Formation in Human · Part 2

Chapter- Net filtration Pressure Glomerular hydrostatic pressure (Colloidal osmotic pressure Capsular hydrostatic pressure). Net filtration pressure mmHg ( mmHg mmHg) 10mmHg The effective glomerular pressure of mmHg results in ultrafiltration. Glomerular filtration rate (GFR) is the volume of filtrate formed min in all nephrons (glomerulus) of both the kidneys. In adults the GFR is approximately - 125mL/min. Blood from the glomerulus is passed out through the efferent arteriole. The smooth muscle of the efferent arteriole contract resulting in vasoconstriction. Table . shows the relative concentrations of substances in the blood plasma and the glomerular filtrate. The glomerular filtrate is similar to blood plasma except that there are no plasma proteins. In cortical nephrons, blood from efferent arteriole flows into peritubular capillary beds and enters the venous system carrying with it recovered solutes and water from the interstitial fluid that surrounds the tubule. Table . Concentration of substances in the blood plasma and in the glomerular filtrate Substance Concentration in blood Plasma/g dm - Concentration in glomerular filtrate/g dm - Water Proteins . . Aminoacids . . Glucose . . Urea . . Uric acid . . Creatinine . . Inorganic ions (mainly Na , K and Cl ) . . A person with cirrhosis of the liver has lower than normal levels of plasma proteins and higher than normal GFR. Explain why a decrease in plasma protein would increase GFR. ii) Tubular Reabsorption This involves movement of the filtrate back into the circulation. The volume of filtrate formed per day is around - L and the urine released is around . L per day, i.e., nearly % of the glomerular filtrate that has to be reabsorbed by the renal tubules as it contains certain substances needed by the body. This process is called selective reabsorption. Reabsorption takes place by the tubular epithelial cells in different segments of the nephron either by active transport or passive transport, diffusion and osmosis. Proximal Convoluted Tubule (PCT) - Glucose, lactate, amino acids,