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49 Cards in this Set
- Front
- Back
myosin stats
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made of 200 - 500 myosin molecules
2 entwines polypeptides(look like golf clubs) |
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polypeptides
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tails face the center and heads face the outside
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central area of myosin
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bare area with no heads, only tails
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Actin
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thin filament
two intertwines strans fibrous actin globular actin with an active site |
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tropomyocin
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long orange protein that stops mucles from contracting
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Troponin
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one small calcium binding molecule for each tropomyocin.
large amounts of calcium changes troponin shape, and pulls out topomyocin, causing a contraction. |
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contractile proteins
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myosin and actin(doers)
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Regulatory proteins
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tropomyocin and troponin
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steps of T & T
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switch starts and stops muscle.
contraction activated by release of calcium into the sarcoplasm and its binding to troponin troponin moves tropomyocin off the actin active site. |
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Dark Band
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A band (thick filament region)
Myosin |
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Light Band
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I Band (thin filament region)
Actin gets shorter with contraction |
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sarcomere
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from 1 Z-disk to the next is one sarcomere.
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H zone
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Light strand between dark bands.
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Symatic motor neurons
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make ACh- acetocoline
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ATP Pump
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makes a cell electrically excitable, by pumping Na, and K in and out of the cell.
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Resting Membrane Potential
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Inside the cell is -80/-90mV
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Relax
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Potasium is running inside the cell
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Contract
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Sodium going outside the cell
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Electrical stimulus begins
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when the pump runs
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Muscle contraction and relaxation
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1. excitation- nerve action potentials lead to action potentials in nerve fibers
2. Excitation contraction coupling- action potentials on the sarcolema activate myofilaments 3.Contraction- shorteing of muscle fiber 4. Relaxation- return to resting length |
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1. Excitation
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Nerve signal opens voltage gated calcium stimulates exocytosis of synaptic vesicles containing ACh, then ACh releases into the Synaptic cleft.
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Wave Peaks
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when the wave peaks it will begative on the on the outside and positive on the inside.
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membrane voltage
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will determine whether the gate on the synaptic knob will open or close.
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End Plate Petential
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Binding ACh to Receptor Proteins will open Na and K channels resulting in a jump in RMP from -90 to + 75mV
Don't move anywhere. Triggers action Plate. |
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Action Potential
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Voltage change in EPP opens nearby voltage gated channels, this is like a wave
It does move.voltage gauged by sodium and potasium |
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2. Excitation Contraction Coupling
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action potential spreading over sarcolema enters t-tubules voltage gated channels open in t-tubules causing calcium gates to open in SR
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T-Tubules carry what?
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action potentials through the sarcolema.
this electrical activity releases calcium from the sarcolema. |
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Calcium from SR
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Binds to troponin, the toponin, tropomyocin complex changes shape and exposes active sites on actin.
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3. Contraction
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Myosin ATP in myosin head hydrolyzed on ATP molecule, activating the head and "cocking" it in on extended position
myosin head binds to actin active site forming cross bridge. |
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Power Stroke
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myosin head releases ADP and phosphate as it flexes pulling the thin filament past the thick.
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Sliding Filament Theory
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thick and thin filaments dont become shorter, they just slide part eachother.
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4.Relaxation
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Nerve stimulus ceases ACh- sterase removes ACH from receptors, stimulation of the muscle cell ceases.
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In relations Active Transport
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Pumps calcium back into the SR, through active calcium pumps.
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relaxation and ATp
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ATP is needed for relaxation as well as contraction.
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Rigamortis
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calcium leaks from SR, causing the muscles to contract.
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Exocytosis
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is triggered by calcium
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Calcium Channels
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open during voltage change and calcium then difuses in SR and bonds with troponin
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AChe
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is found in Synaptic CLeft, eats away ACH when not absorbed.
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Length Tension Relationship
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Amount of tension generated depends on length of muscle, or sarcomere before it was stimulated.
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Overly COntracted
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Weak!
Thick filament to close to Z disk and cant slide. |
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too Stretched
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Weak!
little overlap of thin and thick does not allow for ery many cross bridges to form. |
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Optimum Resting Length
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Produces greatest Force.
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Threshold
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voltage producing on action potential.
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Twitch
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a single breif stimulus at that voltage produces a quick cycle of contraction and relaxation, lasting less than 1/10 of a second.
single twitch is very weak. |
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Latent Period
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the time between the stimulus starts and when the contraction begins.
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Threshold Stimuli
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Produces twitches, but twitches of individual muscle fibers remain unchanged despite increased voltage.
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variability in contraction
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due to Ca2 concentration, previus stretch of the muscle, temperture, ph, and hydration.
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Recruitment and stimulus intensity
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stimulating a whole nerve with higher voltage produces stronger contractions
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Multiple Motor Unit Summation
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More motor units are being recruited
also known as spatial summation |