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action potential
brief fluctuation in membrane pontential caused by the rapid opening and closing of voltage-gated ion channels; also known as spike, nerve impulse, or discharge. travel along axons to transfer info. from one place to another in the nervous system
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excitable membrane
any membrane capable of of generating action potentials.
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resting membrane potential
the membrane potential, or membrane voltage, maintained by the cell when it's not generating action potentials; aka resting potential (-65 mV)
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ion selectivity
a property of ion channels that are selectivley permeable to some ions and not to others
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gating
a property of many ion channels, making them open or close in response to specific signals, such as membrane voltage or the presence of neurotransmitters
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ion pump
a protein that transports ions across a membrane at the expense of metabolic energy
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ion
an atom or molecule that has a net electrical charge bc of a difference in the number of electrons and protons
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cation
a positively charged ion
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anion
a negatively charged ion
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phospholipid bilayer
the arranagement of phospholipid molecules that forms the basic structure of the cell membrane. the core of the bilayer is lipid, creating a barrier to water and to water-soluble ions and molecules
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peptide bond
the covalent bond between the amino group of one amino acid and the carboxly group of another
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polypeptide
a string of amino acids held together by peptide bonds
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ion channel
a membrane-spanning protein that forms a pore that allows the passage of ions from one side of the membrae to the other
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diffusion
the temperatuare -dependent movement of molecules from regions of high concentration to low concentration resulting in more even distribution
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concentration gradient
a difference in concentration from one region to another. ionic concentration gradients across the neuronal membrane help determine the membrane potential
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electric current
the rate of movement of electrical charge, symbol (I) measure in amperes; the movement of electrical charge
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electrical potential
the force exerted on an electrically charged particle, represented by the symbol V and measured in volts
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voltage
the force exerted on an electrically charged particle; (v) measure in volts
aka electrical potential or potential difference
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electrical conductance
the relative ability of an electrical charge to migrate from one point to another; (g) measured in siemens (s). conductance is the inverse of resistance.
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electrical resistance
the relative inability of an electrical charge to migrate from one point to another; (R) measured in ohms (W)
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Ohm's law
the relationship between electrical current (I), voltage (V), and conductance (g)
I=gv
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membrane potential
the voltage across a cell membrane (Vm)
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microelectrode
a probe used to measure the electrical activity of cells.
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ionic equilibrium potential or equilibrium potential
the electrical potential difference that exactly balances an ionic concentration gradient, (Eion)
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ionic driving force
the differenc between the real membrane potential, Vm, and the ionic equilibrium potential, Eion.
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nernst equation
a mathematical relationship used to calculate an ionic equilibrium potential
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sodium-potassium pump
an ion pump that removes intracellular Na+ and concentrates intracellular K+, using ATP as its energy source
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calcium pump
an ion pump that removes cytosolic Ca2+
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goldman equation
a mathematical relationship used to predict membrane potential from the concentrations and membrane permeabilities of ions
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depolarization
a change in membrane potential, taking it from the value at rest to a less negative value
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blood brain barrier
a specialization of the walls of brain capillaries that limits the movement of blood borne substances into the extracellular fluid of the brain
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