Urinary System

1. Urinary System

2. Contents 1 kidney 2 ureter and urinary bladder 3 key points

3. kidney cortex， medulla， hilum， renal pelvis， pyramid， medullary ray， renal column，major (minor) calyx, cortical labyrinth

4. General structure of kidney capsule kidney cortex parenchyma medulla

5. Medulla Cortex cortex medulla

6. glomerulus renal corpuscle nephron renal capsule (Bowman’s capsule) Proximal convoluted tubule Proximal tubule renal tubule Proximal straight tubule Thin segment Distal convoluted tubule Distal tubule Distal straight tubule uriniferous tubule Arched collecting tubule Collecting tubule Cortical collecting tubule Medullary collecting tubule

7. 1. nephron Definition: It is the structural and functional unit of kidney. It consists of renal corpuscle and renal tubule. Function: producing urine. Classification: cortical nephron juxtamedullary nephron

8. Cortical nephron Juxtamedullary nephron

9. Composition of nephron glomerulus renal corpuscle nephron renal capsule (Bowman’s capsule) Proximal convoluted tubule Proximal tubule renal tubule Proximal straight tubule Thin segment Distal convoluted tubule Distal tubule Distal straight tubule

10. 1) renal corpuscle Consisting of renal capsule (bowman’s capsule)and glomerulus. Each renal corpuscle has one vascular pole and one urinary pole.

11. (1) glomerulus A tuft of arterial capillary, belongs to fenestrated capillary, Mesansium can be found between capillaries. Mesansium is composed of mesangial cells and matrix phagocytosis； Secretion of IL-1,etc； Contraction； Structural support Mesangial cell

13. (2) renal capsule Formation: the blind end of renal tubule invaginates and surrounds the glomerulus. Parietal layer: Made up of Simple squmous epithelium Visceral layer: Made up of podocytes Renal capsule

15. podocyte large cell with many processes (primary processes and secondary processes) filtration slits between secondary processes is covered by filtration slit membrane.

16. (3) Filtration membrane Fenestrated endothelium Basement lamina Filtration slit membrane Filtration membrane

17. Fenestrated endothelial cell Secondary process primary process cell body of podocyte

18. Primary process Secondary (foot) process Filtration slit membrane Basement lamina Endothelium Filtration membrane

19. 2) Renal tubule Proximal convoluted tubule Proximal tubule renal tubule Proximal straight tubule Loop of Henle Thin segment Distal straight tubule Distal tubule Distal convoluted tubule

20. (1) proximal convoluted tubule(PCT) Its lumen is irregular. LM: PCT is lined with simple epithelium. Cell are large，cuboidal or cone in shape and stained intensely. The boundary between adjacent cells is obscure, with brush border on the free surface and basal striations on the basal surface. EM: Lateral 相邻细胞有侧突相嵌合， Microvilli on the free surface; Basal interdigitations on the basal surface. Function：main site for reabsorption of glomerular filtrate. secretion and excretion：Ｈ＋、NH4＋

22. Microvilli and basal interdigitation

23. Basal interdigitation

24. (2) thin segment Its wall is made up of simple squamous epithelium. Without brush border H2O and ions are easier to transmit.

25. (3) distal convoluted tubuleDCT DCT：with regular ,larger lumen. LM: PCT is lined with simple cuboidal epithelium. Cells are small and stained intensely. The boundary between adjacent cells is clear, without brush border on the free surface, with obvious basal striations on the basal surface EM: short microvilli on free surface. basal interdigitations are more developed. Function：main site for ions exchange.

26. Distal convoluted tubule

27. Distal convoluted tubule

28. Renal tubules

29. 2 collecting tubule Arched collecting tubule Collecting tubule Cortical collecting tubule Medullary collecting tubule Function：further reabsorption of H2O and exchange of ions, making urine more concentrated. 1~2L/h glomerular filtrate

30. Collecting tubule

31. Collecting tubule

32. 3. juxtaglomerular complex It consists of juxtaglomerular cell, macula densa, extraglomerular mesangial celland peripolar cell at vascular pole.

33. 1) juxtaglomerular cell It is the modified smooth muscle fiber in the tunica media of afferent arteriole at vascular pole. Function： producing renin. angiotensinogen-------angiotensinⅠ--------angiotensinⅡ secreting erythropoietin ACE

34. 2) macula densa • Epithelial cells of DCT become taller and narrower and • arranged compactly near juxtaglomerular cells. • Function：sensing the concentration change of Na+ ion in distal tubules. • macula densa • [Na+ ]in distal tubule-------- juxtaglomerular cell secreting renin-- • -- reabsorption of Na+ in distal tubule and collecting tubule--- blood [Na+ ]

35. 3) extraglomerular mesangial cell In the triangle area between afferent and efferent arterioles, similar to intraglomerular mesangial cells and continuous with them. Function: similar to that of intraglomerular mesangial cells. 4) peripolar cell at the site where visceral layer and parietal layer of renal capsule joint.

37. juxtaglomerular complex

38. glomerulus renal corpuscle nephron renal capsule (Bowman’s capsule) Proximal convoluted tubule Proximal tubule renal tubule Proximal straight tubule Thin segment Distal convoluted tubule Distal tubule Distal straight tubule uriniferous tubule Arched collecting tubule Collecting tubule Cortical collecting tubule Medullary collecting tubule

39. Ureter and urinary bladder They both have 3 layers:mucosa,muscle layer and adventitia. Their luminal surfaces are covered by transitional epithelium.

40. Key points 1 the structure of nephron 2 the structure of PCT and DCT under LM and EM 3 the composition of juxtaglomerular complex and their functions 4 the type of epithelium covering the luminal surface of ureter and urinary bladder