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105 Cards in this Set
- Front
- Back
Cell membranes
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1
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Integral proteins achored by what forces?
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hydrophobic interaxn
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Peripheral proteins are loosely attached to membrane by?
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electrostatic interaxn
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Another name for tight junctions?
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Zona occludens
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Diffusion equation?
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J = -PA(C1-C2)
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Relationship b/t oil/water coef and permeability
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Direct
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Relationship b/t radius and permeability
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Inverse
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Relationship b/t membrane thickness and permeability
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Inverse
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Tm means?
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The transport maximum; correlates to carrier saturation
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Osmolarity equation?
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Osmolarity = # particles x conc (M)
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Osmotic pressure equation (van't Hoff's law)?
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p = # x conc x RT
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If reflection coef is 1, means?
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Solute is impermeable
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If reflection coef is 0, means?
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Solute is permeable
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Potentials
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7
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Conductance of ion channel depends on?
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Probability that channel is open
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2 types of ion channels gates?
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Voltage gated, ligand gated
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Size of diffusion potential depends on?
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size of conc gradient
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Sign of diffusion potential depends on?
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If diffusing ion is + or -
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Equilibrium potential is achieved when?
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Diffusion potential balances tendency to diffuse
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Equilibrium potential equation (Nernst equation)?
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E = -2.3(RT/zF)log[Cin]/[Cex]
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What does -2.3(RT/F) equal?
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negative 60 millivolts
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Equi pot of Na?
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65
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Equi pot of Ca?
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120
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Equi pot of K?
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neg 85
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Equi pot of Cl?
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neg 85
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Resting membrane potential?
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neg 70 millivolts
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Depolarizations makes the membrane potential
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less negative
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Hyperpolarization makes the membrane potential
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more negative
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Inward current is the flow of what charge into cell?
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Positive charge
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Outward current is the flow of what charge out of cell?
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Positive charge
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3 characteristics of action potential are?
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stereotypical size and shape, propagating, all-or-none
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Resting membrane potential is the result of?
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High resting conductance to K
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Upstroke steps? 3
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Inward current -> depolarization -> rapid opening Na channel (inward current)
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Overshoot is?
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Brief portion of AP when membrane potential is positive
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TTX and lidocaine block?
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Voltage-sensitive Na channels
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Role of inactivation gates in repolarization
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Depolarization close them slowly -> return Na conductance down to 0
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Role of K channel in repolarization
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Depolarization slowly open K channel (outward current) -> incr to higher than at rest
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Undershoot is?
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Hyperpolarization; when K conductance is higher than at rest
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Absolute v. relative refractory period
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Absolute cannot elicit new AP; relative can but requires larger inward current
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Accomodation is?
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When cell membrane held at depolarized level so threshold passed w/o firing AP
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Why can accomodation occur?
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Depolarization closes inactivation gates of Na
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What dz state demonstrates accomodation?
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hyperkalemia
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Relationship b/t fiber size and conduction velocity?
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Direct
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NMJ
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12
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Inhibitory neurons fx on post-synaptic membrane
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Hyperpolarize
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Excitatory neurons fx on post-synaptic membrane
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Depolarize
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Role of choline acetyltransferase
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Acetyl coA -> Ach
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Steps in motor neuron transmission 5
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Depolarization -> open Ca channel -> Ca relase synaptic vesicles -> Ach diffusion to end plate nicotinic receptors -> EPP
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Nicotinic receptors are which gated channel?
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Ligand
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MEPP is?
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smallest possible EPP; produced by one synaptic vesicle
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Is EPP a form of AP?
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NO!!! It is a depolarization of specialized muscle end plate
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Role of acetylcholinesterase?
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Degrade Ach -> acetyl coA + choline
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Where does botox work?
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Block release of Ach from presynaptic terminal
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Where does neostigmine work?
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Inh AChE
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Where does curare work?
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Competes with Ach for motor end plate R
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What dz attacks Ach R, reducing the number available?
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Myasthenia gravis
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List excitatory NT: 5
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Ach, norepi, epi, dopa, glu, 5HT
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List inhibitory NT: 2
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GABA, gly
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How do EPSP work?
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Depolarize postsynaptic cell
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What causes EPSP?
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Opening Na, K channels
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How do IPSP work?
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Hyperpolarize postsynaptic cell
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What causes IPSP?
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Opening Cl channels
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What are the 2 types of summations?
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Spatial, temporal
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Norepi is the primary NT release from?
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postganglionic sympathetic neurons
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Binds to which receptors?
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alpha, beta
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Removed from synapse by? 2
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MAO, COMT
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Its metabolites?
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DOMA, NMN, MOPEG, VMA
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Epi is secreted from?
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Adrenal medulla
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Dopa is metabolized by? 2
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MAO, COMT
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D1 Receptors are?
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Gs
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D2 receptors are?
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Gi
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2 types of glu receptors are?
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Ionotropic and metabotropic
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GABA-A receptor work by?
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Incr Cl conductance
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GABA-B receptor work by?
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Incr K conductance
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Gly receptor work by?
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Incr Cl conductance
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Skeletal muscle
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16
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Z line is?
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lines that delineate sarcomere boundary
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M line is?
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Middle of sarcomere
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I band is?
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Only actin filaments
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H band is?
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Only myosin filaments
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A band is?
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Both actin and myosin filaments
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Role of troponin T
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Attaches troponin to tropomyosin
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Role of troponin I
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Inhibit myosin-actin interaction
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Role of troponin C
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Binds Ca to allow myosin-actin interaction
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Role of T tubules?
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Open extracellular space that carries depolarization from membrane inside
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Where are T tubules located?
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At A-I jxn
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Role of Ca-ATPase pump (SERCA)
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Keeps intracellular Ca low
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Role of calsequestrin
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loosely binds Ca inside SR
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What R on the SR allows for Ca release?
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Ryanodine R (RYR)
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ATP cycle steps? 5
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No ATP bound so myosin head stuck to actin -> ATP binding cause release -> myosin displaced to + side -> ATP hydrolysis -> Power stroke
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Mechanism of tetanus?
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Repeat stimulation cause xs Ca release -> muscle not relax
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Mechanism of rigor mortis?
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No ATP bound so myosin head stuck to actin
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Isometric contractions occur when?
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Muscle length (preload) is constant
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Isotonic contractiosn occur when?
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Load (afterload) is constant
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Passive tension is?
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developed by stretching muscle to different lengths
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Total tension is?
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When muscle stim to contract at different lengths
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How calculated active tension?
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Total - Passive
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Active tension represents
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active force developed from contraction; proportional to # cross-bridges
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As afterload increase, the velocity of shortening
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decreases
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Smooth muscle
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20
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Multi-unit SM present in?
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Iris, ciliary muscle, vas deferens
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Unitary SM is present in?
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Uterus, GI, ureter, bladder
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Activity in unitary SM is
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spontaneous
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Vascular SM acts like?
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single and mult-unit
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Ca in SM binds to? Steps after? 5
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Ca-calmodulin -> incr MLCK -> phos myosin light chains -> allows binding to actin -> cross-bridge
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