NEUR 3200 Lecture Notes - Lecture 3: Nernst Equation, Voltage Clamp, Tetrodotoxin
8 Mar 2016
School
Department
Course
Professor
Document Summary
Change in ion concentration doesn"t really alter the concentration gradient and has a minimum affect on intracellular. Prolonged activity (long activity such as seizures) impacts extracellular potassium (k) concentration. Potassium rises due to potassium efflux repolarizing the membrane after every action potential. Increased extracellular potassium causes a change in the equilibrium potential for potassium. Resting potential more likely to be exceeding threshold potential, increasing likelihood of action potentials. (prolonged seizures) Opening of k channels leads to k leaving the cell. Opening of cl channels leads to cl- entering the cell. Equilibrium potential for sodium na = +55. Opening sodium channels leads to sodium entering the cell causing intracellular charge to be more negative = If the membrane permeability to sodium (na) suddenly became 5 times greater than the permeability to potassium (k), then the change in equilibrium potential would be major. In an action potential, the membrane briefly becomes massively permeable to sodium.
