What is the Difference Between Proximal and Distal Convoluted Tubule?

The proximal convoluted tubule (PCT) and distal convoluted tubule (DCT) are two distinct segments of the nephron in the kidneys, responsible for different functions in the urine formation process. Here are the main differences between them:

1. Location and structure: The PCT is located in the cortex and connects the Bowman's capsule to the loop of Henle, while the DCT is located between the loop of Henle and the collecting duct. The PCT has a convoluted portion and a straight portion, while the DCT has a more linear structure.
2. Epithelium and brush border: The epithelium of the PCT is taller and contains a brush border, which is composed of microvilli that facilitate the reabsorption of small peptides and nutrients. In contrast, the epithelium of the DCT is slightly flatter, more basophilic, and contains fewer short microvilli.
3. Function: The PCT is responsible for reabsorbing fluid, electrolytes, and nutrients, accounting for roughly 98% of glucose and 65% of sodium reabsorption. The DCT, on the other hand, is mainly concerned with regulating the pH and ion content in the blood, such as potassium, sodium, and calcium.
4. Reabsorption: The PCT is involved in active transport of sodium, which drives the reabsorption of fluid and electrolytes. The DCT continues the active sodium reabsorption process and is also involved in the regulation of calcium by hormones.
5. Diameter: The diameter of the PCT is larger than that of the DCT.

Comparative Table: Proximal vs Distal Convoluted Tubule

The proximal convoluted tubule (PCT) and distal convoluted tubule (DCT) are two segments of the nephron in the kidneys that play crucial roles in the process of filtered fluid transport and reabsorption. Here is a table highlighting the differences between the two:

The PCT is responsible for reabsorbing a large amount of fluid and solutes, while the DCT plays a role in fine-tuning the reabsorption process and secreting potassium. The PCT has a high capacity for reabsorption and is lined with specialized cells to aid in this process. In contrast, the DCT comprises several morphologically and functionally heterogeneous subsegments and participates in various homeostatic processes.