PHGY 210 Lecture Notes - Lecture 2: Renal Function, Oncotic Pressure, Afferent Arterioles
15 Feb 2018
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Document Summary
Everything is usually filtered at the glomerular capillaries. A few examples: para-amino-hippurate (pah): what isn"t filtered continues in the blood and is then all secreted into the tubule. Not many substances like that: sodium, water: reabsorbed to some extent and the rest is secreted. Many are like this: glucose: 100% reabsorbed. The rate of filtration, reabsorption, or secretion is subject to physiological control. Water and low-molecular weight substances (i. e. k, na, aas) are freely filtered. Not freely filtered: cells, proteins (i. e. albumin, globulins), protein-bound substances (i. e. Not freely filtered: cells, proteins (i. e. albumin, globulins), protein-bound substances (i. e. 1/2 of ca ion, fatty acids). Pgc = glomerular capillary blood pressure is the favoring filtration force. Pbs = fluid pressure in bowman"s space, an opposing filtration force. pigc = oncotic pressure = osmotic force due to proteins in plasma, the other opposing filtration force. Net glomerular filtration pressure = pgc pbs pigc = about 16 mmhg.
