Chapter 26

1. Chapter 26 The Urinary System

2. Three major functions: excretion: elimination: regulate blood plasma: removal of organic wastes from body fluids discharge of waste products into the environment volume and solute concentration

3. Major organs • kidneys (2) • urinary tract: • ureters (2) • urinary bladder (1) • urethra (1) produce urine water, soluble compounds kidney to urinary bladder temporary storage of urine urinary bladder to exterior

4. Other important functions: • regulate blood volume and pressure • regulate [ions] in blood • Na+, K+, Cl-, etc., • stabilize blood pH • conserve nutrients • while getting rid of wastes • detoxify compounds

5. kidney location fig. 26-2 fig. 26-2a

6. The Kidneys • location • on either side of vertebral column • around T12 to L3 • capped by adrenal gland • retroperitoneal • supported by CT • surrounded by adipose (cushioning)

7. to here 4/4/07 lec# 35

8. The Kidneys anatomy: • hilum indentation • entry/exit • ureters • renal artery, vein, nerves

9. fig. 26-4a

10. The Kidneys anatomy: nephrons renal cortex renal medulla renal pyramids minor calyx major calyx renal pelvis tubular functional numerous vascular

11. The Kidneys blood supply 20-25% of cardiac output renal artery segmental artery interlobar artery arcuate artery

12. kidney vasculature fig. 26-5a

13. fig. 26-5a

14. The Kidneys blood supply coming off of arcuate arteries interlobular arteries afferent arteriole glomerulus efferent arteriole peritubular capillary interlobular veins arcuate veins

15. fig. 26-5a

16. The nephron overview renal corpuscle renal tubule renal tubule renal corpuscle fig 26-6

17. Bowman’s capsule proximal convoluted tubule Bowman’s capsule dct pct loop of Henle distal convoluted tubule loop of Henle The nephron: parts fig. 26-6a

18. fig. 26-9

19. The nephron: blood supply efferent arteriole ? glomerulus (capillary bed) afferent arteriole fig. 26-6a

20. The nephron: blood supply peritubular capillaries efferent arteriole glomerulus (capillary bed) afferent arteriole fig. 26-6a

21. The nephron: Bowman’s capsule hollow structure two layers visceral (inner) parietal (outer) surrounds glomerulus fig 26-6a

22. The nephron: Bowman’s capsule fig. 26-8

23. What is between blood and space? podocytes and filtration slits lamina densa (connective tissue) fenestrated endothelium (capillary)

24. podocyte 2 pedicel pedicel podocyte 1 filtration slits

25. The nephron: Bowman’s capsule fig. 26-8

26. blood endothelium lamina densa filtration slits capsular space = filtration membrane fig. 26-10

27. blood pressure forces water and small solutes across “membrane” into Bowman’s capsule fig. 26-10

28. wastes but also water glucose amino acids vitamins fatty acids etc. = glomular filtrate fig. 26-10

29. but not: cells large plasma proteins fig. 26-10

30. proximal convoluted tubule pct The nephron: proximal convoluted tubule fig. 26-6a

31. The nephron: proximal convoluted tubule • cuboidal cells • microvilli • reabsorption • remove water, nutrients etc., from the glomerular filtrate and release them into the peritubular fluid

32. loop of Henle loop of Henle The nephron: loop of Henle fig. 26-6a

33. The nephron: loop of Henle descending limb thick pumps Na+ Cl- out of fluid thin permeable to H2O ascending limb thin thick

34. dct distal convoluted tubule The nephron: distal convoluted tubule fig. 26-6a

35. The nephron: distal convoluted tubule active secretion (ions, acids, drugs) selective reabsorption of Na+ and Ca2+ selective reabsorption of H2O

36. The nephron: distal convoluted tubule also part of the jg apparatus (JGA) (juxtaglomerular) macula densa (DCT) juxtaglomerular cells (afferent arteriole) secrete EPO, renin

37. juxtaglomerular apparatus

38. collecting duct papillary duct minor calyx The collecting system DCT …

39. 100 keys (pg. 959) “The kidneys remove waste products from the blood; they also assist in the regulation of blood volume and blood pressure, ion levels, and blood pH. Nephrons are the primary functional units of the kidneys.”

40. Renal Physiology what is the kidney doing how does it accomplish these tasks Goal regulate volume and composition of the blood involves excretion of wastes

41. Renal Physiology three major organic wastes urea creatinine uric acid 21g / day from amino acid breakdown 1.8 g / day from CP breakdown 480 mg / day recycling RNA N-bases

42. Renal Physiology three major organic wastes can be eliminated only when dissolved in urine (H2O loss) production of hyperosmotic urine restrict excessive H2O loss reabsorb useful molecules

43. Renal Physiology: steps 1. filtration blood pressure forcing water and small solutes (good and bad) from capillaries into capsular space

44. Renal Physiology: steps 2. reabsorption remove water and many solutes from filtrate by: diffusion, osmosis channel-mediated diffusion carrier-mediated transport

45. Renal Physiology: steps 2. reabsorption many different proteins involved a cell may have many functions differential distribution of proteins transport can be saturated

46. Renal Physiology: steps 3. secretion transport of solutes from body fluids into the tubular fluid (or filtrate)

47. table 26-2

48. to here 4/11/07 lec# 36

49. Filtration filtration membrane lets water and small solutes through cells and plasma proteins stay in capillaries

50. 100 keys (pg. 969) “Roughly 180 L of filtrate is produced at the glomeruli each day, and that represents 70 times the total plasma volume. Almost all of that fluid volume must be reabsorbed to avoid fatal dehydration.”