Urinary System

Components

  • two kidneys (retroperitoneal)
  • two ureters (each partially retroperitoneal)
  • urinary bladder
  • urethra

    • Functions

  • maintains homeostasis
  • maintains water balance
  • maintains salt balance
  • eliminates waste

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    Important Terms
    Hilum concave medial portion of the kidney where renal A and V and ureter enter or exit
    Cortex outer portion of the frontally bisected kidney; contains Bowman's capsules
    Medulla inner portion of the frontally bisected kidney; contains renal columns and renal pyramids as well as the Loops of Henle and collecting ducts
    Renal Pyramids cone-shaped areas in the renal medulla with apex pointing toward hilum; contain Loops of Henle
    Renal Columns areas of the medulla between the renal pyramids; arterioles and venules are notable here
    Nephron the physiological unit of the kidney; it includes Bowman's capsule with glomerulus, proximal convoluted tubules, loop of Henle, and distal convoluted tubules
    Bowman's Capsule first part of the nephron; it encircles the glomerulus and collects plasma expressed by the glomerular capillaries
    Glomerulus capillary network within the Bowman's capsule
    Proximal Convoluted Tubules first section of the nephron after Bowman's capsule
    Loop of Henle this consists of a descending, loop, and ascending portion; as fluid passes through the loop it is surrounded by a capillary system (vasa recta) which reabsorbs selected nutrients into the blood.
    Distal Convoluted Tubules final section of the nephron; these tubules gather around the Bowman's capsule of their own nephron
    Collecting Duct a shared passageway; many nephrons empty urine into a single collecting duct
    Minor Calyx the first, small chamber the urine enters after leaving the collecting duct
    Major Calyx a larger collecting area for urine, each receiving material from several minor calyces
    Renal Pelvis largest chamber within the kidney; urine collects here from the major calyces
    Ureter Tubelike passageway from each kidney to the urinary bladder; the first portion of each ureter is retroperitoneal in position meaning that it is behind the peritoneum
    Urinary Bladder hollow organ with rugae; collects and stores urine temporarily
    Urethra passageway from the bladder to the exterior

    Pathway of Blood through the Kidney

  • renal artery (followed by segmental and lobar arteries)
  • interlobar artery
  • arcuate artery
  • interlobular artery
  • afferent arteriole
  • glomerulus
  • efferent arteriole
  • vasa recta
  • arteria recta
  • vena recta
  • interlobular vein
  • arcuate vein
  • interlobar vein
  • renal vein
    • Notice that the blood passes through two sets of capillaries in this scheme. The first set is the glomerulus and the second is the vasa recta. Until blood is headed back to the heart from the final set of capillaries it is said to be in the arterial system.