1、Kidney Physiology,YU Yanqin, PhD Zhejiang University, School of Medicine,The paired kidneys form a filtrate of the blood that is modified by reabsorption and secretion; urine designated for excretion moves along the ureters to the bladder.,Overview Functions of the Kidney,Regulation of body fluid os
2、molality (渗透压) Production of hormones: Erythropoietin（促红细胞生成素）, Kinins（激肽） and Renin（肾素）, Prostaglandins（前列腺素），1,25-dihydroxycholecalciferol（1,25-羟基维生素D3） Regulation of electrolyte and water Excretion of waste products Regulation of acid and base,Structure of the Kidney,Nephron（肾单位）,Renal corpuscle（
3、肾小体）- Glomerulus （肾小球）- Bowmans capsule（肾小囊） Renal tubular system（肾小管） Proximal convoluted tubule Loop of Henle（髓袢）- Descending thick limb- Descending thin limb- Ascending thin limb- Ascending thick limb Distal convoluted tubuleCollecting duct system,Types of the Nephron,Cortical nephron（皮质肾单位） Juxt
4、amedullary nephron （近髓肾单位）,Differences between the Nephrons,Juxtaglomerular Apparatus（球旁复合体）,Juxtaglomerular cells球旁细胞Renin-producing granular cells Macula densa致密斑 Extraglomerular mesangial cells球外系膜细胞,The intersection of the macula densa in the distal tubule with the afferent and efferent arteriol
5、es forms the juxtaglomerular apparatus, which secretes the endocrine signal known as renin into blood in the afferent arteriole.,Blood Supply of the Kidney,1200 ml/min, 20 % of the cardiac output Cortex: 94 % Outer medulla: 5-6 %Inner medulla: 1 % two capillary networks,Autoregulation of Renal Blood
6、 Flow,Range of regulationBP: 80 170 mmHgMechanisms Myogenic mechanism 肌源学说 Flow dependent mechanism(Tubuloglomerular feedback管球反馈),1. Myogenic mechanism肌源学说,Arterial blood pressure contraction of the vascular smooth muscle constriction of the blood vessel the blood flow relatively constant,2. Tubulo
7、glomerular feedback管球反馈,Renal blood flow glomerular filtration Na+ content in the renal filtrate detection by the macula densa a signal sent to the renal arterial system restoration of the renal blood flow and glomerular filtration rate to normal,Neural Regulation of Renal Blood Flow,Activation of t
8、he renal sympathetic nerves constriction of the renal arterioles renal blood flow and glomerular filtration rate (GFR) ,Humoral Regulation of Renal Blood Flow,Norepinephrine去甲肾上腺素, Epinephrine肾上腺素, and Endothelin内皮素To constrict renal blood vessel and GFR Angiotensin II血管紧张素IITo constrict efferent ar
9、terioles Nitric Oxide一氧化氮 renal vascular resistance and GFR Prostaglandins 前列腺素and Bradykinin缓激肽Tend to increase GFR,Urine Formation,Filtration,Filtrate (glomerular urine原尿 )=blood plasma-proteins 180L/day Final urine终尿1.5L/day,Composition in the Filtration Fluid,Structure of the Filtration Membrane
10、, Capillary endothelium Basement membrane Epithelial cells of the visceral layer of the renal capsule,Permeability of the Filtration Membrane _Molecular barrier分子屏障, Capillary endotheliumFenestrae: 70 90 nm Basement membrane Meshwork of collagen & proteoglycan fibrillae:2 8 nm Epithelial cells of th
11、e visceral layer of the renal capsule Slit pore: 6 11 nm,Electrostatic Barrier 电荷屏障 of the Filtration Membrane,Negatively charged glycoproteins in the endothelial cells & basement membrane,Effective Filtration Pressure (有效滤过压，EFP),EFP = Hydrostatic pressure in the glomerulus肾小球毛细血管血压 (Oncotic pressu
12、re of plasma 血浆胶体渗透压+ Hydrostatic pressure of the liquid in the renal capsule肾小囊内压) The net filtration pressure (NFP),Glomerular Filtration,Glomerular filtration rate (肾小球滤过率，GFR) The quantity of the glomerular ultrafiltrate formed each minute in all nephrons of both kidneys GFR = Kf X Net filtratio
13、n pressureNormal value: 125 ml / minFiltration fraction (滤过分数，FF)FF = GFR / Renal plasma flowNormal value: 19%,Glomerular Capillary Filtration Coefficient (Kf), DefinitionThe product of the hydraulic conductivity and surface area of the glomerular capillaries= # of pores per unit area x total area o
14、f filtration Kf = GFR / Net filtration pressure,Factors Affecting Filtration,1) Glomerular hydrostatic pressure肾小球毛细血管血压 Late hypertension diameter of A. renal blood flow glomerular hydrostatic pressure GFR ,Factors Affecting Filtration,2) Colloid osmotic pressure of plasma血浆胶体渗透压Malnutrition Colloi
15、d osmotic pressure of plasma GFR 3) Bowmans capsule pressure肾小囊内压: stone or cancer,Factors Affecting Filtration,4) Renal plasma flow5) Filtration area滤过面积: 1.5m2Acute glomerulonephritis急性肾小球肾炎6) Permeability通透性 of the filtration membraneAlbuminuria蛋白尿 or hematuria血尿,Summary,TermsGlomerular filtration rateFiltration fractionNet filtration pressureFiltration coefficientTubuloglomerular feedback,Summary,List the factors affecting glomerular filtration,Intensive Reading,Textbook of Medical Physiology (Guyton & Hall)Page 282-288Page 290-293,
