The Urinary System

1. The Urinary System Glen Hookey Eric Kolker Justin Loeb Michael Ross Uston—Period 5

2. Overview

3. Animals and Waste • Filter body fluid for toxins and unnecessary substances • Kidneys (bp, activation of vitamin D, erythropoietin, wastes) • Nitrogenous waste

4. Transport Epithelium • Manage solute levels • Line many channels inside the body • Comprised of special epithelial cells • Can move solutes against gradient

5. Nitrogenous Wastes • Three types: Ammonia, Urea, Uric Acid • Ammonia • Highly toxic, diluted with large supplies of water • Urea • Low toxicity, energy cost (used by mammals) • Uric Acid • Low toxicity, water insoluble, excreted as a paste

6. Excretory Processes • Filtration • One layer of transport epithelium (large molecules removed); filtrate • Reabsorption • Active transport (glucose, amino acids, etc.) • Secretion • Materials added to excretory tubule • Excretion • Expelled as urine

7. Filtrate/Urine Pathway

8. Kidney • Filters substances form blood • Adjusts filtrate’s composition • Returns most substances to blood

10. Nephron • Functional unit • Packed tubules • Surrounded by capillaries • Filters blood

11. Bowman’s Capsule • Start of Nephron • Glomerulus • Filtration into lumen: • Water, salts bicarbonate, hydrogen ions, urea, glucose, amino acids

12. Proximal Tubule • pH maintained • Reabsorption • Reabsorbs Na+  osmosis

13. Loop of Henle • Descending • Water • Ascending • Thin & Thick • Passive & Active

14. Distal Tubule • pH regulation • Sodium, calcium, potassium

15. Collecting Duct • Subject to hormonal controls • Diseases • Concentration of filtrate

16. Urine Composition • Excess water and solutes • Ions • Urea • Neurotransmitters • Histamine • Drugs/toxins

17. Osmoregulation • Solute gradient • Bends in nephron • Membrane selective permeability • Diffusion • Active transport • Salt

18. Solute Gradient • Membrane selective permeability • Interstitial fluid • Filtrate • Active transport • Diffusion

19. Nephron Overview Distal Tubule Proximal Tubule Descending Loop of the henle Collecting duct Ascending Loop of the henle

20. Gradient Overview

21. Gradient #1: Proximal tubule • Blood • ~300 mosm/L • Interstitial fluid: • ~300 mosm/L • Filtrate: • ~300 mosm/L • In: • Hydrogen ions • Ammonia • Out: • Bicarbonate • Salt • Water • Nutrients • Potassium ions • In cortex • Volume decreased • Osmolarity stays constant

22. Gradient #2: Descending Loop of the Henle • Interstitial fluid • 300 - 1200 mosm/L • Filtrate • 300 - 1200 mosm/L • In • N/A • Out • Water • Membrane permeable only to water • Salt concentration increases • Water diffuses out

23. Gradient #3: Ascending Loop of the Henle • Ascending loop • Interstitial fluid • 1200 - 300 mosm/L • Filtrate • 1200 - 200 mosm/L • In • N/A • Out • Salt • Membrane permeable only to Salt • Salt concentration decreases • Filtrate osmolarity lowered to increase osmolarity of interstitial fluid

24. Gradient #4: Distal tubule • Interstitial fluid • 300 mosm/L • Filtrate • 100 mosm/L • In • Potassium ions • Hydrogen ions • Out • Salt • Water • Bicarbonate • Filtrate at lowest osmolarity • Key role in determination of pH of urine

25. Gradient #5: Collection duct • Interstitial fluid • 300 - 1200 mosm/L • Filtrate • 300 - 1200 mosm/L • In • N/A • Out • Salt • Urea • Water • Final stage • Controls final salt output • Low salt • Water diffuses • Concentrated filtrate

27. Regulation #1: ADH • Antidiuretic hormone • Hormone • Activated by hypothalamus at high blood osmolarity • Decreases water loss • More permeability to water

28. Regulation #2: RAAS • Renin-angiotensin-aldosterone system • Angiotensin II • Activated at low blood pressure/volume • Decreases water loss • Constricts capillaries • More reabsorption of salt

29. Regulation #3: ANF • Atrial natriuretic factor • Opposite of ADH and RAAS • Triggered by high blood pressure/volume • Inhibits NaCl absorption • Increased water loss through urine • Disables ADH

31. Ureter • Lining of ureter • Smooth-muscle cells contractions • Ureter crosses bladder wall • Ureter in Micturition

32. Urinary Bladder • Storage organ • Bladder in micturition • Brain cells • Structure

33. Urethra • Function and location • Cells of Urethra • External Meatus

34. Abnormalities of the Renal System • Acute • Chronic • Congenital

35. Congenital Problems • Horseshoe kidneys • Functions as one kidney • Has to be cautious of rigorous activity

36. Acute Problems • Usually reversible • Examples: stones, infections, tumors, inflammation, acute renal failure • Detected by urinalysis or by pain and fever

37. Urinary Tract Infection (UTI) • Occurs anywhere along the urinary tract (kidneys, bladder) • Women more prone than men; shorter urethra • Pain and fever • Treated with antibiotics

40. Tumors and Stones • Most tumors in kidneys and bladder are malignant • Smokers are prone to bladder tumors • Stones- intensely painful • Can be passed but some require surgery or ultrasound

43. Trauma • Kidneys damaged by physical trauma • People with one kidney have to avoid potentially dangerous activities • Blood in urine

44. Chronic Kidney Failure • Dialysis (3 days a week; 4 hours) • Cleans blood • Only cure is transplantation