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Chapter 14 the Kidneys and Regulation of Water and Inorganic

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Chapter 14 the Kidneys and Regulation of Water and Inorganic Chapter 14 The Kidneys and Regulation of Water and Inorganic Ions Functions of the kidneys Urea, uric acid, creatinine Drugs, pesticides, food additives Amino acids → glucose Urinary system in a women Gross anatomy of the kidney Kidney: (1) 11 cm long, 6 cm wide, 4 cm deep, 115-170 g (2) Right kidney is lower than left kidney (3) Outer: Cortex → blood filtration 腎錐 Middle: Medulla (8-18 renal pyramids) → urine collection Inner: papilla → minor calyx → major calyx → renal pelvis → 腎乳頭ureter → urinary bladder 腎盞 腎盂 輸尿管 膀胱 Nephron: 腎元 (1) 1,000,000 nephrons/kidney (2) The functionl unit of the kidney (the glomerulus + the renal tubule) 腎小球/腎絲球/絲球體 腎小管 To urinary bladder Section of a human kidney Renal pyramid Minor calyx Major calyx Loops of Henle + Collecting ducts Papilla Basic structure of a nephron 106 nephrons/kidney 腎小體 腎小球 遠曲小管接觸入球微動脈後 鮑氏囊 產生一特化組織 緻密斑 Part of thick segment of ascending limb 亨爾氏套 直管 近髓質腎元 皮質腎元 10-15% 80-85% Nephron types and the collecting duct system Receive 90% of renal blood supply Renal corpuscle; Glomerular capillaries Glomerular capsule Glomerular (Bowman) capsule PCT → PST → DTL → ATL → TAL → DCT → CNT → CCD → OMCD → IMCD Loop of Henle CD Basic structure of a nephron Nephron Anatomy of the renal corpuscle 近腎小球複合體 JGA Thick segment of ascending limb Glomerular filtrate Cell-free, protein-free (20% of the plasma) 足細胞 窗孔 Mesangial cells The glomerulus and its filtration barrier Pore size 70 nm GFR (glomerular filtration rate) = Kf [(PGC-PBS) - (GC-BS)] Hydrostatic Colloid osmotic pressure pressure GC: glomerular capillary BS: Bowmen space < 5,000 Da (1) Lamina rara interna (2) Lamina densa Lamina rara externa (3) 濾過裂隙隔膜 TEM of a glomerular capillary and the glomerular membranes Podocytes (fltration slits) Basement membrane Endothelia (fenestrae) The juxtaglomerular apparatus (JGA) 近腎小球複合體 系膜細胞 近腎小球細胞 (JG) Renin JGA The juxtaglomerular apparatus Tubuloglomerular feedback (TGF) Adenosine receptor A2 → Dilation Cl- Na+/K+/Cl- Na+-K+-2Cl- cotransporter RBF Adenosine (renal blood flow) GFR Gap junctions between juxtaglomerular apparatus (JGA) cells (glomerular filtration macula densa → mesangial cells → afferent arteriole rate) Adenosine receptor A1 → Constriction RAAS (renin-angiotensin-aldosterone system) angiotensinogen Renin angiotensin I ACE (angiotensin-converting enzyme) angiotensin II Tubuloglomerular feedback AA: afferent arteriole EA: efferent arteriole PUF: capillary hydrostatic ultrafiltration pressure GFR: glomerular filtration rate The three basic components of renal function @ renal corpuscle @ varies sites along the tubule Not all these processes apply to all substances Amount Amount Amount Amount =+ - excreted filtered secreted reabsorbed Renal handling of three hypothetical filtered substrances Forces involved in glomerular filtration Forces favoring glomerular ultrafiltration PBS: Bowman space PGC: glomerular capillary hydrostatic pressure : glomerular capillary colloid osmotic pressure GC + 20 mm Hg + 8 mm Hg Forces controlling fluid reabsorption by peritubular capillaries PC 25 mm Hg in all other regions of PC the body 35 mm Hg 20 mm Hg Other systemic capillary beds 35 mm Hg Control of GFR by constriction or dilation of afferent aRterioles (AA) or efferent arterioles (EA) GFR (glomerular filtration rate) AA: afferent arteriole EA: efferent arteriole Average values for several components that undergo filtration and reabsorption Diagrammatic representation