1. Copyright 2010, John Wiley & Sons, Inc. Chapter 21 The Urinary System

2. Copyright 2010, John Wiley & Sons, Inc. End of Chapter 21 Copyright 2010 John Wiley & Sons, Inc. All rights reserved. Reproduction or translation of this work beyond that permitted in section 117 of the 1976 United States Copyright Act without express permission of the copyright owner is unlawful. Request for further information should be addressed to the Permission Department, John Wiley & Sons, Inc. The purchaser may make back-up copies for his/her own use only and not for distribution or resale. The Publishers assumes no responsibility for errors, omissions, or damages caused by the use of theses programs or from the use of the information herein.

3. Copyright 2010, John Wiley & Sons, Inc. Urinary System Two kidneys and two ureters Urinary bladder & urethra Effector organ for 1.Regulation of Plasma ion composition 2.Regulation of Body water Volume (BP) 3.Regulation of blood pH (with lung) 4.Production of Hormones 5.Excretion of waste

4. Copyright 2010, John Wiley & Sons, Inc. Urinary System

5. Copyright 2010, John Wiley & Sons, Inc. Kidney Divided into cortex –outer portion Medulla- inner portion  Contain renal pyramids & renal columns Urine goes into renal pelvis  Edges are made of major & minor calyces Then out ureter

6. Copyright 2010, John Wiley & Sons, Inc. Kidney

7. Copyright 2010, John Wiley & Sons, Inc. Renal Blood Supply 20-25% resting CO goes through kidneys  L. & R. renal arteries then  Segmental  interlobar  arcuate  interlobular  afferent arterioles  glomerulus (capillary network)  efferent arterioles  peritubular capillaries  veins    renal vein Capillaris Units –nephrons grouped at pyramids

8. Copyright 2010, John Wiley & Sons, Inc. Renal Blood Supply

9. Copyright 2010, John Wiley & Sons, Inc. Renal Blood Supply

10. Copyright 2010, John Wiley & Sons, Inc. Nephron Unit of renal function: corpuscle & tubule Corpuscle: forms filtrate Glomerulus & Glomerular capsule (cortex) Proximal convoluted tubule (cortex)  Descending Loop of Henle (into medulla)  ascending Loop of Henle (into medulla)  Distal convoluted tubule (cortex)  Collecting duct  minor calyx

11. Copyright 2010, John Wiley & Sons, Inc. Nephron

12. Copyright 2010, John Wiley & Sons, Inc. Basic Operation Glomerular filtration-filter plasma Tubular reabsorption  Reabsorb needed compounds & water from filtrate Tubular Secretion  Secrete some materials into filtrate Let rest go out as a solution called urine–see Table 21.1

13. Copyright 2010, John Wiley & Sons, Inc. Basic Operation

14. Copyright 2010, John Wiley & Sons, Inc. Glomerular Filtration Two layers of capsule surround glomerulus Between is capsular space Podocytes support capillary epithelium Form filtration membrane Permeable to water & solute but not most proteins & blood cells

15. Copyright 2010, John Wiley & Sons, Inc. Filtration Pressure Blood pressure for filtration Opposed by colloid osmotic pressure and capsular pressure Efferent and afferent arteriole diameters adjust to maintain a net filtration pressure  Even with small changes in blood pressure

16. Copyright 2010, John Wiley & Sons, Inc. Glomerular Filtration Rate = GFR 105-125 ml/min Determines net reabsorption because it determines filtrate flow ANP increases GFR  Responds to increased blood volume Sympathetic stimulation  vasoconstriction  decreased GFR  Urine production

17. Copyright 2010, John Wiley & Sons, Inc. Glomerular Filtration

18. Copyright 2010, John Wiley & Sons, Inc. Tubular Reabsorption Proximal tubule  ~65% Na + & H 2 O  Normally 100% nutrients  ~100% HCO 3 - (depends on blood pH) Active transport of solutes Osmosis moves water Cells distal to proximal tubule fine tune reabsorption under control

19. Copyright 2010, John Wiley & Sons, Inc. Tubular Secretion Takes place all along tubule Major substances : H +, K +, ammonia, urea, creatine, drugs like penicillin Helps regulate plasma pH 7.35-7.45 Diet is acid  urine is typically acidic

20. Copyright 2010, John Wiley & Sons, Inc. Urine Route Collecting ducts to calyces Calyces to ureter Ureter to bladder Bladder to urethra

21. Copyright 2010, John Wiley & Sons, Inc. Filtration, Reabsorption, Secretion

22. Copyright 2010, John Wiley & Sons, Inc. Hormonal Regulation Angiotensin II & aldosterone  Angiotensin II- stimulates NaCl in proximal tube  Aldosterone- increases Na + reabsorption & K + secretion in DCT & CD  More ions reabsorbed  more water ANP-increases GFR & inhibits aldosterone action  less Na + reabsorbed ADH- responds to increased concentration of solute in blood + fall in BP 

23. Copyright 2010, John Wiley & Sons, Inc. Hormonal Regulation ADH: important to body water balance Increased concentration of solute in blood + fall in BP   ADH With no ADH: DCT & CD walls are impermeable to water  dilute urine With ADH: water reabsorption occurs  concentrated urine

24. Copyright 2010, John Wiley & Sons, Inc. Components of Urine Urine = 1-2 l /day 95% water + urea, creatine, K +, ammonia, uric acid, Na +, Cl -, Mg 2+, sulfate, phosphate & Ca 2+ Depends on diet and state of health  See table 21.3

25. Copyright 2010, John Wiley & Sons, Inc. Regulation of Water Reabsorption

26. Copyright 2010, John Wiley & Sons, Inc. Urine Route Collecting ducts  calyces  Ureter  Lined with mucus & transitional epithelium  Pass under bladder  Full bladder prevents backflow  Bladder- directly in front of rectum  Can stretch (700-800 ml)  Smaller in females because of uterus  Three layers of detrussor muscle  Urethra- internal urethral sphincter External urethral sphincter (voluntary)

27. Copyright 2010, John Wiley & Sons, Inc. Urine Route

28. Copyright 2010, John Wiley & Sons, Inc. Micturition = Urination Autonomic reflex- internal sphincter  Responds to stretch like rectum Parasympathetic  detrusor muscle contraction Conscious control-external sphincter

29. Copyright 2010, John Wiley & Sons, Inc. Aging Kidneys shrink- decrease in capacity Thirst decreases  dehydration  urinary tract infections Males: prostate enlargement  frequent urination & slow flow Females: more prone to leakage of external sphincter (incontinence) Both: nocturia