Nephron

• Nephron

  • Birth: kidneys have ~1 million microscopic nephrons (’renal tubules’)
  • Decreases with age
  • Osmoregulation + urine formation
  • Cortex + medulla tissue
  • Nephrons’ DCT opens to collecting duct
  • Several nephrons share
  • Join at kidneys’ pelvis
  • Empty urine to ureter
  • Renal artery
  • Oxygenated
  • Arterioles
  • Each nephron supply by afferent arteriole
  • To capillary network; glomerulus (capillary knot)
  • Bowman’s capsule
  • Blood drains to efferent arteriole (narrower lumen)
  • Then to capillary network around PCT, loop of Henle (Vasa recta), DCT + collecting duct
  • Drains to venules then renal vein
• Nephron Parts

  Distal Convoluted Tubule (DCT)

  • Continuous w/ loop of Henlé’s ascending limb
  • Second coiled renal tubule
  • Cortex
  • Blood capillaries surround
  • Join collecting duct at most distal end

  Loop of Henlé

  • Descending limb + ascending limb
  • Walls permeabilities differ
  • Wider/narrower sections
  • Start cortex, to medulla
  • Surround by vasa recti capillaries

  Proximal convoluted tubule (PCT)

  • First coiled renal tubule
  • Cortex
  • Surround by capillaries from efferent arteriole
  • Single-cell cuboidal epithelium wall + brush border
  • Long microvilli
  • Mitochondria; selective reabsorption need ATP
  • Large SA

  Bowman’s Capsule (renal capsule)

  • Cup-shape
  • Support capillary network (glomerulus)
  • Cortex
  • Ultrafiltration (high pressure)
  • Make glomerular filtrate
  • Forced out except erythrocytes, leukocytes, etc
  • Too big for basement membrane