Physiology 3140A Chapter Notes -Saxitoxin, Bmw K100, Proprioception
4 Feb 2014
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V (10-6 v) mv (10-3 v) pa (10-12 a) na (10-9 a) G (109 ) ps (10-12 s) ns (10-9 s) mv = millivolt na = nanoampere pa = picoampere. Surface the ball rolls on = resistance: steeper the hill the lower the resistance & faster the ball will move, pressure & water flow are analogous to voltage & current respectively. In excitable cells current is carried by ions (versus electrons in metals) Ions = cations (+ve) & anions (-ve: cations: na+, k+, ca2+, mg2, anions: cl- & hco3. Ohms law: applies to electric circuits, current (i) passing through a conductor is directly proportional to the voltage difference (v) across the conductor & inversely proportional to the resistance (r) of the conductor. **not all ligand-gated channels have 2 binding sites. Physical properties of ions: selectivity of ion channels is based on: size of ions & their charges, charge density, size & charge of an ion.
