In this Article. In this Article. A solitary pulmonary nodule (SPN) is a single abnormality in the lung that is smaller than 3 cm in diameter. Generally, a pulmonary nodule must grow to at least 1 cm in diameter before it can be seen on a chest X-ray.
Osmosis is the scientific process of transferring fluid between molecules. When molecules move in and out of a cell to achieve the same concentration of something, like salt, on both sides, then osmosis is happening.
Osmosis. 1  Special term used for the diffusion of water through a differentially permeable cell membrane. 2  Water is polar and able to pass through the lipid bilayer. 3  Transmembrane proteins that form hydrophilic channels accelerate osmosis, but water is still able to get through membrane without them.