of tubular epithelium Transcellular route (by transporters) Paracellular route (by diffusion) Apical Pathways for reabsorption from the tubule lumen Determined by tight junction structure Requires the assistance of channels or transporters ATP-dependent pumps The relationship between plasma glucose concentration and the rate of glucose filtered (filtered load), reabsorbed, or excreted The maximum rate at which glucose can be absorbed Example of renal handling of inulin The clearance of inulin is equal to the glomerular filtration rate Ureters 2-6 cm/s Transitional epithelium is a type of tissue consisting of multiple layers of epithelial cells which can contract and expand Circular and longitudinal smooth muscle layers The urinary bladder 腹下神經 SNS: T11-L2, hypogastric nerve (1) detrusor relaxation (2) bladder neck & urethra contraction 骨盆神經 PSNS: S2-S4, pelvic nerve (1) detrusor contraction (2) urethra internal sphincter relaxation Transitional epithelium 皺襞 會陰神經 Pudendal nerve from the sacral spinal cord Intravascular ureteral valve preventing urine reflex Control of the bladder Average daily water gain and loss in adults Daily sodium chloride intake and loss Mechanism of Na+ reabsorption in the proximal tubule and cortical collecting duct Coupling of water and Na+ reabsorption The regulation and function of aquaporins (AQPs) in the medullary-collecting-duct cells to increase water reabsorption ADH receptor ADH Vasopressin-sensitive Vasopressin-insensitive 尿崩症 Diabetes insipidus caused by the failure to release vasopressin or non-respond to vasopressin 25 L/day Generating a hyperosmolar medullary renal interstitium Countercurrent multiplier system Impermeable to H2O Simplified depiction of the generation of an interstitial fluid osmolarity gradient by the renal countercurrent multiplier system and its role in the formation of hyperosmotic urine in the presence of vasopressin Functions of the vasa recta to maintain the hypertonic interstitial renal medulla Urea recycling Direct and neurally mediated reflex pathways when plasma volume decreases Summary of the renin-angiotensin system and the stimulation of aldosterone secretion by angiotensin II RAAS (renin-angiotensin-aldosterone system) ACE @ cortical collecting ducts Pathways by which decreased plasma volume leads to increased Na+ reabsorption Atrial natriuretic peptide (ANP) increases Na+ excretion Cortical Osmoreceptor pathway that decreases vasopressin secretion and increases water excretion when excess water is ingested ADH Medullary Baroreceptor pathway by which vasopressin secretion increases when plasma volume decreases Medullary Pathways by which Na+ and water excretion decrease in response to severe sweating Inputs controlling thirst Simplified model of the basic renal processing of potassium Pathways by which an increased potassium intake induces greater K+ excretion Summary of the control of aldosterone and its effects on Na+ absorption and K+ secretion Summary of “Division of labor” in the renal tubules Sources of hydrogen ion gain and loss - Reabsorption of HCO3 H+-ATPase or Na+/H+ countertransporters H+/K+-ATPase pumps - Renal contribution of new HCO3 to the plasma as achieved by tubular secretion of H+ H+-ATPase or Na+/H+ countertransporters H+/K+-ATPase pumps - Renal contribution of new HCO3 to the plasma as achieved by + renal metabolism of glutamine and excretion of ammonium (NH4 ) Proximal tubule Renal responses to acidosis and alkalosis + - Changes in the arterial concentrations of H , HCO3 , and carbon dioxide in acid-base disorders Simplified diagram of hemodialysis 400 mL/min 1000 mL/min.
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