Nephron

• At birth, kidneys have ~1 million microscopic nephrons (’renal tubules’), but number decreases with age; it carries out osmoregulation and urine formation, they’re located in cortex and medulla tissue
• Nephrons’ DCT opens into collecting duct, several nephrons share one, and converge at kidneys’ pelvis, emptying urine into ureter
• Renal artery supply oxygenated blood (branched blood vessel network - arterioles), each nephron supplied by an afferent arteriole; transports into capillary network - glomerulus (capillary knot), in Bowman’s capsule
• Blood from glomerulus drains to an efferent arteriole (narrower lumen than afferent), then to capillary networks surrounding pct, loop of Henle (Vasa recta), dct and collecting duct; then it drains to venules then to renal vein
• Bowman’s Capsule (’renal capsule’): Cup-shaped, supports capillary network (glomerulus), in cortex; responsible for ultrafiltration (high pressure) of blood plasma occurs (produces glomerular filtrate), everything forced out except red and white blood cells, platelets, and large plasma proteins; all too big for basement membrane
• Proximal convoluted tubule (pct): First coiled renal tubule part and longest nephron part, found in cortex and surrounded by capillary network branched from efferent arteriole, it has a single cuboidal epithelial cell layer wall with brush border, long microvilli project in tubule lumen, and many mitochondria as selective reabsorption needs ATP and a large surface area
• Loop of Henlé: Descending limb and ascending limb (walls permeabilities differ, and have wider and narrower sections); both start in cortex but reach medulla, surrounded by vasa recti capillaries
• Distal convoluted tubule (dct): Continuous with loop of Henlé’s ascending limb, second coiled renal tubule part, in cortex, blood capillaries also surround; it joins collecting duct at its most distal end