Getty/Jason Hosking. A niche is a term that is used in ecological biology to define an organism's role in an ecosystem. Not only does a niche include the environment a given organism lives in, it also includes the organism's job in that environment.
Perilymph (also known as Cotunnius' liquid, and liquor cotunnii) is an extracellular fluid located within the cochlea (part of the inner ear) in two of its three compartments: the scala tympani and scala vestibuli. The ionic composition of perilymph is comparable to that of plasma and cerebrospinal fluid. The major cation (positively charged ion) in perilymph is sodium: The values of sodium and potassium concentration in the perilymph are 138 mM and 6.9 mM, respectively.
Pericardial effusion, sometimes called fluid around the heart, causes an accumulation of fluid between the heart and the pericardium, the heartâs lining. When the volume of fluid in the pericardium gets too high, pericardial effusion puts pressure on the heart, reducing the heartâs function. Pericardial Effusion Causes.