Func%ons of the Urinary System Excre%on Diaphragm Regula%on of blood volume 11th and 12th ribs Adrenal gland Renal artery Renal vein Regula%on of blood pressure Kidney Vertebra L2 Aorta Inferior vena cava Regula%on of blood- solute concentra%on Regula%on of ph of extracellular fluid Ureter Urinary bladder Regula%on of erythropoiesis Urethra Synthesis of vitamin D (b) Posterior view (a) Anterior view 1 2 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 3 4 Renal capsule Renal cortex Nephron CollecHng duct Renal medulla (a) Renal corpuscle: Glomerular capsule Glomerulus Minor calyx Renal papilla CorHcal nephron Efferent arteriole Convoluted tubules (PCT and DCT) Afferent arteriole Proximal convoluted tubule (PCT) Nephron loop: Descending limb Ascending limb Juxtamedullary nephron Distal convoluted tubule (DCT) Cortex Medulla CollecHng duct (CD) Thick segment Thin segment Key Nephron loops Flow of blood Flow of tubular fluid (b) CollecHng duct Papillary duct 5 (c) 6
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 9 10 11 12 Turned back: Blood cells Plasma proteins Large anions Protein- bound minerals and hormones Most molecules > 8 nm in diameter Bloodstream 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 Uric acid CreaHnine Capsular space
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 13 Urine 14 Reduced GFR High GFR SympatheHc nerve fiber Podocytes Mesangial cells Efferent arteriole ConstricHon of afferent arteriole Sensed by macula densa Paracrine secrehon Juxtaglomerular cells Afferent arteriole Smooth muscle cells Nephron loop Rapid flow of filtrate in renal tubules Macula densa 15 16 Glucose Amino acids Protein Vitamins Lactate Uric acid Ca2+ Mg2+ HCO3 PCT HCO3 DCT H+ NH4+ H+ NH4+ Uric acid CreaHnine Some drugs Nephron loop: Descending limb Ascending limb CollecHng duct Key Tubular reabsorphon 17 Tubular secrehon 18
19 20 21 22 23 24
25 26 1 More salt is conhnually added by the PCT. 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. 400 200 600 400 3 The more water that leaves the descending limb, the salher the fluid is that remains in the tubule. 900 700 4 The salher the fluid in the ascending limb, the more salt the tubule pumps into the ECF. 1,200 27 28 29 30
Copyright The McGraw- Hill Companies, Inc. Permission required for reproduc%on or display. Drop in blood pressure Liver Angiotensinogen (453 amino acids long) Renin 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 33 34 35 36
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