Several mechanisms facilitate the penetration of chemicals through biological barriers. These include:
Passive Diffusion: The most common mechanism, where chemicals move from an area of higher concentration to an area of lower concentration without expending energy. Facilitated Diffusion: Involves the movement of chemicals via carrier proteins or channels, still following the concentration gradient but requiring specific transporters. Active Transport: This energy-dependent process allows chemicals to move against their concentration gradient through specific transport mechanisms. Endocytosis: A process where cells engulf molecules, allowing them to enter the cell in vesicles.
