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69 Cards in this Set
- Front
- Back
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Muscle properties
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Carries out movement -bones and tissue (contracts)
Consumption of ATP into work - movement of a load (chemical energy into mechanical energy) Structure dictates how muscles function |
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Movement due to muscle
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posture
respiration communication heart pressure generation intestinal movement and mixing |
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Thermoregulation
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40% of body tissues is muscle, generates a ton of heat (energy not used for motion is used for heat)
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Contractions (shortening, causing muscle tension) -
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fibers shorten, generate force and pull on bones, pressure
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Excitability
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respond to stimlus, CNS(skeletal muscle), hormones, physical (smooth muscles from hormones and physical)
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Extensibility
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stretch past original length
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Elasticity
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Recoil after stretch (strenthened rubber band)
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Skeletal (basic)
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Voluntary (you decide to make it contract)
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Smooth (basic)
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Widely distributed, involuntary
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Cardiac (basic)
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Only in heart, involuntary
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Skeletal Histology
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Red(mioglobin - containing heem(has iron) coloring it red and carrying oxygen, striated
muscle fibers (striations)-run from one end of the muscle to the other Connective tissue Blood supply Nerves |
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Myo-
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prefix refering to muscle
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In series
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has a repeating pattern all across (the fibers)
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Muscle Fibers
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made up of myocytes (fusion of myocytes)
Set at birth (no new fibers) Lengthens during growth Diameter changes with use (like appositional growth in bone) |
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Individual fibers
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10-80 microns in diameter
up to 25 cm in length repeating internal pattern = sarcomere |
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Sarcolemma
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Cell membrane - wraps around smaller internal fibers
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Myofibrils
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smaller fibers within a fiber
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Transverse tubule
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wraps itself around fibrils (carries stimulations) cuts through fibrils
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Sarcoplasmic reticulus, longitudinal tubules of...
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endoplasmic reticulum, but in bone and is a calcium depository
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Z band
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darkests area, boarders of Sarcomere
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External lamina
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next to sarcolemma (next to myocyte)
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Endomysium
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next layer
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Perimysium
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fasciculi - covering several fibers
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Epimysium
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covers sever fasciculi - fascia
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Continuous with connective tissue to bone
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Periosteum
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hold muscle intact
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acts as a unit
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Motor neurons
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neurons that excite skeletal muscle
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neuromuscular junction
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junction they make with muscle fibers
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a motor neurons
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cell bodies - ventral horn of the spinal cord (axon comes out of spinal cord to muscle) - innervate (make a synaps with) single muscle fibers NMJ(ask Shea)
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Motor unit
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a motor neuron and innervated muscle fibers
contract synchronously (at the same time) size of motor unit ~ with muscle function |
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Ascetile Choline Ach
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the neurotransmitter at the neuromuscular junction NMJ
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action potential duration
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5 millisec to send signal (mylinated for speed)
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muscle tension
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20 millisec to contract
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Muscle fiber(site of contraction)
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sarcolemma...
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Mysin
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thick filiment
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actin
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thin filiment
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Z line attached with actin
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I band
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Titin
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the largest protien in the human body, attaching myosin (H band)
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Sarcomere (description)
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...
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Sarcomere (function)
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T tubules - invagination of the sarcolemma, in contact with extracellular space
terminal cisternae - region of SR clostest to t tubule, calcium release |
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Myosin (detail)
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480000 mw
6 different... ATPase - can consume atp |
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Actin
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42000mw
.... |
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Nebulin
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protein, reference point, length of thin filiment, organization and elasticity
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tropomyosin
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..in thin filiment, covers 7 actin molecules
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Troponin
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.. in thin filiment
T- binds tropomyosin I-blocks mysin and actin binding C-binds calcium |
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Sliding filament model
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Crossibridges between thick and thin
move filaments past one another energy requireing Myosin head(ratching) and actin filament moves 10nm for each ATP releases and re-attaches |
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Ratcheting
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Happens because of thermodynamics - each time it moves it moves toward an energetically stable state
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Cyclic steps
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look at slide 30
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ATP
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required to reset the myosin head
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rigor mortis
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stopping of the cycle
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Process
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see slide 31
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Contracture and rigor mortis
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insufficientcy of ATP, cannot relax, strnuous activity
death... |
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Excitation-contraction coupling
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action potential- Ach release, binds to NMJ
open channels, na enters, graded potential-action potential of myocyte membrane depolarize transverse tubules - deep into muscle As release from SR from terminal systerne |
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Calcium increase (what it does)
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Ap opens Ca channel - ryanodine receptor (RYR) channel
spans between t tubule.... |
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Process
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Ap- conformational change in DHPR(changes shape) as the electrical depolarization passes through T tubule
Altered DHPR interacts with RYR and opens Ca channel SERCA - sarcoplasmic reticulu... |
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Why calcium
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ca binds to troponin, moves, allow crossbridges by changing troponin shape
calcium gets tropomyocin out of the way to allow crossbridge formation Ach removed by acetyl... |
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More crossbridges formed, due to more calcium)
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more tension
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tropomyocin (analogy)
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breaks on a bike
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Muscle twitch
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single action potential traveling down a motor neuron
a single motor unit lag or latent period; followed by contraction, then relaxation |
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Single motor unit
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sub-threshold - no AP - no twitch
threshold - AP - one twitch Supra-threshold - AP - one twitch |
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Whole muscle
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frequency of action potentials ~ recruitment(activating motor units)
Tetanus- recruitment of all motor units Treppe- contractive force is increased after maximal stimulus (athletes) (dumps calcium into SR, so you have some when you start the actual race/game) |
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Slow twitch fibers
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40 - 90 msec to develop maximal tension
lower frequency of simulus induces tetany (in legs) |
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fast twitch fibers
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7.5 msec
higher frequency of stimulus induce tetany (in hands) |
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Concentric contraction
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muscle shortens, force is less than maximal, normal actions
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Eccentric contraction
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activation when lengthening, dropping a heavy load, greatest tension
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Isotonic contraction
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activation, load, shortening, normal action
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isometric contraction
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activation, no shortening
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passive stretch
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lengthened during passive stretch
to maintain flexibility around joints |
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muscle tone
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contrant contraction at low level
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