Membrankapazität

Membrankapazität, often translated as membrane capacitance, refers to the electrical capacitance of a biological membrane. This capacitance arises from the lipid bilayer structure of the membrane, which acts as a dielectric material separating two conductive solutions, the intracellular and extracellular fluid. Essentially, the membrane can store electrical charge, similar to a parallel plate capacitor. The value of the membrane capacitance depends on the area of the membrane and the thickness and dielectric properties of the lipid bilayer. In biological cells, the capacitance is typically measured in farads per square meter (F/m²) or picofarads per square micrometer (pF/µm²).

This property is significant because it influences how the membrane responds to changes in voltage. When the voltage across the membrane changes, charge must accumulate or dissipate on either side of the membrane to alter the membrane potential. This process takes time and is governed by the membrane capacitance. Therefore, membrane capacitance plays a crucial role in phenomena such as the propagation of action potentials in neurons and the electrical excitability of cells. It contributes to the time constant of the membrane, which dictates how quickly the membrane potential can change. Understanding membrane capacitance is fundamental in fields like electrophysiology and biophysics for analyzing cellular electrical behavior and the function of ion channels.