Diffusion net movement is from an area of higher concentration to an area of lower concentration of the particle. Greater difference in concentration, faster rate of diffusion- this difference is concentration gradient. Diffusion occurs down conc gradient and increase in temp increases rate of diffusion
net movement= particles moving in - particles moving out
dissolved substances move into and out of body cells by diffusion across cell membrane, such as simple sugars like glucose and gases like oxygen and co2 and waste products like urea from breakdown of amino acids in liver. the urea passes from liver cells into blood plasma and excreted by kidneys Oxygen needed for respiration passes from air in lungs into red blood cells through cell membranes by diffusion down conc gradient and then moves by diffusion from blood cells into cell of body where needed. diffusion of oxygen and carbon dioxide in opposite directions in lungs is gas exchange.
most common adaptation for cell to make diffusion easier and more rapid is to increase surface area of cell membrane by folding it up so area over which diffusion can take place is greatly increased so rate is also increased so more of substance moves in given time
