thumb|300px|right|this illustration demonstrates the normal kidney physiology. it also includes illustrations showing where some types of diuretics act, and what they do. renal physiology (latin rÄnÄs, "kidneys") is the study of the physiology of the kidney. this encompasses all functions of the kidney, including reabsorption of glucose, amino acids, and other small molecules; regulation of sodium, potassium, and other electrolytes; regulation of fluid balance and blood pressure; maintenance of acid-base balance; the production of various hormones including erythropoietin, and the 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 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 bowman's capsule. a global assessment of renal function is often ascertained by estimating the rate of filtration, called the glomerular filtration rate (gfr). ==functions of the kidney== the functions of the kidney can be divided into three groups: secretion of hormones, gluconeogenesis and extracellular homeostasis of ph and blood components. the nephron is the functional unit of the kidney. ===secretion of hormones=== *secretion of erythropoietin, which regulates red blood cell production in the bone marrow. *secretion of renin, which is a key part of the renin-angiotensin-aldosterone system. *secretion of the active form of vitamin d (calcitriol) and prostaglandins. ===gluconeogenesis=== the kidney in humans is capable of producing glucose from lactate, glycerol and glutamine. the kidney is responsible for about half of the total gluconeogenesis in fasting humans. the regulation of glucose production in the kidney is achieved by action of insulin, catecholamines and other hormones. renal gluconeogenesis takes place in the renal cortex. the renal medulla is incapable of producing glucose due to absence of necessary enzymes. ===extracellular homeostasis=== the kidney is responsible for maintaining a balance of the following substa
Renal_physiology