Diffusion
• Diffusion is a biological process pertaining to the movement of particles from an area of high concentration to an area of low concentration.
• It is a passive process, meaning it does not require energy for the movement to occur.
• This process happens automatically in liquids and gases as particles are free to move about randomly.
• The rate of diffusion is impacted by various factors including the temperature, concentration gradient, surface area, the type of substance, and the distance over which diffusion occurs.
• A greater temperature, larger surface area, steeper concentration gradient, greater solubility in lipid, and shorter distance enhances the rate of diffusion.
• Diffusion is crucial for many biological processes such as the absorption of nutrients and oxygen into cells, and the removal of waste products out of cells.
• Oxygen and carbon dioxide in particular are two gases that move in and out of cells by diffusion.
• Simple diffusion directly through the cell membrane is how smaller molecules, such as oxygen and water, usually move.
• The process of diffusion occurs until equilibrium is reached, where the particles are equally distributed and there is no concentration gradient.
• In human physiology, the diffusion of water is known as osmosis.
• The diffusion that occurs alongside carrier proteins and channels is called facilitated diffusion.
• Osmosis, facilitated diffusion, and simple diffusion are all key components of passive transport mechanisms in cells.
• Diffusion is crucial in various biological systems, like in the alveoli for gas exchange, in kidneys for filtration and reabsorption, and in the small intestine for nutrient absorption.