction is the result of what 2 things?
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lenth-active tension relationship
changes in contractility DIFFERENT FROM SKELETAL MM |
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Does spatial and temporal summation occur in cardiac muscle? Why or why not?
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NO
ALL working cells contract each time the heart beats electrophysiology does NOT ALLOW temporal summation |
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Define contractility
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ability to develop contractile force at a given muscle length
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As resting cardiac muscle length is INCREASED, force of contraction ___
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INCREASES
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Two characteristics of muscle/environment during ASCENDING part of force vs. length curve
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INCREAESD cytosolic Ca2+
INCREASED sensitvity of myofibrils to Ca2+ |
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Myofibril characteristic during DESCENDING part of force vs. length curve
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Decreased overlap of myosin heads and actin active sites
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What NT increases contractility?
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NE
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Signaling mechanism initiated by NE
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NE --> betaAR --> Gs --> AC --> cAMP --> PKA --> phosphorylation of Ca2+ regulatory proteins
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Phosphorylation of DSHRs -->
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increased entrance of activatory Ca2+ --> increased release Ca2+ from SR --> increased cytosolic Ca2+ --> Ca2+ binds Troponin C --> ALLOWS MYOSIN-ACTIN interactions
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2 Ca2+ regulatory proteins phosphorylated by PKA
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DSHRs
phospholamban |
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The only ANS nerve type that releases an NT other than ACh (and what it releases)
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POSTganglionic SYMPathetic nerons release NE in MOST TISSUES
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What cell type releases NE and epinephrine?
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Chromaffin cells
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Where are chromaffin cells found?
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Adrenal medulla
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What nerve type innervates chromaffin cells?
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PREganglionic SYMPathetic neurons
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What kind of AChRs do POSTganglionic nerve bodies express?
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nicotinic (Nnerve)
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What do M1, M3 and M5 receptors signal through?
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Gq (PLC)
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What do M2 and M4 receptors signal through?
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Gi (cAMP inhibition)
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alpha1 receptors are found on
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vascular smooth muscle
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alpha 2 receptors are found on
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postganglionic SNS endings
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beta1 receptors are found on
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cardiac cells
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beta2 receptors are found on
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vascular smooth muscle
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beta2 receptors are found on
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fat cells
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Nerves of the non-adrenergic, non-cholinergic (NANC) nervous system release
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Substance P
Vasoactive intestinal peptide |
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Neurotransmitters released by the ANS
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ACh
NE NO Neuropeptide Y Vasoactive intestinal peptide ATP |
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Dual innervation means
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effector tiddues are innervated by both sympathetic and parasympathetic neurons
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Dual RECIPROCAL innervation means
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sympathetic and parasympathetic neurons may have opposing actions
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Three characteristics of AXON REFLEX in ANS
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NO synapse involved
SEnsor fibers (axons) give off branch (collateral) that go to blood vessels Glu, Substance P, and sometimes calcitonin gene releated peptide cause vasodilation |
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ANS reflexes coordinated in AUTONOMIC GANGLIA are especially common in the ____
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GI tract
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Three levels of organization of the ANS
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no synapse
autonomic ganglion synapse spinal cord synapse |
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Higher centres can facilitate or inhibit what type of ANS reflex?
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those coordinated in the spinal cord, e.g.: micturition, defecation, ejaculation, erection
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5 examples of ANS reflexes controlled in the medulla oblongata
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swallowing
vomiting BP regulation respiration pupillary reflexes |
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Most important ANS structure for afferent input in the medulla
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nucleus tractus solitarius (NTS)
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3 inputs to NTS
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stretch receptors and chemoreceptors from every ofgan of the thorax and abdomen
hypothalamus cerebral cortex |
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outputs from the NTS go to:
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CNS regions including hypothalamus
preganglionic sympathetic and parasympathetic nerves |
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5 ANS activities coordinated in the hypothalamus
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temperature regulation
cardiovascular functions feeding, fighting, fleeing and fucking circadian rhythms |
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Signal pathway to increase HR
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sympathetic postganglionic fibers --> NE --> beta adrenergic receptors --> cardiac pacemaker cells --> increased HR
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Signal pathway to decrease HR
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parasympathetic postganglionic fibers --> ACh --> muscarinic cholinergic receptors --> cardiac pacemaker cells --> decreased HR
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Signal pathway to stimulate aqueous salivary secretion
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parasympathetic postganglionic fibers --> ACh --> muscarinic cholinergic receptors --> salivary gland cells --> aqueous secretion
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Signal pathway to stimulate protein salivary secretion
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sympathetic postganglionic fibers --> NE --> beta adrenergic receptors --> salivary gland cells --> protein secretion
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Signal pathway causing constrition of arterioles
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sympathetic postganglionic fibers --> NE --> alpha-AR --> contriction of arterioles
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Signal pathway to dilate arterioles
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adrenal medulla --> epinephrine --> beta-AR --> dilation of arterioles
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ACh causes endothelial cells to release ____
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nitric oxide (NO)
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ACh-stimulated pathway to relaxation of vascular smooth muscle
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ACh --> M3 --> NO synthase converts Arg to NO --> NO activates guanylate cyclase --> GC coverts GTP to cGMP --> relaxation of vascular smooth muscle
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Some effectors that are not innervated by _____ respond to artificially elevated ACh
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parasympathetic nerves
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What NT mediates parasympathetic effects in external genitalia
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NO
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Sildenafil inhibits what enzyme/reaction in corpus cavernosum smooth muscle?
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PDE, which converts cGMP to GMP
resulting accumulation of cGMP sustains dilation |
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Are cholinergic effects always parasympathatic effects?
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NO
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Muscarinic cholinergic receptor antagonist
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atropine
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Nicotinic cholinergic receptor antagonist
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trimetaphan
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Alpha adrenergic receptor antagonist
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phentolamine
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Beta adrenergic receptor antagonist
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propranolol
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Stimulators of the MAPK pathway
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growth factors
mitogens inflammatory response stress |
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Two examples of GTPases used in MAPK pathway
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Ras
Rac |
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GTP hydrolysis stimulates what three branches of the MAPK pathway?
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Raf --> MEK1/2 --> ERK --> c-fos --> proliferation
MEKK3/TAK --. MKK --> p38MAPK 00 --> c-jun --> dx, inflamm, PCD MEKK/MLKs --. MKK --. SAP/JNK --> c-jun --> dx, inflamm, PCD |
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What do MAPKs do?
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Phosphorylate transcription factors
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3 MAPKs
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ERK
p38MAPK JNK |
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Proteins with SH2 domains do what?
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Serve as couplers between TKs and downstream signaling
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2 major signaling pathways coupled to TKs
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MAPK pathway
PI3 Kinase pathway |
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2 proteins with SH2 domains
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MAPK
PI3 Kinase |
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Oncogenes
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genes of tumor causing viruses that are responsible for the transformation of cells
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protooncogenes
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genes in normal cells that are the same or similar to oncogenes
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