Where does pee come from?

1. Where does pee come from? Rachel Boggus Boggusrl@email.uc.edu

2. The Kidney • Pretty kidney • But of course you need to know more about it than this

4. The kidney in detail • Why does the cortex have a granular appearance? • Why does the medulla have a striated appearance?

5. The kidney in detail • Why does the cortex have a granular appearance? • Because of the presence of renal corpuscles • Why does the medulla have a striated appearance? • Because of the radially oriented tubules that it is composed of.

6. More Kidney fun • In your notes, Dr. Michaels talks about the ureter expanding into the renal pelviscalyx, etc. In the REVERSE order of the flow of urine. I’m presenting it here in the order that urine flows through it. Because I think that makes more sense.

7. More Kidney fun • Formed urine passes through large collecting ducts in the papilla and into the minor calyx

8. Several minor calyxes come together to form a major calyx.

9. The major calyces come together forming the renal pelvis which then forms the ureter

10. So go over the flow of formed urine

11. So go over the flow of formed urine • Formed urine begins in the large collecting ducts in the renal papilla. From there it enters the minor calyces which come together forming the major calyces which come together forming the renal pelvis which constricts forming the ureter.

12. More GROSS kidney • Lobes and lobules • Each lobe has a medullary pyramid (the papilla is at the tip of the pyramid) and a cortex that sits on top of the medullary pyramid • Renal columns (of Bertin, if you will) are cortical tissue that extend beyond the pyramid

13. Dr. Michaels thinks its like an ice cream cone… whatever

14. Lobules • Are cylindrical and have a central core, a medullary ray/pars radiata consisting of radially-oriented tubes • Peripheral to medullary rays are the proximal and distal convoluted tubules (PCT and DCT) in the pars convoluta/cortical labyrinth

15. What is contained in the medullary rays? • What is contained in the pars convoluta?

16. What is contained in the medullary rays? • Descending and ascending thick limbs and collecting ducts • What is contained in the pars convoluta? • Proximal and distal convoluted tubules, the connecting tubules and the renal corpuscles

17. BLOOD SUPPLY • Renal arteryinterlobar arteriesarcuate arteriesinterlobular arteriesafferent arteriolesglomerular capillariesefferent arterioleseither peritubular plexus or vasa recta

18. Interlobar arteries

19. Nephron

20. Proximal end of nephronrenal corpuscle • 2 parts of a renal corpuscle? • Glomerulus and bowman’s capsule • Remember that between the bowman’s capsule and the glomerulus is the bowman’s space – filled with pee

21. The rest of the nephron is tubular • Begins with proximal convoluted tubule (PROXIMAL to the glomerulus) • Extends to medullary ray where it descends toward the medulla as the straight portion of the proximal tubule or descending thick limb

23. Proximal convoluted tubulestraight portion/thick descending limbin the medulla abrupt transition to the thin descending limb

25. Glomerulusproximal convoluted tubulestraight portion of proximal convoluted tubule/thick descending limbthin descending limb • Hairpin loop upwards towards cortex as thin ascending limb

27. Glomerulusproximal convoluted tubulestraight portion of proximal convoluted tubule/thick descending limbthin descending limbthin ascending limb • Straight portion of the distal tubule/thick ascending limb

29. Glomerulusproximal convoluted tubulestraight portion of proximal convoluted tubule/thick descending limbthin descending limbthin ascending limbthick ascending limb/straight portion of the distal tubule • Enters medullary ray, extends to pars convoluta, crosses vascular pole and becomes distal convoluted tubule

31. Glomerulusproximal convoluted tubulestraight portion of proximal convoluted tubule/thick descending limbthin descending limbthin ascending limbthick ascending limb/straight portion of the distal tubule distal convoluted tubule • Connecting tubule (branch of collecting duct) which extend from pars convoluta to medullary ray

33. Collecting ducts descend in medullary ray in cortex all the way through the medulla and the papilla papillary ducts

34. What regions of the nephron are in the pars convoluta? • Renal corpuscle, PCT, DCT, connecting tubule • What regions of the nephron are located in the pars radiata (medullary ray)? • Portions of the straight proximal (descending thick limb) and straight distal tubule (ascending thick limb), part of collecting duct

35. What parts of the nephron are located in the medulla? • Descending thick limb, descending and ascending thin limbs of the loop of Henle, and ascending thick limb • Collecting ducts, papillary ducts

36. Down and dirty with the PCT

37. Simple cuboidal epithelium • Irregular apical surface • Lots of mitochondria acidophilic • Lateral cell membranes not visible • because of interdigitation • 3 segements, s1, s2, s3

38. EMs of proximal and distal convoluted tubules

39. Another EM of a proximal convoluted tubule… note the brush border • Also notice the crap-load of mitochondria

40. What are the functions of the proximal convoluted tubules? • Reabsorption of 60-80% of the glomerular filtrate • Active transport of Na • Removal of virtually all glucose and proteins from provisional urine *** If people are confused, REABSORPTION is from the pee tube into the interstitium, SECRETION is from interstitium to the pee tube ***

41. Straight Portion of Proximal tubule

42. Straight proximal tubule • Mostly segment S3 • When tubule enters medullary ray • Interdigitations less pronounced • Brush border more variable • When epithelium changes to squamousthin descending limb of the loop of henle

43. How do I tell PCT from straight PT? • BECAUSE you are a genius and you know that PCTs are in the cortex in the pars convoluta and that the straight PT is in the medullary ray

44. Thin segment descending and ascending

45. Thin segments • Located in the medulla • Simple squamous epithelium • Lateral interdigitations present

46. Thick Ascending Limbs

47. Blue • Yellowthick descending limbs • Joins thin ascending limb at junction of inner and outer medulla • Also located in the pars radiata/medullary rays

48. Distal Convoluted tubule • When it enters the pars convoluta • Macula densa is adjacent to afferent arteriole (we’ll talk about this later) • No brush border • Has lots of lateral interdigitations • Primary function is reabsorption of ions

49. DCT

50. Macula densa