Friday, March 30, 2012 CC-BY-NC
Renal: Anatomy of kidney

Maintainer: admin

1Functions of Kidneys

  • regulation of water, inorganic ion balance, acid-base blance
  • removing foreign particles or metabolic waste products from the blood and excreting them into urine
    • (kidney makes pee)
  • produce hormones and enzymes:
    • erythropoietin: hormone that controls erythrocyte production
    • renin: enzyme that control formation of antgiotensin (which influences blood pressure and sodium balance... will see later)
    • 1,25-dihydorxyvitamine D : vitamind that influences calcium balance

2Anatomy of kidney


  • paired organs, 150g each.
  • located behind peritoneum on either side of the vertebral column against the posterior abdominal wall
  • has ureter which send urine to bladder.

2.2organ itself

  • outer to inner: renal cortex, renal medulla (like pyramid), renal pelvis.
  • has ureter, renal artery, and renal vein
  • afferent arteriole : blood supply to nephron (functional unit of kidney).
    • arcuate artery : line the boundary between renal cortex and medulla
    • interlobar artery: between pyramid (renal medulla)
    • interlobular artery: in renal cortex. perpendicular to arcuate artery.


  • each kidney has ~1 million nephrons (smallest functional unit)
  • nephron consists of :
    • renal corpuscle
      • glomerulus (capillary loops) : always entirely in cortex.
      • bowman's capsule
    • tubule
  • vascular supply:
    • after blood enters into glomerulus via afferent arteriole, it leaves via efferent arteriole.
    • efferent arteriole then supplies the tubule.

2.4take a trip from glomerulus to bladder

  • glomerulus -> bowman's space in bowman capsule ->
  • proximal convoluted tubule (which starts in cortex) ->
  • proximal straight tubule (partially in medulla)
  • Loop of henle -->
    • descending thin limb
    • ascending thin limb (we don't talk about its function)
    • ascending thick limb
  • distal convoluted tubule (starts where glumerolus touches tubule. ends where tubule of other nephrons are merging).
  • collecting duct
  • renal pelvis
  • ureter
  • bladder.


  • where distal convoluted tubule touches afferent arteriole originating from the glomerulus, there are a bunch of cells (juxtaglomeruluar cells) that regulate secretion.
  • glomeruluar capillary wall is covered by foot processes of potocyte.
  • capillary is also fenetrated.
    • it's a filtration barrier:
      • plasma can diffuse through fenetrations, glomerulus BM (basement membrane), filtration slits between foot processes of potocytes (visceral endothelial cells), and go into capsular space.
      • glomerulus filter blood to make urine.

2.6summary of where everything is

  • cortex:
    • renal corpuscle (always always in cortex)
    • proximal tubule (convoluted and straight)
  • medulla:
    • Henle's loop (has 3 parts)
      • descending thin limb
      • ascending thin limb
      • thick ascending limb (has macula densa at the end)
  • cortex again:
    • distal convoluted tubule
  • back to medulla:
    • collecting duct (where nephrons merge together.)

3Renal formation: Basics

  • glomerular filtration (in glomerulus)
    • filtrate is cell-free (you don't excrete cells)
    • filtrate contains all substances (except proteins) as those present in plasma. (more details later)
  • tubular secretion and reabsorption (in tubule)
    • as filtrate passes through tubule, its composition is altered by movement of substances
      • reabsorption : substances move from tubule to peritubular capillaries
      • secretion : bllod to tubules
    • types of secretion/reabsorption: (examples)
      • PAH (para-amino-hippurate): some is filtered into glomerus and the rest is dumped in the urine by 100% secretion inot the tubule after glomerulus) -- > 100% excretion
      • sodium, water : some is filtered at glomerulus (i.e. going into the tubule) and then reaborption occurs in the tubule, taking some of that back into the blood --> high reabsorption)
      • glocose: amount filtered in the glomerous is totally reabsorpted in tubule. --> 100% reabsorption
  • rate of filtration, reabsorption, or secretion is subject to physiological control.