2 Facilitated Diffusion >Definition: >the diffusion of lipid insoluble or water soluble substance >across the membrane >down their concentration gradients by aid of membrane proteins >(carrier or channel) >Substances: K+, Nat, Cazt, glucose amino acid urea etc29 2 Facilitated Diffusion ➢Definition: ➢the diffusion of lipid insoluble or water soluble substance ➢across the membrane ➢down their concentration gradients by aid of membrane proteins ➢ (carrier or channel) ➢Substances: K+ , Na+ , Ca2+, glucose, amino acid, urea etc