driving force outwards from the capillary as a whole, which also results in that more fluid exits a capillary than re-enters it. The lymphatic system drains this excess. J. Rodney Levick argues in his textbook that the interstitial force is often underestimated, and measurements used to populate the revised Starling equation show the absorbing forces to be consistently less than capillary or venular pressures. Specific organs Kidneys Glomerular capillaries have a continuous glycocalyx layer in health and the total transendothelial filtration rate of solvent () to the renal tubules is normally around 125 ml/ min (about 180 litres/ day). Glomerular capillary is more familiarly known as the glomerular filtration rate (GFR). In the rest of the body's capillaries, is typically 5 ml/ min (around 8 litres/ day), and the fluid is returned to the circulation via afferent and efferent lymphatics. Lungs The Starling equation can describe the movement of fluid from pulmonary capillaries to the alveolar air space. Clinical significance Woodcock and Woodcock showed in 2012 that the revised Starling equation (steady-state Starling principle) provides scientific explanations for clinical observations concerning intravenous fluid therapy. Traditional teaching of both filtration and absorption of fluid occurring in a single capillary has been superseded by the concept of a vital circulation of extracellular fluid running parallel to the circulation of blood. New approaches to the treatment of oedema (tissue swelling) are suggested. History The Starling equation is named for the British physiologist Ernest Starling, who is also recognised for the Frank–Starling law of the heart. Starling can be credited with identifying that the "absorption of isotonic salt solutions (from the extravascular space) by the blood vessels is determined by this osmotic pressure of the serum proteins" in 1896. See also Renal function References External links Derangedphysiology.com: Starling's Principle of Transvascular Fluid Dynamics Starling's principle of transvascular fluid dynamics | Deranged Physiology Equations of fluid dynamics Cardiovascular physiology Mathematics in medicine