Urinary System Ji-Cheng Li

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Urinary SystemJi-Cheng Li
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• Components
• ---kidney produce urine
• ---ureters
• ---bladder -cavity organs, conduct, store
  and
• ---urethra remove the urine
• ---functions
• remove waste products of metabolism
• regulate the homeostasis
• secrete some bioactive factors - renin,
  erythropoietin

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2. Kidney

• ---hilum BV, LV, N and ureters enter or out
• renal pelvis funnel-shaped expension of upper
  end of ureter
• calyx branches of renal pelvis

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• 1)   General structure
• ---capsule DCT
• ---cortex
• /medullary ray
• /cortical labyrinth
• /renal columns
• ---medulla
• /renal pyramid
• /renal papillae
• -minor calyx
• -major calyx
• -pelvis

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• renal lobe one renal pyramid and its bounding
  cortical tissue
• renal lobule renal tissue including one
  medullary ray and ½ cortical tissue surround it

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• According to function, renal parenchyma
  is mainly consists of uriniferous tubules
• ---parenchyma
• /uriniferous tubules renal tubule collecting
  tubules
• /renal corpuscle glomerulus renal capsule
  (beginning part of renal tubule)
• /nephron renal corpuscle renal tubule
• ---interstitium CT, BV, N

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• 2) Nephron
• structural and functional unit,
• 1,000,000
• ---renal corpuscle
• cortical nephron
• juxtamedullary nephron
• /renal glomerulus
• /renal capsule

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• ---renal tubule
• /proximal tubule
• -convoluted portion
• -straight portion
• /thin segment
• /distal tubule
• -straight portion
• -convoluted portion

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• ?  renal corpuscle spherical, 200um in D,
  two poles vascular pole and urinary pole
• ---glomerulus afferent arterioles?capillary
  network ?efferent arterioles
• capillary network
• /endothelial cell pore, 70-90 nm, no
  diaphragm
• /basal lamina 330nm

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• intraglomerular mesangium
• /mesangial cell

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• -functions
• i.   produce ground substance
• ii.  phagocytosis
• iii. contract
• iv. secrete renin and enzymes

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• ---renal capsule two layers capsule formed by
  beginning part of renal tubule which is enlarged
  and invaginated
• /parietal layer simple squamous epi.
• /visceral layer podocytes
• /renel capsular cavity the space between
  two layers

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podocyte

• cells with many processes
• (primary and secondary processes-foot
  processes)
• Foot processes interdigitated with each other
  and embraced the capillaries,
• slit pore
• -narrow intercellular space between foot
  processes
• -25 nm, with 4-6 nm diaphragm-slit membrane

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---function produce filtrate by filtration
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• filtration barrier
• fenestrated endothelial cell negative ions
• basal lamina
• slit membrane

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• ?   renal tubule
• a. proximal tubule 50-60um in D, 14 mm long
• ---structure
• LM
  EM
• pyramidal cuboidal
• eosinophilic
• round N
• brush-liked border - microvilli
• longitudinal striation- plasma membrane infolding
• no clear boundary - lateral extension
• (rich in
  Na K ATPase)

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Proximal tubule
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• ---Function
• i. reabsorption
• -85 Na ions and water
• -All of glucose, aminoacid, polypeptide,
  proteins and vitamin
• ii. secrete H, NH3, hippuric acid and creatinine

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• b. thin segment
• /10-15 um, simple squamous epi,
• /facilitate the passage of water and ions
• /reabsorb Na and Cl- and 5 water

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• c. distal tubule
• ---structure
• LM
  EM
• cuboidal
• slight-stained
• round N
• no brush-liked border less microvilli
• well-developed
• longitudinal striation plasma membrane
  infolding

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Distal tubule
Plasma membrane infolding
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• ---function
• i.    reabsorption of 8 water, Na ions
• ii.   excretion of K, H,NH3
• iii. regulated by aldosterone (adrenal gland)
  and antidiuretic hormone (vasopressin) (pituitary
  gland)

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medullary loop (nephron loop )

• proximal tubule ,
• thin segment,
• distal tubule

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• 3) collecting tubule
• arched collecting tubules
• cortical collection tubules
• medullary collection tubules
• -simple cuboidal epi. to simple columnar epi.
• -slight stained
• -have clear boundary
• -reabsorb 4 water

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• 4)    juxtaglomerular complex

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• a. juxtaglomerular cell
• ---a groups of modified SM cell of afferent
  arterioles
• ---structure
• -larger, cuboidal in shaped, with round N
• -contain secretory granules
• ---function
• i.secrete renin?adrenal gland?aldosterone?blood
  pressure?
• 
  ?
• angiotensinogen?angiotensin I?angiotensin
  II?contraction of
• 
  SM of BV
• ii. secrete erythropoietin to promote
  erythropoiesis

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• b. macula densa
• ---a group of cells derived from epi. of distal
  tubule
• ---cell becomes taller, narrow, with round N
  apical part arranged
• ---cells have processes connecting with other
  cells
• ---function chemoreceptors- feel the Na ions
  concentration

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• c. extraglomerular mesangial cell (polar cushion
  cell)
• ---similar to intraglomerular mesangial cell
• ---transfer the information
• d. peripolar cell
• ---structure
• EM -microvilli
• -junctional complexes
• -RER, Golgi, and granules
• ---function regulate the reabsorption and
  secretion of renal tubule

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• 5) renal interstitial CT
• ---fibers type I,III,IV collagen
• ---matrix
• ---cell
• fibroblast
• macrophage
• lipid-laden interstitial cell
• -stellate cell with processes
• -osmiophilic lipid droplets
• -function
• i.   involve in formation of F and
  matrix
• ii.  secret prostaglandin

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• 6) Blood supply to the kidney
• i. Very large blood flow (1.2L/min)
• ii. To form cap.two times
• iii. Glomerular cap. have a high blood pressure
• iv. Form vasa recta loop near medullary loop
• v. More larger blood flow in renal cortex

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• Interlobar arteries ? Arcuate arteries
  ?Interlobular arteries ?Capsular cap.
• ?
  ?
  ?
• Renal artery
  Afferent arterioles Afferent arterioles
• 
  ?
  ?
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  Juxtamedullary nephron Cortical nephron
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  glomerulus
  glomerulus
• 
  ?
  ?
• 
  Efferent arterioles Efferent
  arterioles
• 
  ?
  ?
• Vasa recta(artery and vein)?
  Capillary network Capillary network
• 
  ? ?
  ?
• Renal vein?Interlobar vein? Arcuate vein ?
  Interlobular vein ? Stellate vein
• 
  
  
  

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Thanks!