Tympanic part of the temporal bone upper part of the posterior wall by the squama. Its inner end is closed, by the tympanic membrane which originates from the tympanic sulcus; the upper limit of its outer orifice is formed by the posterior root of the zygomatic process, immediately below which there is sometimes seen a small spine, the "suprameatal spine", situated at the upper and posterior part of the orifice. The auditory bulla (pl. bullae) is a hollow bony structure on the ventral, posterior portion of the skull that encloses parts of the middle and inner ear. In most species, it is formed by the tympanic
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