front 1 electroactive | back 1 neural membrane sensitive to electrical change |
front 2 hydration shell | back 2 bigger molecules can pass if energetically favorable, eg. water molecules surrounding molecules such as K+, easier to pass through than Na+ since energetically favorable to do so |
front 3 leak channels | back 3 persistently open |
front 4 voltage gate channel | back 4 sensitive to electrical potential, depends on membrane charge |
front 5 ligand-gated ion channels | back 5 iontropic receptors, open in response to ligands (neurotransmitters) |
front 6 variety of channels | back 6 sensory systems, respond to unique stimuli eg. skin, hair cells... |
front 7 dynamic equilibium | back 7 constant movement of ions, no net movement of charge, balanced |
front 8 Nernst Equation (simplified) | back 8 Ex = 58 log ([x]o/[x]i) |
front 9 Nernst Equation | back 9 Ex = RT/zF ln([x]o/[x]i); calculates reversal potential for given ion x; assumes all channels are open |
front 10 R | back 10 ideal gas constant; 8.314 J/K*mol; way to convert # of molecules and energy that molecules exert |
front 11 T | back 11 temperature; ~292K |
front 12 z | back 12 electrical charge; predict direction of ion movement based on ion charge; represents influence exerted by electrical gradient Na+ and K+; z = +1 Cl- = -1 Ca2+ = +2 |
front 13 F | back 13 faradays constant; 96,485 coulombs/mol |
front 14 Goldman-Hodgkin-Katz equation (GHK equation) | back 14 combines Nernst equation w/ 3 relevant ions (K+, Na+, Cl-) gives value of membrane potential Vm; explains how movement of Na+ across membrane causes cell to become more positive. |
front 15 p | back 15 permeability; the higher the permeability the higher the Vm is to the Ex of that ion |
front 16 resting membrane potential | back 16 -70mV, dominated by pk = 1, pcl = 0.55, pNa = 0.04 -80mV, -60mV, +55 mV |
front 17 threshold | back 17 around -55 mV |
front 18 action potential | back 18 short lasting change in membrane potential that travels down axon; driven by ion movement |
front 19 graded potentials | back 19 subthreshold changed in Vm |
front 20 depolarization | back 20 Vm becomes more positive |
front 21 hyperpolarization | back 21 Vm becomes more negative |
front 22 steps of the action potential | back 22 no data |
front 23 1. depolarization from incoming neurons | back 23 neurotransmitters from presynaptic neurons cause ion movement via postsynaptic ligand-gated ion channels. postsynaptic potentials PSPs - small deviations in membrane voltage, release of EPSPs cause small depolarizations, IPSPs cause small hyperpolarizations |
front 24 spatial summation | back 24 2 EPSPs from 2 adjacent inputs |
front 25 temporal summation | back 25 multiple EPSPs from same input close in time |
front 26 2. opening of voltage-gated Na+ channels | back 26 depolarization past threshold opens these channels leading to the influx of Na+ into the cell leading to further depolarization with a peak of around +40 mV |
front 27 3. opening of voltage-gated K+ channels | back 27 large depolarization leads to a more positive cell, this positive charge pushes K+ out of the cell; the opening of these channels leads to the Vm becoming more negative than resting potential (closer to Ek) |
front 28 4. inactivation of voltage-gated Na+ channels | back 28 when cell reaches + potential, channels innactivate, prevents movement of excitatory, depolarizing Na+ ions |
front 29 5. deactivation of voltage - gated K+ channels | back 29 cell becomes negative again, since K+ leaves the cell. hyperpolarization stops, membrane potential returns to equilibrium of resting potential |
front 30 shapes of action potential | back 30 depolarization, repolarization, and afterhyperpolarization |
front 31 1. depolarization | back 31 Vm becomes more positive due to Na+ influx K+ channels open |
front 32 2. repolarization | back 32 Na+ channels inactivate K+ driven out of the cell Vm becomes more negative |
front 33 3. afterhyperpolarization | back 33 gradual deactivation of K+ channels |
front 34 absolute refractory period | back 34 time window where 2nd action potential cnanot be fired happens because Na+ voltage-gated channels are innactivated |
front 35 relative refractory period | back 35 exists on a gradient, more difficult to fire action potential Na+ channels reset @ inactive state K+ channels still open, movement still happening movement of K+ hinders depolarization |
front 36 action potential is unidirectional | back 36 1. Na+ moves to lower conc. unlikely to move backward 2. previous patch is in absolute refractory period, impossible for action potential to travel backwards |
front 37 myelin | back 37 layer of lipid coatory axon. increases conduction velocity, speed by which action potential travels down length of axon. works by blocking K+ leak channels in membrane causes + charge to be unable to exit cell signal moves rapidly |
front 38 saltatory conduction | back 38 AP jumps from node to node |