Fenestration & Endothelial Transport

A cell membrane is a phospholipid bilayer with hydrophilic heads projecting outwards and lipid tails facing each other. Smaller or lipid soluble molecules can easily move in and out of the cell membrane through process of simple diffusion. However, lipid insoluble or hydrophilic molecules require specific carriers for their transportation across the cell membrane. Proteins are embedded in this phospholipid bilayer to move hydrophilic or larger molecules in and out of the cell membrane. This proposed model is called fluid-mosaic model of the cell membrane.