2.2 regulation ofrenal blood flow (1)Autoregulation:perfusion pressure at 80~180mmHg (2)Sympathetic nervous system and hormonal or autacoid control of renal blood flow. Seaction2 Urine Formation The formation of urine includes three basic processes:glomerular filtration; reabsorption in the renal tubule and collecting duct;secretion and excretion in the renal tubule and collecting duct. 1.Glomerular filtration Glomerular filtration rate:The rate at which fluid filters from the blood into Bowman's capsule. (1)the glomerular capillary membrane and its permeability Glomerular filtration barrier:Glomerular capillary endothelium;basal lamina; epithelium (2)Effective filtration pressure(EFP) EFP=glomerular hydrostatic pressure -(glomerular colloid osmotic pressure+Bowman's capsule pressure) 2.Reabsorption in the renal tubule and collecting duct The proximal tubule is the main site of reabsorption where glucose,amino acids and vitamins are completely reabsorbed.CI-,HCO3-,and H2O are partly reabsorbed,while creatinine is not absorbed at all.The reabsorption is selective and independent of hormone control.Na+and K*are reabsorbed actively,glucose and amino2.2 regulation of renal blood flow (1) Autoregulation: perfusion pressure at 80～180mmHg (2) Sympathetic nervous system and hormonal or autacoid control of renal blood flow. Seaction2 Urine Formation The formation of urine includes three basic processes: glomerular filtration; reabsorption in the renal tubule and collecting duct; secretion and excretion in the renal tubule and collecting duct. 1. Glomerular filtration Glomerular filtration rate: The rate at which fluid filters from the blood into Bowman’s capsule. (1) the glomerular capillary membrane and its permeability Glomerular filtration barrier: Glomerular capillary endothelium; basal lamina; epithelium (2) Effective filtration pressure (EFP) EFP= glomerular hydrostatic pressure － (glomerular colloid osmotic pressure+Bowman’s capsule pressure) 2. Reabsorption in the renal tubule and collecting duct The proximal tubule is the main site of reabsorption where glucose,amino acids and vitamins are completely reabsorbed.Cl- ,HCO3- ,and H2O are partly reabsorbed,while creatinine is not absorbed at all.The reabsorption is selective and independent of hormone control.Na+ and K+are reabsorbed actively,glucose and amino