Diuresis used to increase urine output and decrease extracellular fluid volume. Substances in the circulation can also increase the amount of circulating fluid by increasing the osmolarity of the blood. This has the effect of pulling water from the interstitial space, making more water available in the blood and causing the kidney to compensate by removing it as urine. In hypotension, often colloids are used intravenously to increase circulating volume in themselves, but as they exert a certain amount of osmotic pressure, water is therefore also moved, further increasing circulating volume. As blood pressure increases, the kidney removes the excess fluid
Water organ in ancient Greek is often imagined as an automatic organ, but there is no source evidence for it. A hydraulis is an early type of pipe organ that operated by converting the dynamic energy of water () into air pressure to drive the pipes (). Hence its name hydraulis, literally "water (driven) pipe (instrument)." It is attributed to the Hellenistic scientist Ctesibius of Alexandria, an engineer of the 3rd century BC. The hydraulis was the world's first keyboard instrument and was the predecessor of the modern church organ. Unlike the instrument of the Renaissance period, which is the main subject