Urinary System

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Urinary System

• Given by Dr. Attayeb
• Written by Abo Slo7
• Made up 2 date Abo Malek
• Thanks for Dr.Abdullah

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Urinary System

• Consists of -
• Two kidneys
• Two ureters
• Urinary Bladder
• Urethra

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The kidney

• The kidney consists of-
• Outer cortex
• Inner medulla Divided into 10-18 medullar
  pyramids by extensions of the cortex called
  cortical columns ( renal columns )
• Medullar rays are straight extensions from the
  medulla into the cortex.
• 3. Renal pelvis a central branched chamber
  which receives the urine opens into the ureter .

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The uriniferous tubules

• The functional unit of the Kidney is called
  uriniferous tubule which Consists of two parts-
• Nephron
• Collecting duct

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1.The nephron

• The nephron is an epithelial tubule cosisting of
  the following parts-
• Renal corpuscle (in cortex)
• Proximal convulated tubule (in cortex)
• Descending thick limb (in medullary ray)
• Descending thin limb (in medulla)
• Loop of Henle (in medulla)
• Ascending thin limb (in medulla)
• Ascending thick limb (in medullary ray)
• Distal tubule (in cortex)

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2.Collecting tubules

• Cortical collecting tubules (in medullary ray)
• join to form
• Medullary collecting tubules (in the medulla)
• join to form
• Papillary collecting duct of Bellini (in the deep
  part of the medulla called renal papilla)
• Ducts of Bellini open into the renal pelvis .

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Types of nephrons

• Cortical nephrons
• With renal corpuscle in the outer part of the
  cortex short loop of Henle in the medulla.
• Juxta-medullary nephrons
• With renal corpuscle is near the
  cortico-medullary junction long loop of Henle.

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Renal corpuscle

• Contains the glomerulus (fenestrated blood
  capillaries) supplied by afferent arteriole and
  drained by efferent arteriole.
• Surrounding the glomerulus is Bowman's capsule
  witch consists of 2 layers
• Partial layer of simple squamous epithelium.
• Visceral layer of cell called podocytes
  supporting the glomerules.
• Between the two layers is the urinary space

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Components of the glomerulrs

1. Fenestrated capillaries ( fenestration without
   diaphragm )
2. Basal lamina ( filtration barrier )
3. Cell called podocytes.
4. Cell called mesangial cells.

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The podocytes

• The podocytes have primary processes secondary
  cytoplasmic processes. surrounding the basal
  lamina of the glomerular capillaries.
• Between the processes are the filtration slits
  covered with diaphragm.

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Mesangial cells

• Located between the endothelium the basal
  lamina of the glomerular capillaries.
• They are supporting, contractille and phagocytic.

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Proximal convoluted tubule (PCT)

• Sections of PCT are more than those of distal
  tubule because PCT is longer than the distal
  tubule DCT.
• Acidophilic large simple cuboidal cells with
  microvilli (brush border) forming irregular
  lumen.
• Few nuclei appear in section of PCT because the
  cells are larger .
• The descending thick limb is similar to PCT.

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Distal convoluted tubule (DCT)

• Simple cuboidal epithelium.
• Smaller cells and more nuclei in sections than
  PCT.
• Clearly defined lumen without brush border.
• Sections of DCT are less than those of PCT
• The ascending thick limb is similar to PCT

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Juxtaglomerular apparatus

• Found near Bowman's capsule Consists of 3 types
  of cells-
• Juxtaglomerular cells modified smooth muscle
  cells of the afferent arteriole secreting the
  enzyme renin
• Macula densa cells of DCTin contact with
  juxtaglomerular cells without a basal lamina
• Extraglomerular mesangial cells supporting cells
  between the afferent efferent arterioles
  macula densa

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The medulla contains

1. Ascending and descending thin limbs of loop of
   Henle (simple squamous epithelium).
2. The medullary collecting tubules (similar to the
   cortical collecting tubles (simple cuboidal
   epithelium with clear cell boundaries).
3. Papillary collecting ducts of Bellini (tall
   columnar epithelium with clear cell boundaries)
4. Vasa recta descending arterioles and ascending
   venules (simple squamous epithelium).

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The renal pelvis

• The renal pelvis is lined by transitional
  epithelium.
• Has branches called Major and Minor calyces.

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The ureter

• Transitional epithelium.
• In the upper part the muscularis externa has 2
  layers of smooth muscle (inner longitudinal and
  outer circular).
• In the lower part it has 3 layers (inner
  longitudinal and middle circular outer
  longitudinal).
• Adventitia is outer most CT layer.

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Urinary bladder

• Transitional epithelium.
• Lamina propria may contain mucous glands near the
  opening of the urethra .
• Smooth muscle of the muscularis externa forms the
  internal urethral sphincter.
• Adventitia is the outermost CT layer (serosa on
  the superior surface )