Cell Membrane Permeability

Cell membrane permeability refers to the ability of the cell membrane to allow certain substances to pass through while restricting others. This property is crucial for maintaining cellular homeostasis, enabling cells to regulate their internal environment despite changes in external conditions. The selective permeability of the cell membrane arises from its structure: the core of the membrane is a phospholipid bilayer with hydrophobic tails facing inward and hydrophilic heads facing outward. For substances that cannot diffuse directly through the lipid bilayer, specific transmembrane proteins act as transporters or channels, facilitating diffusion down concentration gradients or actively transporting substances against gradients using energy.