Question

Discuss resting membrane potential, membrane permeability, electrochemical gradients, Nernst equation, Goldman-Hodgkin-Katz equation.

Answer 1

Resting membrane potential (RMP) is the charge difference across the cell membrane when the cell is at rest. The resting membrane potential is determined by the concentration gradients of ions across the membrane and by membrane permeability of each type of ion.

Membane permeability can be defined as passive diffusion rate of permeated molecules across a membrane. Permeability is of three types- absolute, effective and relative permeability. The permeability of a membrane is affected by polarity, electric charge and molar mass of the molecules that diffuse through it.

Electrochemical gradients is the driving force of ion movement acroos the membrane. It depend upon the concentration difference and the electrical difference on each side of the membrane.It determines the direction an ion moves by diffusion or active transport across a membrane.

Nernst equation provides a relation between the cell potential of an electrochemical cell , the standard potential, temperature and the reaction quotient. this equation determines the cell potential under non standard conditions.

GOLDMAN HODGKIN KATZ equation determines the reversal potential across a cell membrane , taking in account all the ions that are permeant through the membrane. It calculates the electrical equilibrium potential across the membrane in presence of more than one ion, it was derived from nernst equation.