HISTOLOGY OF URINARY
SYSTEM
Dr.GURUDASAN
01.04.13
INTRODUCTION
 The urinary system
consists of
 Kidneys
 Ureters
 Urinary bladder
 Urethra
MAIN FUNCTIONS OF URINARY SYSTEM
 Kidneys filter
Toxins
Metabolic wastes
Excess water
Excess ions
 Disposes nitrogen...
MACROSCOPIC FEATURES
 Kidney has two
regions
Cortex: It lies just
beneath the
connective tissue
capsule.
The cortex ext...
 Some of the striated
patterns from the base of
the pyramid may extend
into the cortex, which are
called as Medullary ray...
GENERAL STRUCTURE OF NEPHRON
 It is the functional unit of
kidney.
 Parts:
 Renal corpuscle
 Proximal convoluted
tubul...
 Renal corpuscle:
- The blind end of each
nephron is expanded in
the cortical region into a
double walled cup called
Bowm...
 Glomerulus is the tuft of
capillaries fed by
afferent arteriole and
drained by efferent
arteriole (vascular pole).
 Aff...
 Glomerulus has
fenestrated endothelium.
 Mesangial cells –
specialised supporting
connective tissue cells in
capillary ...
 PODOCYTES:
 These are cells of visceral
layer of renal corpuscles
that envelope glomerular
capillaries.
 They have lon...
JUXTAGLOMERULAR APPARATUS
 JUXTAGLOMERULAR CELLS:
- Modified smooth muscle cells
present in Tunica media of afferent
arte...
COMPONENTS OF GLOMERULAR FILTER
 During filtration, the
glomerular filtrate passes
through three layers.
I) Fenestrated e...
PROXIMAL CONVOLUTED TUBULE
 Confined to renal cortex
 Cuboidal epithelial cells
with long microvilli (fuzzy
appearance)
...
LOOP OF HENLE
 Arises from PCT in cortex,
dips down into medulla
as descending limb and
loops back as ascending
limb and ...
DISTAL CONVOLUTED TUBULE
 Confined to the renal
cortex
 Simple cuboidal
epithelium
 Selective secretion and
resorption ...
DIFFERENCES BETWEEN PCT AND DCT
 DIAMETER: It is more
(about 45 – 60µm)
 Lining cells are pyramidal
and broad
 Has brus...
PROXIMAL CONVOLUTED
TUBULE
DISTAL
CONVOLUTED TUBULE
COLLECTING DUCT
 It begins in the medullary
ray as the continuation of
DCT.
 As it enters medulla it is
joined by severa...
THE URETERS
 Slender tubes about 25
cm (10 “) long leaving
each renal pelvis
 One for each kidney
carrying urine to the
...
Three basic layers
 Mucosa:Transitional
epithelium of mucosa
stretches when
ureters fill
 Muscle layer:
Inner longitudi...
 Collapsible muscular sac
 Stores and expels urine
 Lies on pelvic floor
posterior to pubic
symphysis
 Males: anterior...
Bladder wall has three
layers (same as ureters)
Mucosa with
distensible transitional
epithelium and lamnia
propria (can s...
CLINICAL ASPECTS
 Glomerulonephritis:
In DM, degenerative
changes in glomeruli leads
to thickening of
glomerular basement...
 RENAL CALCULI:
- Calcium salts and uric acid
are excreted in
glomerular filtrate. These
salts are less soluble in
water ...
THANK YOU
Histology of urinary system
Histology of urinary system
Histology of urinary system
Histology of urinary system
Histology of urinary system
Histology of urinary system
Histology of urinary system
Histology of urinary system
Histology of urinary system
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Histology of urinary system

  1. 1. HISTOLOGY OF URINARY SYSTEM Dr.GURUDASAN 01.04.13
  2. 2. INTRODUCTION  The urinary system consists of  Kidneys  Ureters  Urinary bladder  Urethra
  3. 3. MAIN FUNCTIONS OF URINARY SYSTEM  Kidneys filter Toxins Metabolic wastes Excess water Excess ions  Disposes nitrogenous wastes from blood Urea Uric acid Creatinine  Regulate the balance of water and electrolytes, acids and bases.
  4. 4. MACROSCOPIC FEATURES  Kidney has two regions Cortex: It lies just beneath the connective tissue capsule. The cortex extends at the margins between each pyramid as Renal columns.
  5. 5.  Some of the striated patterns from the base of the pyramid may extend into the cortex, which are called as Medullary rays.  KIDNEY LOBE:  It is defined as a renal pyramid with its overlying cortex and laterally associated renal columns. LOBULE OF KIDNEY – IT IS DEFINED AS MEDULLARY RAY WITH ITS LATERALLY ASSOCIATED CORTICAL TISSUE.
  6. 6. GENERAL STRUCTURE OF NEPHRON  It is the functional unit of kidney.  Parts:  Renal corpuscle  Proximal convoluted tubule  Loop of Henle  Distal convoluted tubule  Collecting duct
  7. 7.  Renal corpuscle: - The blind end of each nephron is expanded in the cortical region into a double walled cup called Bowman’s capsule. - It consists of outer parietal layer (Simple squamous) - Inner visceral layer(specialised epithelial cells – podocytes) - Bowman’s space – space between parietal and visceral layer
  8. 8.  Glomerulus is the tuft of capillaries fed by afferent arteriole and drained by efferent arteriole (vascular pole).  Afferent arteriole – Large  Efferent arteriole – small  Varying diameters of arterioles facilitate active filtration due to pressure gradient.
