Tympanic membrane retraction commercially available devices (e.g. Otovent and Ear Popper). A ventilation tube, also known as a tympanostomy tube or a grommet, may be placed through the eardrum to equalize middle ear pressure. Although this intervention may be effective, research has not yet shown whether it provides better results than simple observation. Further weakness or perforation of the eardrum may occur. These are intended to improve Eustachian tube function. Adenoidectomy can improve middle ear function and nasal steroid sprays can reduce adenoid size but it is not known whether these treatments alter tympanic membrane retraction. Enlargement of the Eustachian tube opening in
Cell membrane concentration in order to equilibrate the membrane. It is considered a passive transport process because it does not require energy and is propelled by the concentration gradient created by each side of the membrane. Such a concentration gradient across a semipermeable membrane sets up an osmotic flow for the water. Osmosis, in biological systems involves a solvent, moving through a semipermeable membrane similarly to passive diffusion as the solvent still moves with the concentration gradient and requires no energy. While water is the most common solvent in cell, it can also be other liquids as well as supercritical liquids and