Func%ons of the Urinary System Excre%on Regula%on of blood volume Regula%on of blood pressure Regula%on of blood- solute concentra%on Regula%on of ph of extracellular fluid Regula%on of erythropoiesis Synthesis of vitamin D 1 Copyright The McGraw- Hill Companies, Inc. Permission required for reproduc%on or display. Diaphragm 11th and 12th ribs Adrenal gland Renal artery Renal vein Kidney Vertebra L2 Aorta Inferior vena cava Ureter Urinary bladder Urethra (a) Anterior view (b) Posterior view 2
3 Copyright The McGraw- Hill Companies, Inc. Permission required for reproduc%on or display. Fibrous capsule Renal cortex Renal medulla Renal papilla Renal sinus Adipose Hssue in renal sinus Renal pelvis Major calyx Minor calyx Renal column Renal pyramid Ureter Renal blood vessels (a) (b) a: Ralph Hutchings/Visuals Unlimited 4
5 Copyright The McGraw- Hill Companies, Inc. Permission required for reproduc%on or display. Renal capsule Renal cortex Nephron CollecHng duct Efferent arteriole Renal medulla (a) Renal corpuscle: Glomerular capsule Glomerulus Minor calyx Renal papilla CorHcal nephron Convoluted tubules (PCT and DCT) Afferent arteriole Proximal convoluted tubule (PCT) Distal convoluted tubule (DCT) Juxtamedullary nephron Cortex Medulla Nephron loop: Descending limb Ascending limb CollecHng duct (CD) Thick segment Thin segment (b) Key Flow of blood Flow of tubular fluid Nephron loops CollecHng duct Papillary duct (c) 6
Copyright The McGraw- Hill Companies, Inc. Permission required for reproduc%on or display. CorHcal nephron Afferent arteriole Glomerulus Juxtamedullary nephron Efferent arteriole C o r t e x PCT Interlobular artery DCT Interlobular vein Peritubular capillaries CorHcomedullary junchon Arcuate artery Arcuate vein Vasa recta M e d u l l a CollecHng duct Nephron loop 7 8
Copyright The McGraw- Hill Companies, Inc. Permission required for reproduc%on or display. Turned back: Blood cells Plasma proteins Large anions Protein- bound minerals and hormones Most molecules > 8 nm in diameter Endothelial cell of glomerular capillary Basement membrane FiltraHon slit FiltraHon pore Foot process of podocyte Passed through filter: W ater Electrolytes Glucose Amino acids FaVy acids Vitamins Urea Uric acid CreaHnine Bloodstream Capsular space 9 10
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Copyright The McGraw- Hill Companies, Inc. Permission required for reproduc%on or display. Blood flow 1 Glomerular filtrahon Creates a plasmalike filtrate of the blood Rental Corpuscle Flow of filtrate 2 Tubular reabsorphon Removes useful solutes from the filtrate, returns them to the blood and Peritubular Capillaries Tubular secrehon Removes addihonal wastes from theblood, adds them to the filtrate Rental tubule 3 water conservahon Removes water from the urine and returns it to_ blood; cincentrates wastes Urine 13 14
Copyright The McGraw- Hill Companies, Inc. Permission required for reproduc%on or display. SympatheHc nerve fiber Podocytes Mesangial cells Efferent arteriole Juxtaglomerular cells Nephron loop Afferent arteriole Smooth muscle cells Macula densa 15 Copyright The McGraw- Hill Companies, Inc. Permission required for reproduc%on or display. High GFR Reduced GFR Rapid flow of filtrate in renal tubules ConstricHon of afferent arteriole Sensed by macula densa Paracrine secrehon 16
17 Copyright The McGraw- Hill Companies, Inc. Permission required for reproduc%on or display. Glucose Na + Amino acids K + Protein Ca 2+ Vitamins Mg 2+ Lactate Cl Urea HCO 3 Uric acid PCT Na + Cl HCO 3 DCT Urea H + Uric acid NH + 4 CreaHnine Some drugs Nephron loop: Descending limb Ascending limb Na + K + Cl CollecHng duct H + K + NH 4 + Urea Urea Key Tubular reabsorphon Tubular secrehon 18
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27 1 More salt is conhnually added by the PCT. Copyright The McGraw- Hill Companies, Inc. Permission required for reproduc%on or display. 300 100 5 The more salt that is pumped out of the ascending limb, the salher the ECF is in the renal medulla. 2 The higher the osmolarity of the ECF, the more water leaves the descending limb by osmosis. 400 600 Na + K + Cl Na + K + Cl 200 400 Na + K + Cl Na + K + Cl 3 The more water that leaves the descending limb, the salher the fluid is that remains in the tubule. 900 Na + K + Cl 700 4 Na + K + Cl The salher the fluid in the ascending limb, the more salt the tubule pumps into the ECF. 1,200 28
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Copyright The McGraw- Hill Companies, Inc. Permission required for reproduc%on or display. Drop in blood pressure Liver Renin Angiotensinogen (453 amino acids long) Kidney Angiotensin I (10 amino acids long) Angiotensin- converhng enzyme (ACE) Angiotensin II (8 amino acids long) Lungs Hypothalamus Cardiovascular system Adrenal cortex Aldosterone VasoconstricHon Kidney Thirst and drinking Elevated blood pressure Sodium and water retenhon 31 32
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