HUMAN RENAL PHYSIOLOGY: FLUID & ELECTROLYTE BALANCE

1. HUMAN RENAL PHYSIOLOGY: FLUID & ELECTROLYTE BALANCE BIOLOGY 305 LABORATORY

2. ANNOUNCEMENTS • Lab Report 2: • Due in lab next week • Don’t forget TurnItIn.com receipt • NO LATE LAB REPORTS ACCEPTED (NO EXCEPTIONS) • Next Week = Last Lab! • Please try not to eat anything 1 – 2 hrs before lab • Final Exam: • Friday May 5th • LH 7 from noon – 2pm • NO MAKEUPs

3. THIS WEEK’S EXERCISE • Acid – Base Reactions: CO2 + H2OH2CO3H+ + HCO3- • Objectives: • Model respiratory/metabolic disturbances • See how changes in PCO2 & addition/removal of acid effect other parameters • Understand forms of CO2 carried in blood • Understand two buffers systems & how they work • Law of Mass Action CA H+ +Pr -

4. THIS WEEK’S EXERCISE • Dissociation Curves: • Understand shape of curve • % Hb-O2 Saturation as function of PO2 • Understand how % Hb-O2 saturation changes as function of PCO2, pH, temperature, etc.. • Understand dual role CO2 plays in Hb-O2 saturation

5. NEXT WEEK: HUMAN RENAL PHYSIOLOGY • Osmoregulators: • Most Terrestrial Vertebrates • Humans maintain fluid composition and concentration irrespective of surrounding environment

6. HUMAN RENAL PHYSIOLOGY • Renal Anatomy • The Nephron: • Bowman's Capsule • PCT • Loop of Henley • DCT • Collecting duct

7. HUMAN RENAL PHYSIOLOGY Bowman’s capsule + glomerular capillaries = glomerulus

8. HUMAN RENAL PHYSIOLOGY

9. HUMAN RENAL PHYSIOLOGY • Functions of the Human Kidney: • Extracellular fluid volume • Regulation of osmolarity • Maintenance of ion balance • Regulation of pH • Excretion of wastes & foreign substances • Production of hormones

10. HUMAN RENAL PHYSIOLOGY • Four Main Processes: • Filtration • Reabsorbtion • Secretion • Excretion

11. HUMAN RENAL PHYSIOLOGY • Functions of the Kidney: • Filtration: • First step in urine formation • Bulk transport of fluid from blood to kidney tubule • Isosmotic filtrate • Blood cells and proteins don’t filter • Result of hydraulic pressure • GFR = 180 L/day

12. HUMAN RENAL PHYSIOLOGY • Functions of the Kidney: • Reabsorbtion: • Process of returning filtered material to bloodstream • 99% of what is filtered • May involve transport protein(s) • Normally glucose is totally reabsorbed

13. HUMAN RENAL PHYSIOLOGY • Functions of the Kidney: • Secretion: • Material added to lumen of kidney from blood • Active transport (usually) of toxins and foreign substances • Saccharine • Penicillin

14. HUMAN RENAL PHYSIOLOGY • Functions of the Kidney: • Excretion: • Loss of fluid from body in form of urine Amount = Amount + Amount -- Amount of Solute Filtered Secreted Reabsorbed Excreted

15. HUMAN RENAL PHYSIOLOGY • Sources of Water Input: • Food & drink: • 2 L/day • Cellular respiration: • Glucose + O2 CO2 + H2O • 0.3 L/day

16. HUMAN RENAL PHYSIOLOGY • Sources of Output: • Urine (1.5 L/day) • Fecal matter (100 mL/day) • Evaporative loss through skin & respiration (900 mL/day)

17. HUMAN RENAL PHYSIOLOGY • Conservation of Water: • Terrestrial animals often face dehydration • Of all sources of water loss, excreted water (in urine) is the most regulated

18. HUMAN RENAL PHYSIOLOGY • Regulation of Fluid Volume: • Kidneys influence fluid volume by: • Altering water content of urine: • Removal of H2O in urine = diuresis • Substances that cause diuresis = diuretics

19. HUMAN RENAL PHYSIOLOGY • Retention of Water is controlled by ADH: • Anti Diuretic Hormone • ADH Release Is Controlled By: • Decrease in Blood Volume • Decrease in Blood Pressure • Increase in ECF Osmolarity

20. HUMAN RENAL PHYSIOLOGY • When Body Fluid Osmolarity Increases (280+): • Osmoreceptors (hypothalamus) • Trigger release of ADH • Increased permeability of CD to water • Water reabsorbion from tubule • Concentrated urine produced

21. HUMAN RENAL PHYSIOLOGY • Regulation of Sodium: • On average, an adult takes in 9 g/NaCl/day • Addition of salt can raise body fluid osmolarity

22. HUMAN RENAL PHYSIOLOGY • Sodium Balance Is Controlled By Aldosterone • Aldosterone: • Steroid hormone • Synthesized in Adrenal Cortex • Causes reabsorbtion of Na+ in DCT & CD • Also, K+ secretion

23. HUMAN RENAL PHYSIOLOGY • Sodium Balance Is Controlled By Aldosterone: • Aldosterone Release: • Triggered by increased ECF K+  Na+ reabsorbtion • Inhibition of Aldosterone: • Triggered by increased extracellular osmolarity No Na+ reabsorbtion

24. HUMAN RENAL PHYSIOLOGY • Increase Fluid Vol/Decrease Osmolarity • Drink pure H2O • Excrete dilute urine • Norm Fluid Vol/Increase Osmolarity • Salty popcorn (no drink) • Highly concentrated urine of low volume

25. HUMAN RENAL PHYSIOLOGY • Acid/Base Balance: • pH = measure of H+ concentration • Acids In Body: • Respiratory by-product (CO2 + H2O  HCO-3+ H+) • Amino acids • Fatty acids • Lactic acid • Ketoacids

26. HUMAN RENAL PHYSIOLOGY • Under Acidic Conditions: • Kidneys secrete H+ • Reabsorb HCO3-

27. HUMAN RENAL PHYSIOLOGY • Under Alkaline Conditions: • Kidneys conserve (retain) H+ • Secrete HCO3-

28. HUMAN RENAL PHYSIOLOGY • Urinalysis • White Blood Cells • Nitrites • Proteins • Glucose • Ketones • pH • Urobilinogen • Bilirubin

29. HUMAN RENAL PHYSIOLOGY • Try not to eat or drink 2 - 3 hours before lab • Exception: water • If you have dietary restrictions or a medical condition, please let your TA know