BIOS 281 Lecture 3 Membrane Transport and Potentials

Voltage gated na channels open during the steep

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Unformatted text preview: the inside of the cell is nega0ve rela0ve to the outside.) Resting Membrane Potential You must be connected to the internet to run this animation Maintaining the RMP •  A cell that exhibits an RMP is said to be polarized. –  In this state, the cell is “primed” - it is ready to produce an ac0on poten0al. In order to do so, graded poten-als must first be produced in order to depolarize the cell to threshold. •  A graded poten0al occurs whenever ion flow in mechanically gated or ligand- gated channels produce a current that is localized – it spreads to adjacent regions for a short distance and then dies out within a few millimeters of its point of origin. Graded Poten0als •  From the RMP, a s0mulus that causes the cell to be less nega0vely charged with respect to the extracellular fluid is a depolarizing graded poten-al, and a s0mulus that causes the cell to be more nega0vely charged is a hyperpolarizing graded poten-al (both are shown in this diagram.) Graded Poten0als •  Graded poten0als have different names depending on the type of s0mulus and where they occur. They are voltage variable ap0tudes that can be added together (summate) or cancel each other out – the net result is a larger or smaller graded poten0al....
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This note was uploaded on 11/12/2013 for the course BIOS 281 taught by Professor Varamini during the Fall '12 term at Biola University.

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