Figure 114

Tubular transport processes. Sodium excretion is the difference between the very high filtered load and net tubular reabsorption rate such that, under normal conditions less than 1% of the filtered sodium load is excreted. The percentage of reabsorption of the filtered load occurring in each nephron segment is shown. The end result is that normally less than 1% of the filtered load is excreted; however, the exact excretion rate can be changed by many mechanisms. Despite the lesser absolute sodium reabsorption in the distal nephron segments, the latter segments are critical for final regulation of sodium excretion. Therefore, any factor that changes the delicate balance existing between the hemodynamically determined filtered load and the tubular reabsorption rate can lead to marked alterations in sodium excretion. ALH—thin ascending limb of the loop of Henle; CCD—cortical collecting duct; DCT—distal convoluted tubule; DLH—thin descending limb of the loop of Henle; IMCD—inner medullary collecting duct; OMCD—outer medullary collecting duct; PCT—proximal convoluted tubule; PST—proximal straight tubule; TALH—thick ascending limb of the loop of Henle.

Peritubular capillary Lateral

Peritubular capillary Lateral

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