Search results
Results from the WOW.Com Content Network
The process of osmosis over a semipermeable membrane.The blue dots represent particles driving the osmotic gradient. Osmosis (/ ɒ z ˈ m oʊ s ɪ s /, US also / ɒ s-/) [1] is the spontaneous net movement or diffusion of solvent molecules through a selectively-permeable membrane from a region of high water potential (region of lower solute concentration) to a region of low water potential ...
One example of passive diffusion is the gas exchange that occurs between the oxygen in the blood and the carbon dioxide present in the lungs. [3] Facilitated diffusion is the movement of polar molecules down the concentration gradient with the assistance of membrane proteins. Since the molecules associated with facilitated diffusion are polar ...
1. Passive osmosis and diffusion: Some substances (small molecules, ions) such as carbon dioxide (CO 2) and oxygen (O 2), can move across the plasma membrane by diffusion, which is a passive transport process. Because the membrane acts as a barrier for certain molecules and ions, they can occur in different concentrations on the two sides of ...
Diffusion of solvents, such as water, through a semipermeable membrane is classified as osmosis. Metabolism and respiration rely in part upon diffusion in addition to bulk or active processes. For example, in the alveoli of mammalian lungs , due to differences in partial pressures across the alveolar-capillary membrane, oxygen diffuses into the ...
Transcellular transport often involves energy expenditure whereas paracellular transport is unmediated and passive down a concentration gradient, [4] or by osmosis (for water) and solvent drag for solutes. [5] Paracellular transport also has the benefit that absorption rate is matched to load because it has no transporters that can be saturated.
Multicomponent diffusion is diffusion in mixtures, and diffusiophoresis is the special case where we are interested in the movement of one species that is usually a colloidal particle, in a gradient of a much smaller species, such as dissolved salt such as sodium chloride in water. or a miscible liquid, such as ethanol in water.
Since Osmosis is a passive process, like facilitated diffusion and simple diffusion, it does not require the use of ATP. Osmosis is important in regulating the balance of water and salt within cells, thus it plays a critical role in maintaining homeostasis. [ 15 ]
The word diffusion derives from the Latin word, diffundere, which means "to spread out". A distinguishing feature of diffusion is that it depends on particle random walk, and results in mixing or mass transport without requiring directed bulk motion. Bulk motion, or bulk flow, is the characteristic of advection. [1]