Urine Formation I Glomerular Filtration
Objectives
When you have completed this section, you should be able to
• describe the glomerular filtration membrane and how it excludes blood cells and proteins from the filtrate;
• explain the forces that promote and oppose glomerular filtration, and calculate net filtration pressure if given the magnitude of these forces; and
• describe how the nervous system, hormones, and the kidney itself regulate glomerular filtration.
The kidney converts blood plasma to urine in three stages: glomerular filtration, tubular reabsorption and secretion, and water conservation (fig. 23.8). As we trace fluid through the nephron, we will refer to it by different names that reflect its changing composition: (1) The fluid in the capsular space, called glomerular filtrate, is similar to blood plasma except that it has almost no protein. (2) The fluid from the proximal convoluted tubule through the distal convoluted tubule will be called tubular fluid. It differs from the glomerular filtrate because of substances removed and added by the tubule cells. (3) The fluid will be called urine once it enters the collecting duct.
Post a comment