  9. 9.  Glomerulus has fenestrated endothelium.  Mesangial cells – specialised supporting connective tissue cells in capillary network. These are satellite cells with contractil eand phagocytic property.  Their phagocytic property helps to remove large proteins and filtration residues.  The glomerular capillaries are closely invested by podocytes.
  10. 10.  PODOCYTES:  These are cells of visceral layer of renal corpuscles that envelope glomerular capillaries.  They have long cytoplasmic processes called primary processes, which in turn gives rise to short secondary foot processes or pedicles.  The secondary processes interdigitate with adjacent podocytes and form elongated gaps called filtration slits/pores.
  11. 11. JUXTAGLOMERULAR APPARATUS  JUXTAGLOMERULAR CELLS: - Modified smooth muscle cells present in Tunica media of afferent arteriole. - Sensitive to pressure of blood in the afferent arteriole. - Secretes renin MACULA DENSA: - Specialised region in the wall of DCT which comes in contact with JG cells. - Cells are taller and their nuclei are denser and close to one another. - Sensitive to concentration of sodium ions in the fluid present in DCT. LACIS (NETWORK) CELLS: Extra glomerular mesangial cells found at the vascular pole of the renal corpuscle. - May be involved in production of erythropoietin.
  12. 12. COMPONENTS OF GLOMERULAR FILTER  During filtration, the glomerular filtrate passes through three layers. I) Fenestrated endothelium of glomerular capillary – Acts as coarse filter preventing cellular elemets and allowing only plasma. II) Glomerular basement membrane – It is a selective macromolecular filter preventing passage of particles greater than 10 nm in diameter. III) Filtration slits This makes glomerular filtrate similar to plasma wihout plasma proteins(macromolecule). GFR – 125 ml/min. 124 ml is reabsorbed in renal tubules, 1 ml is released as urine
  13. 13. PROXIMAL CONVOLUTED TUBULE  Confined to renal cortex  Cuboidal epithelial cells with long microvilli (fuzzy appearance)  Resorption of water, ions and solutes
  14. 14. LOOP OF HENLE  Arises from PCT in cortex, dips down into medulla as descending limb and loops back as ascending limb and continuous with DCT at the cortico- medullary junction.  Thin segment – Simple squamous epithelium (permeable to water and sodium)  Thick ascending limb cuboidal epithelium ( impermeable to water)
  15. 15. DISTAL CONVOLUTED TUBULE  Confined to the renal cortex  Simple cuboidal epithelium  Selective secretion and resorption of ions – This is coupled with secretion of Hydrogen and potassium ions ( one hydrogen or potassium ion is secreted for every sodium ion reabsorbed) – this is controlled by aldosterone.  DCT is involved in maintenance of acid-base balance.
  16. 16. DIFFERENCES BETWEEN PCT AND DCT  DIAMETER: It is more (about 45 – 60µm)  Lining cells are pyramidal and broad  Has brush border  Lumen of tubule is irregular and star shaped  Cytoplasm is darkly stained with Eosin and cell outlines are not clear.  Nuclei are large, spherical and basally or centrally placed.  DIAMETER: It is less ( About 25 – 50 µm)  Lining cells are cuboidal  Has no brush border  Lumen of tubule is large and regular  Cytoplasm is lightly stained with Eosin and cell outlines are clear.  Nuclei are small, spherical and located more in apex. PROXIMAL CONVOLUTED TUBULE DISTAL CONVOLUTED TUBULE
  17. 17. PROXIMAL CONVOLUTED TUBULE DISTAL CONVOLUTED TUBULE
  18. 18. COLLECTING DUCT  It begins in the medullary ray as the continuation of DCT.  As it enters medulla it is joined by several other collecting tubules to form larger ducts (Ducts of Belini).  These are lined by simple cuboidal epithelium with distinct cell boundaries and clear pale cytoplasm.  Normally not permeable to water, but in the presence of ADH it becomes permeable
  19. 19. THE URETERS  Slender tubes about 25 cm (10 “) long leaving each renal pelvis  One for each kidney carrying urine to the bladder  Descend retroperitonealy and cross pelvic brim  Enter posterolateral corners of bladder  Run medially within posterior bladder wall before opening into interior  This oblique entry helps prevent backflow of urine
  20. 20. Three basic layers  Mucosa:Transitional epithelium of mucosa stretches when ureters fill  Muscle layer: Inner longitudinal, outer circular layers Inferior 3rd with extra longitudinal layer) Stimulated to contract when urine in ureter: peristaltic waves to propel urine to bladder  Adventitia (external)– Loose conn. Tissue with blood vessels, lymphatics and nerves
  21. 21.  Collapsible muscular sac  Stores and expels urine  Lies on pelvic floor posterior to pubic symphysis  Males: anterior to rectum  Females: just anterior to the vagina and uterus URINARY BLADDER
  22. 22. Bladder wall has three layers (same as ureters) Mucosa with distensible transitional epithelium and lamnia propria (can stretch) Thick muscularis called the detrusor muscle  3 layers of highly intermingled smooth muscle  Squeezes urine out Fibrous adventitia
  23. 23. CLINICAL ASPECTS  Glomerulonephritis: In DM, degenerative changes in glomeruli leads to thickening of glomerular basement membrane and damage to the podocytes and alteration of slit pore membrane. As a result glomerular filter becomes more permeable to proteins and subsequent release of proteins in urine (proteinuria)
  24. 24.  RENAL CALCULI: - Calcium salts and uric acid are excreted in glomerular filtrate. These salts are less soluble in water and later crystallize to form stones
  25. 25. THANK YOU
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