Renal physiology (Latin rēnēs, "kidneys") is the study of the physiology of the kidney. This encompasses all functions of the kidney, including maintenance of acid-base balance; regulation of fluid balance; regulation of sodium, potassium, and other electrolytes; clearance of toxins; absorption of glucose, amino acids, and other small molecules;  regulation of blood pressure; production of various hormones, such as erythropoietin; and activation of vitamin D.
Much of renal physiology is studied at the level of the nephron, the smallest functional unit of the kidney. Each nephron begins with a filtration component that filters the blood entering the kidney. This filtrate then flows along the length of the nephron, which is a tubular structure lined by a single layer of specialized cells and surrounded by capillaries. The major functions of these lining cells are the reabsorption of water and small molecules from the filtrate into the blood, and the secretion of wastes from the blood into the urine. Proper function of the kidney requires that it receives and adequately filters blood. This is performed at the microscopic level by many hundreds of thousands of filtration units called renal corpuscles, each of which is composed of a glomerulus and a Bowmans capsule. A global assessment of renal function is often ascertained by estimating the rate of filtration, called the glomerular filtration rate (GFR). Formation of urine
The kidneys ability to perform many of its functions depends on the three fundamental functions of filtration, reabsorption, and secretion, whose sum is called renal clearance or renal excretion.
Novolin is the brand name of three distinct insulin-containing products manufactured by Novo Nordisk:

Novolin 70/30, an insulin preparation containing mixed NPH and regular insulin, respectively
Novolin N, an insulin preparation containing NPH insulin
Novolin R, an insulin preparation containing regular insulin

See also
Insulin (medication)


== References ==