1. D. C. Mikulecky Faculty Mentoring Program Virginia Commonwealth Univ. 10/6/2015

2.  Water balance  Electrolyte balance  Plasma volume  Acid-base balance  Osmolarity balance  Excretion  Hormone secretion 10/6/2015

3.  Kidneys  Blood supply: Renal arteries and veins  Ureter  Urinary bladder  Urethra 10/6/2015

4. Bowman’s Capsule Glomerulus Proximal Convoluted Tubule Distal Convoluted Tubule Loop of Henle Cortex Medulla Artery Vein Peritubular Capillaries Collecting Duct

5.  Glomerular Filtration: Filtering of blood into tubule forming the primitive urine  Tubular Reabsorption: Absorption of substances needed by body from tubule to blood  Tubular Secretion: Secretion of substances to be eliminated from the body into the tubule from the blood 10/6/2015

6. GF TR TA Urine Excreted Efferent Arteriole Afferent Arteriole Glomerulus Kidney Tubule Peritubular Capillary

7.  First step in urine formation  180 liters/day filtered  Entire plasma volume filtered 65 times/day  Proteins not filtered 10/6/2015

8. Glomerular Capillary Blood Pressure + 55 Plasma Colloid Osmotic Pressure - 30 15 10 Bowman’s Capsule Hydrostatic Pressure - Net Filtration Pressure+

9.  Water: 99% reabsorbed  Sodium: 99.5% reabsorbed  Urea: 50% reabsobed  Phenol: 0% reabsorbed 10/6/2015

10.  By passive diffusion  By primary active transport: Sodium  By secondary active transport: Sugars and Amino Acids 10/6/2015

11. Lumen Plasma Cells

12. 10/6/2015 Lumen Plasma Cells PUMP: Na/K ATPase Sodium Potassium Chloride Water

13.  Stimulates Sodium Reabsorption in distal and collecting tubules  Naturetic peptide inhibits  In absence of Aldosterone, 20mg of sodium/day may be excreted  Aldosterone can cause 99.5% retention 10/6/2015

14. Fall in NaCl, extracellular fluid volume, arterial blood pressure Juxtaglomerular Apparatus ReninLiver Angiotensin + Aldosterone Lungs Converting Enzyme Adrenal Cortex Increased Sodium Reabsorption Helps Correct

15.  ACE Inhibitors (Angiotensin Converting Enzyme): Cause loss of salt---> water follows  Atrial Naturetic Peptide (ANP) also inhibits sodium reabsorption  Osmotic diuretics: Are not reabsorbed 10/6/2015

16.  They are actively transported across the apical cell membranes of the epithelial cells  Their active transport depends on the sodium gradient across this membrane  All other steps are passive 10/6/2015

17. Renal threshold (300mg/100 ml) Plasma Concentration of Glucose Glucose Reabsorbed mg/min Filtered Excreted Reabsorbed

18.  Protons (acid/base balance)  Potassium  Organic ions 10/6/2015

19. Lumen Plasma Cells PUMP: Na/K ATPase Sodium Potassium Chloride Water

20. 10/6/2015 Fall in sodium ECF Volume Blood Pressure Increased Plasma Potassium Increased Aldosterone secretion Increased Tubular Potassium Secretion Increased Urinary Potassium Secretion Increased Tubular Sodium Reabsorption Fall in Urinary Sodium Excretion

21.  Glucose and Amino Acids  67% of Filtered Sodium  Other Electrolytes  65% of Filtered Water  50% of Filtered Urea  All Filtered Potassium 10/6/2015

22.  Variable Proton secretion for acid/base regulation  Organic Ion secretion 10/6/2015

23.  Variable Sodium controlled by Aldosterone  Chloride follows passively  Variable water controlled by vasopressin 10/6/2015

24.  Variable Proton for acid/base regulation  Variable Potassium controlled by aldosterone 10/6/2015

25.  Variable water reabsorption controlled by vasopressin  Variable Proton secretion for acid/base balance 10/6/2015

26.  Medullary countercurrent system  Vasopressin 10/6/2015

27.  Osmotic gradient established by long loops of Henle  Descending limb  Ascending limb 10/6/2015

28.  Highly permeable to water  No active sodium transport 10/6/2015

29.  Actively pumps sodium out of tubule to surrounding interstitial fluid  Impermeable to water 10/6/2015

30. 300 450 600 750 900 1050 1200 From Proximal Tubule To Distal Tubule Cortex Medulla 300 450 600 750 900 1050 1200 100 250 400 550 700 850 1000 Active Sodium Transport Passive Water Transport Long Loop of Henle

31. 10/6/2015 From Distal Tubule Cortex Medulla 300 450 600 750 900 1050 1200 300 400 550 700 850 1000 1100 1200 Interstitial Fluid Collecting Duct Pores Open Passive Water Flow

32. 10/6/2015 From Distal Tubule Cortex Medulla 300 450 600 750 900 1050 1200 100 Interstitial Fluid Collecting Duct Pores Closed No Water Flow Out of Duct

33.  Acute: Sudden onset, rapid reduction in urine output - usually reversible  Chronic: Progressive, not reversible  Up to 75% function can be lost before it is noticeable 10/6/2015

34.  Gravity and peristaltic contractions propel the urine along the ureter  Parasympathetic stimulation contracts the bladder and micturition results if the sphincters (internal and external urethral sphincters) relax  The external sphincter is under voluntary control 10/6/2015

35.  Bladder filling reflexively contracts the bladder  Internal Sphincter mechanically opens  Stretch receptors in bladder send inhibitory impulses to external sphincter  Voluntary signals from cortex can override the reflex or allow it to take place 10/6/2015