Physiology of Excitable Cells - Membrane Biophysics
- Created by: Urwa Mogul
- Created on: 19-12-18 19:45
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Clues
- ability of charge to move from inside of cell to out of cell. Increasing Rm increases max response altitude and slows down rise time. decreasing Rm decreases max response altitude and rapid rise time (8, 10, 1)
- cant be predicted precisely, independent behaviour of individual channels (10, 9)
- components of cell membrane similar to passive elements of electric circuits. ion channels correspond to resistor and lipid bilayer acts as capacitor. (7, 10)
- increases conduction velocity of nerve axon because myelin increases Rm and lowers Cm. allows action potential to be conducted very rapidly from one node of Ranvier to next, making AP appear to jump from node to node in form of conduction = SALTATORY (11)
- measure of ability to pass ionic current (s) allows us to see voltage dependent behaviour independent of driving force (11)
- measure value where concentration gradient and electrical gradients balance each other = EA = (58/z)log10(([A]o/[A]i)) - theoretical assumes membrane perfectly selective for that ion (6, 8)
- rapid, all or nothing change in membrane potential, self propagating (6, 9)
- selectivity filter in closed state. Open state - inner helices apart - aperture permitting ions to move through. Closed state - inner helices bundled - narrows pore preventing ions to pass through (3, 7, 6)
- technique of controlling membrane potential and measuring current to rapidly return membrane potential to chosen level, compensates (therefore measures) current. Clamps voltage and providing current equal and opposite - can measure current (7, 5)
- τ=R*C equals time taken for voltage to rise exponentially by 63% of the difference between its initial and final values (4, 8)
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