URINARY TRACT

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URINARY TRACT I The kidney Maria M. Picken
MD, PhD mpicken_at_luc.edu
Renes Latin kidneys nephros Greek kidney
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Outline I the kidney development gross
structure vasculature
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• Objectives
• General objectives
• - to identify the kidneys structures, function
  and location
• - to analyze the relationship between microscopic
  structure and function
• Specific objectives
• 1. Identify elements of the gross and microscopic
  structure of the kidney and analyze the
  relationship between them
• 2. Identify developmental stages of kidney and
  their position
• 3. On gross kidney identify cortex, medulla,
  papillae at apex of medullary minor calyces,
  major calyces, renal pelvis
• 4. Describe the renal blood supply renal artery,
  arcuate arteries, interlobular arteries,
  differences between cortical
• and medullary blood supply, define arterioles
  (afferent and efferent), peritubular capillary
  plexus

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• Retroperitoneum,
• Thoracic vertebra12-Lumbar vertebra3
• 115-170 g (MgtF)
• 11-12 x 5-7.5 x 2.5-3 cm
• Kidneys paired, bean shaped
• Ureters paired
• urinary bladder
• Urethra, male versus female

• Renes Latin kidneys
• Nephros Greek kidney (Nephrology)
• Function
• Filter blood reabsorb nutrients
• Control water, ion, and salt balance of the body
• Maintain acid-base balance of the blood (pH)
• Excrete metabolic wastes (urea and uric acid),
  toxins, drug components
• Secrete hormones (renin, erythropoietin)
• Produce calcitriol (active form of vitamin D
  absorption of dietary calcium into the blood)

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• Kidney development through a series of successive
  phases
• the pronephros (most immature)
• mesonephros
• metanephros, persists as the definitive adult
  kidney
• http//www.meddean.luc.edu/lumen/MedEd/urology/nlr
  endev.htm

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Kidney development - complex

• 3 stages pronephros, mesonephros, metanephros
• cranial to caudal direction followed by ascend
• mesonephric duct comes in contact with cloaca,
  grows cranially as ureteric bud
• ureteric bud metanephros reciprocally induce
  growth, forming kidney
• the kidney ascends
• takes new arterial supply from the aorta, new
  venous drainage into the vena cava
• developmental abnormalities are relatively common
• important in pediatric nephrology

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• Kidney structure bean shaped
• - capsule
• - cortex (outer)
• - medulla (inner)
• - hilum (pelvis, ureter, renal artery, vein)
• Cortex, renal columns (septa) of Bertin
• (cortical tissue on either side of the medullary
  pyramids)
• Medulla divided into several conical pyramids
• Papillae at apex of medullary pyramid
• Papillae lead into minor calyces

Glossary capsule - a structure enclosing an
organ, usually composed of dense connective
tissue cortex - the outer portion of an organ,
distinguished from its inner, medullary
portion septum/septa - a wall, dividing a cavity
or structure into smaller ones calyx plural
noun calyces - a cuplike cavity or
structure minor lesser, small, major -
greater hilus or hilum - a depression or pit at
that part of an organ where the vessels and
nerves enter medulla - the inner portion of an
organ, usually in the center See also
http//www.bu.edu/histology/m/glossary.htm
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on either side of medullary pyramid
Posterior division of
renal artery
Interlobular arteries

• Kidney blood supply
• 0.5 of total body weight, 25 of the cardiac
  output
• renal artery, anterior posterior divisions,
  segmental arteries (do not anastomose, end
  arteries)
• interlobar arteries on either side of medullary
  pyramid
• - arcuate artery (Latin curved) between cortex
  and medulla, parallel to kidney surface),
  interlobular arteries

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juxtamedullary glomerulus
Posterior segment

• interlobular arteries ? afferent arteriole ?
  glomerulus ? efferent arterioles
• efferent arterioles in the cortex form
  peritubular capillary plexus
• - efferent arterioles of juxtamedullary nephrons
  (juxta Latin close to)
• go into medulla and loop back vasa recta
  (straight vessels Latin)

Afferent, from afferre Latin to bring
toward Efferent, from efferre Latin to bring
out

• Correlation with pathology
• - cortex 90 of blood supply
• - medulla is relatively a-vascular (10, low
  oxygenation)
• tubular capillary beds derived from the efferent
  arterioles
• acute tubular necrosis (injury), papillary
  necrosis

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vascular pole
Bc

tubular pole
Glomerulus in paraffin section Bowmans capsule
(Bc) glomerular tuft
Afferent arterioles arise from interlobular
vessels and supply the glomeruli Efferent
arterioles arise from glomerular capillaries
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Questions? mpicken_at_luc.edu