1. Urinary System Ji-Cheng Li

2. 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

3. 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

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

6. *renal lobe: one renal pyramid and its bounding cortical tissue
*renal lobule: renal tissue including one medullary ray and ½ cortical tissue surround it

7. According to function, renal parenchyma is mainly consists of uriniferous tubules
/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

8. juxtamedullary nephron /renal glomerulus: /renal capsule
structural and functional unit,
1,000,000
---renal corpuscle:
cortical nephron
juxtamedullary nephron
/renal glomerulus:
/renal capsule

9. ---renal tubule:
/proximal tubule:
-convoluted portion
-straight portion
/thin segment
/distal tubule:

10. ①  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, nm, no diaphragm
/basal lamina: 330nm

11. *intraglomerular mesangium:
/mesangial cell:

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

13. ---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

14. *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

15. ---function: produce filtrate by filtration

16. filtration barrier:
fenestrated endothelial cell: negative ions
basal lamina
slit membrane

18. ②   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)

20. Proximal tubule

21. ---Function:
i. reabsorption :
-85% Na+ ions and water
-All of glucose, aminoacid, polypeptide, proteins and vitamin
ii. secrete H+, NH3, hippuric acid and creatinine

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

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

24. Distal tubule
Plasma membrane infolding

25. ---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)

26. medullary loop (nephron loop )
proximal tubule ,
thin segment,
distal tubule

27. 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

28. 4)    juxtaglomerular complex

29. 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

31. 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

32. 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

33. 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

34. 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

35. Interlobar arteries → Arcuate arteries →Interlobular arteries →Capsular cap.
↑ ↓ ↓
Renal artery Afferent arterioles Afferent arterioles
↓ ↓
Juxtamedullary nephron Cortical nephron
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

36. Thanks!