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Unformatted text preview: Neurons, Drugs membrane potential- difference in charge across the membrane • cytoplasm = negative, extracellular matrix = positive • fixed anions- negatively charged molecules too large to diffuse out of the cell • leak channels and sodium-potassium pump keep positively charged ions out of the cell • equilibrium potential- point where electrical/chemical forces balance out for a certain ion graded potentials- small changes in membrane potentials • casued by activation of gated ion channels (can open in response to stimuli like hormones) • chemical (ligand) gated channel- open when chemicals bind to them o channels open >> change in membrane permeability >> different ions can get in/out • depolarization >> membrane potential becomes less negative • hyperpolarization >> membrane potential becomes more negative • summation- ability of graded potentials to combine • threshold - amount of depolarization needed to create action potential action potential- nerve impulse once voltage-gated ion channels open...
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- Fall '10
- Biology, Nitric oxide