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1-2. Urinary Physiology ___________________________________________ 3. Function Review ___________________________________________ Ureter-Carry urine from kidney to bladder ___________________________________________ Bladder - Temporary storage of urine ___________________________________________ Micturition ___________________________________________ 4-5.Micturition ___________________________________________ Bladder ___________________________________________ Smooth muscle -Detrusor ___________________________________________ Filling of bladder ___________________________________________ activates stretch receptors ___________________________________________ impulses to micturition center in sacral ___________________________________________ spinal cord ___________________________________________ Parasympathetic ___________________________________________ Contraction of detrusor ___________________________________________ Relaxation of internal urethral sphincter ___________________________________________ Voluntary relaxation of external urethral ___________________________________________ sphincter ___________________________________________ 6-7. Kidney Functions Major organ of excretion ___________________________________________ ___________________________________________ Waste products of metabolism ___________________________________________ Urea – Creatinine - Uric acid ___________________________________________ Foreign compounds ___________________________________________ Maintain plasma volume ___________________________________________ Maintain water balance/osmolarity ___________________________________________ Regulate quantity and concentration of most ___________________________________________ ECF ions ___________________________________________ Maintain acid-base balance ___________________________________________ Renin production ___________________________________________ Erythropoietin production ___________________________________________ Conversion of vitamin D to active form ___________________________________________ 8-9. Kidney Anatomy ___________________________________________ 10-11. The Nephron ___________________________________________ Blood processing ___________________________________________ Urine forming ___________________________________________ Functional unit ___________________________________________ Renal corpuscle ___________________________________________ Glomerulus ___________________________________________ ___________________________________________ Bowman’s capsule Renal tubule ___________________________________________ ___________________________________________ Proximal ___________________________________________ Loop of Henle ___________________________________________ Distal ___________________________________________ Collecting tubule ___________________________________________ 12. Vascular Component ___________________________________________ Afferent arteriole ___________________________________________ Glomerulus ___________________________________________ Capillaries ___________________________________________ Efferent arteriole ___________________________________________ Peritubular capillaries ___________________________________________ 13-14. Renal Circulation Review ___________________________________________ 15-16. Tubular Component ___________________________________________ Glomerular capsule ___________________________________________ Space continuous with renal tubule ___________________________________________ Parietal ___________________________________________ Squamous epithelium Visceral ___________________________________________ ___________________________________________ Podocytes ___________________________________________ 17-18. Podocytes ___________________________________________ Modified branching epithelial cells Foot processes ___________________________________________ ___________________________________________ Interdigitate ___________________________________________ Filtration slits or slit pores ___________________________________________ 19-20. Filtration Membrane ___________________________________________ Capillary fenestrations ___________________________________________ Everything x blood cells Basement membrane ___________________________________________ ___________________________________________ Everything x medium-large proteins ___________________________________________ Size and charge ___________________________________________ Slit diaphragms ___________________________________________ 21. Renal Tubule ___________________________________________ Simple epithelium on basement membrane Proximal convoluted tubule (PCT) ___________________________________________ Microvilli Loop of Henle Ascending/descending ___________________________________________ ___________________________________________ ___________________________________________ ___________________________________________ Thin segment/thick segment ___________________________________________ Distal convoluted tubule (DCT) ___________________________________________ Collecting duct ___________________________________________ 22. Capillary Bed ___________________________________________ Afferent arteriole Efferent venule Pressure drop over capillary bed 23. Glomerular Capillary Bed ___________________________________________ ___________________________________________ ___________________________________________ ___________________________________________ ___________________________________________ ___________________________________________ Afferent arteriole ___________________________________________ Capillaries fenestrated ___________________________________________ Efferent arteriole ___________________________________________ 24. Peritubular Capillaries ___________________________________________ Arise from efferent arterioles ___________________________________________ Cling to renal tubule ___________________________________________ Low pressure, fenestrated ___________________________________________ Empty into venules ___________________________________________ 25. Vasa Recta ___________________________________________ Capillaries ___________________________________________ Long straight vessels ___________________________________________ Juxtamedullary nephrons ___________________________________________ Parallel to loops of Henle ___________________________________________ 26. Juxtaglomerular Apparatus ___________________________________________ DCT and afferent arteriole ___________________________________________ Juxtaglomerular cells in arteriole ___________________________________________ Macula densa in DCT ___________________________________________ 27. Renal Physiology ___________________________________________ 28. Glomerular Filtration ___________________________________________ Passive ___________________________________________ Mechanical filter ___________________________________________ Efficiency ___________________________________________ Porous ___________________________________________ Large surface area ___________________________________________ High glomerular pressures ___________________________________________ 29. Net Filtration Pressure ___________________________________________ NFP = PGC + πBC– (PBC + πGC) ___________________________________________ PGC ___________________________________________ Glomerular hydrostatic pressure ___________________________________________ Fluid and solids move into capsular space ___________________________________________ πBC ___________________________________________ Osmotic pressure - negligible πGC ___________________________________________ ___________________________________________ Osmotic pressure of blood ___________________________________________ Opposes HPg ___________________________________________ PBC ___________________________________________ Hydrostatic pressure of capsule ___________________________________________ Opposes HPg ___________________________________________ 30. Glomerular Filtration Rate ___________________________________________ Volume of filtrate formed each minute ___________________________________________ Determined by: ___________________________________________ Surface area available for filtration ___________________________________________ Filtration membrane permeability ___________________________________________ NFP ___________________________________________ 100-125cc/min ___________________________________________ 31-32. Regulation of Filtration Rate Intrinsic ___________________________________________ ___________________________________________ Renal autoregulation Myogenic ___________________________________________ ___________________________________________ Vascular smooth muscle Tubuloglomerular feedback mechanism ___________________________________________ ___________________________________________ Macula densa cells of justaglomerular ___________________________________________ apparatus ___________________________________________ Extrinsic ___________________________________________ Neural ___________________________________________ Sympathetic ___________________________________________ Constriction of afferent arterioles ___________________________________________ Stimulate JG cells to produce renin ___________________________________________ Hormonal ___________________________________________ Renin-angiotensin 33-34. Renin-Angiotensin Mechanism Renin ___________________________________________ ___________________________________________ Enzyme ___________________________________________ Angiotensinogen angiotension I Angiotensin converting enzyme (ACE) Angiotensin I ___________________________________________ angiotensin II ___________________________________________ ___________________________________________ ___________________________________________ Potent vasoconstriction ___________________________________________ Na+ absorption ___________________________________________ Aldosterone release ___________________________________________ 35-37. Tubular Reabsorption ___________________________________________ Filtrate = urine ___________________________________________ 180L/day ___________________________________________ 1.5L/day Movement of substances back into blood ___________________________________________ Water, small proteins, amino acids, glucose, ___________________________________________ ions, etc. ___________________________________________ Tight junctions ___________________________________________ Luminal membrane ___________________________________________ Cytosol of tubular cell ___________________________________________ Basolateral membrane of tubular cells ___________________________________________ Interstitial fluid ___________________________________________ Capillary endothelium ___________________________________________ 38. Sodium Reabsorption ___________________________________________ Transcellular ___________________________________________ Passive ___________________________________________ Luminal membrane ___________________________________________ Na+ channels or facilitated diffusion ___________________________________________ Active transport Basolateral membrane Peritubular capillary ___________________________________________ ___________________________________________ ___________________________________________ Passive ___________________________________________ 39. Nutrients ___________________________________________ Na+ movement Secondary active transport Common carrier (symport) ___________________________________________ ___________________________________________ ___________________________________________ Glucose ___________________________________________ Amino acids ___________________________________________ Transport maximum ___________________________________________ 40. Water and Ions Na+ movement Passive Electrical gradient - Cl , HCO3- Osmotic gradient ___________________________________________ ___________________________________________ ___________________________________________ ___________________________________________ ___________________________________________ Aquaporins ___________________________________________ Water reabsorption ___________________________________________ Solutes follow solvent ___________________________________________ 41-45. Distal Tubule/Collecting Tubule ___________________________________________ Dependent on need and hormonal regulation ___________________________________________ ADH ___________________________________________ Aquaporins in collecting tubule ___________________________________________ Water reabsorption ___________________________________________ Aldosterone ___________________________________________ + + Na reabsorption/K secretion ___________________________________________ Water reabsorption ___________________________________________ 46-47. Tubular Secretion ___________________________________________ Movement of substances from peritubular ___________________________________________ capillaries or tubule cells into filtrate ___________________________________________ Substances not already in filtrate, e.g. drugs ___________________________________________ Waste products such as urea and uric acid ___________________________________________ + Excess K ___________________________________________ Control of blood pH ___________________________________________ 48-49. Potassium Ion Secretion ___________________________________________ Selectively moved in opposite directions in ___________________________________________ different parts of the renal tubules ___________________________________________ Controlled by aldosterone ___________________________________________ Sectreted by proximal, distal, and collecting ___________________________________________ tubules ___________________________________________ 50. Hydrogen Ion Secretion ___________________________________________ Important in acid-base balance ___________________________________________ Sectreted by proximal, distal, and collecting ___________________________________________ tubules ___________________________________________ 49-51. ___________________________________________ 51-52. Organic Ion Secretion Proximal tubule ___________________________________________ ___________________________________________ Cation system ___________________________________________ Anion system ___________________________________________ 53-60. Osmotic Gradient ___________________________________________ Body fluids - 300mOsm ___________________________________________ PCT - 300mOsm ___________________________________________ Deep Medulla - 1200mOsm ___________________________________________ The Loop of Henle ___________________________________________ Descending loop ___________________________________________ Thin ___________________________________________ Impermeable to solutes ___________________________________________ Freely permeable to water ___________________________________________ Ascending loop ___________________________________________ Thick ___________________________________________ Permeable to solutes ___________________________________________ Impermeable to water ___________________________________________ 62-65. Antidiuretic Hormone ___________________________________________ Vasopressin ___________________________________________ Inhibits urine formation ___________________________________________ Aquaporins inserted into luminal membrane ___________________________________________ Facultative water reabsorption ___________________________________________ Necessary for production of concentrated urine ___________________________________________ 66. Collecting Duct (CD) ___________________________________________ Plays important role in water conservation ___________________________________________ Is impermeable to salt in medulla ___________________________________________ Permeability to H2O depends on levels of ADH ___________________________________________ 67. Electrolyte Balance ___________________________________________ Na+, K+, H+, HCO3-, Cl-, and PO4-3 regulated by ___________________________________________ matching excretion to ingestion ___________________________________________ Na+ ___________________________________________ regulation of blood volume and pressure K+ ___________________________________________ ___________________________________________ proper function of muscle 68. Role of Aldosterone 90% filtered Na+ and K+ reabsorbed before DCT ___________________________________________ ___________________________________________ ___________________________________________ Variably reabsorbed in distal nephron ___________________________________________ Aldosterone ___________________________________________ controls K+ secretion and Na+ reabsorption ___________________________________________ absence ___________________________________________ 80% of remaining Na+ is reabsorbed in ___________________________________________ DCT and cortical CD ___________________________________________ high ___________________________________________ all remaining Na+ is reabsorbed 69. K+ Secretion + ___________________________________________ ___________________________________________ Is only way K ends up in urine ___________________________________________ Is directed by aldosterone and occurs in DCT ___________________________________________ and cortical CD ___________________________________________ High K+ or low Na+ will increase aldosterone ___________________________________________ and K+ secretion ___________________________________________ 70.Atrial Natriuretic Peptide (ANP) ___________________________________________ Is produced by atria due to stretching of walls ___________________________________________ Acts opposite to aldosterone ___________________________________________ Stimulates salt and H2O excretion ___________________________________________ Acts as an endogenous diuretic ___________________________________________ 71-73. Renal Acid-Base Regulation + Kidneys excrete H and/or reabsorb ___________________________________________ HCO3- ___________________________________________ Most H+ secretion occurs across walls of PCT in ___________________________________________ exchange for Na+ (Na+/H+ antiporter) ___________________________________________ Normal urine is slightly acidic (pH = 5-7) ___________________________________________ because kidneys reabsorb almost all HCO3- and ___________________________________________ excrete H+ ___________________________________________ When urine is acidic, HCO3- combines with H+ to ___________________________________________ form ___________________________________________ H2CO3 (catalyzed by CA on apical membrane of PCT cells) ___________________________________________ H2CO3 dissociates into CO2 + H2O ___________________________________________ CO2 diffuses into PCT cell and forms H2CO3 78. Urinalysis (catalyzed by CA) Physical Characteristics H2CO3 splits into HCO3- and H+ ; HCO3- diffuses Color Pale yellow into blood Transparency Transparent 74. Urinary Buffers Odor 4.5 – 8.0 Nephron cannot produce urine with pH < 4.5 pH Excretes more H+ by buffering H+s with HPO4-2 Specific gravity 1.015 – 1.025 or NH3 before excretion Phosphate enters tubule during filtration Ammonia produced in tubule by deamination of Inorganic components Nitrites Absent Organic Components aminoacids Buffering reactions Glucose Negative HPO4-2 + H+ H2PO4- Albumin Negative NH3 + H+ NH4+ (ammonium ion) Ketone bodies Negative Bilirubin Negative Yellow, Slightly aromatic, pH usually acidic Urobilinogen Present Specific gravity RBC’s, WBCs, Negative 75-77. Urine Comparison to weight of equal amount of Microscopic Analysis Crystals Negative 95% water RBC’s, WBC’s Negative 5% solutes Epithelial cells Trace ok Casts Negative distilled water, 1.001 to 1.035 Urea, Na+, K+, PO43-, SO42, Creatinine,Uric acid
