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29 Cards in this Set
- Front
- Back
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What kind of ions are found inside the cell most commonly? (ICF)
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K+ and negatively charged proteins
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What kinds of ions are most commonly found outside the cell in the ECF?
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Na+
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Which ions can easily pass through the membrane?
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K+ passes easily, while Na+ sort of passes, but not well
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What are the two requirements for developing a diffusion potential?
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this requires different concentrations of an ion across the PM
And requires selective permeability of the membrane. (only allows some ions to cross) |
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In the creation of diffusion potentials, is there a measurable change Ion concentrations on either side?
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NO there is not. Extremely small quantities may cross, but they create huge changes in voltage
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What is equilibrium potential?
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This is the electrical force (diffusion potential) that directly opposes the tendency of an ion to flow down its concentration gradient
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When does net movement of ions stop?
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this occurs when the chemical (concentration) and electrical (charge based) forces are balanced across a membrane. Determined by Ion Concentrations
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What determines the magnitude of a potential across a membrane?
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The Magnitude of the concentration gradient (aka concentrations across the membrane) DIRECTLY control the potential
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What is the E(ion) of K+?
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-90mV
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What types of ions actually create the electrochemical gradient, that produces a membrane potential?
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only ones that the membrane is permeable to
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what is the E(ion) of Na+
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+65mV
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What is the formula for the nernst equation, and what information does it give us?
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This gives us the equilibrium potential for an ion @ given concentrations across a membrane. (what the charge will be, if these concentrations exist)
E(ion)= (60/z) * Log ([ion out]/[ion in]). with z= the charge of the ion |
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What is the Eion of Cl-?
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-90mV
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What is the Eion of Ca2+?
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+120 mV
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what is the Eion of Na+?
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+65 mV
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what is the E ion of K+?
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-90mV
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Is there a membrane potential in non-excitable tissues?
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yes there is, and it is constant
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How do K+ and Na+ effect resting membrane potentials?
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the variable permeability to K+ and Na+, as well as their different E ions, lead to a resting membrane potential of -70mV.
K+ is the most permiable ion, so it has the greatest effect on E membrane. Leading the Emembrane to be closest to K+ E ion. |
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How is E membrane calculated?
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by using Ionic Ohm's Law
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What does Ionic Ohm's Law state? And what is it used to determine?
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E membrane= (G(ion1)*E(ion1)+G(ion2)*E(ion2)+...)/(G(ion1)+G(ion2)...)
This is used to find how ions affect the membrane potential, based on their concentrations (leading to Eion) and membrane permeability (conductance) (G) |
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An ion with high/low conductance will have the greatest effect on membrane potential?
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high conductance (in the extreme low...non penetration ions do not contribute to conductance at all)
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How does hypertension affect permeability/conductance?
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This can lead to an increase in the insertion/opening of Ca2+ channels, leading to depoloarizaion (with its +120mV Eion). Leading to smooth muscle contraction
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Regarding K+ and Na+, how does affecting the permeability of the cell in this manner affect membrane potential? Increasing the Permeability of K+
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This would drive the membrane potential towards K+'s Eion, so nearing -90mV
Hyper-polarizing |
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Regarding K+ and Na+, how does affecting the permeability of the cell in this manner affect membrane potential? decreasing the permeability of K+
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this would allow Na+ to exert a greater effect, and drive the E membrane towards Na+'s Eion of +65mV
depolarizing |
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Regarding K+ and Na+, how does affecting the permeability of the cell in this manner affect membrane potential? Increasing the permeability of Na+?
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this would drive E membrane towards Eion of Na+....so it would depolarize, going more to Na+'s +65mV Eion
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Naloxone
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1. Opiod receptor antagonist.
2.Not effective orally, given IV. Short duration of action (1-2 hr). 3. Repeated injections often given for reversal of opiod OD. |
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What is the primary mechanism of maintaining the resting membrane potential?
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the DIFFUSION of ions down their concentration gradients! Via Background channels
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How much does active transport by the Na+/K+ affect RMP?
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only about 5-20mV
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What kinds of toxins can affect the Na+-K+ pump?
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Cardiac Glycoside; ouabain
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