Proximal vs Distal Convoluted Tubule
Human kidneys are important organs located in the lower back and are responsible for many crucial functions including filtration, reabsorption and secretion. These functions basically carryout by a small unit called nephron; the functional and structural unit of the kidney. Nephron is composed of Bowman’s capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct. Proximal and distal tubules have convoluted structures and are very important in regulating pH of the blood by the reabsorption of ions. Both these tubules have different structures that support their basic function.
Proximal Convoluted Tubule
Proximal tubule connects the Bowmen’s capsule and the loop of Henle. Its inner epithelium is converted to a brush boarder in order to increase the efficiency of reabsorption. This tubule is basically responsible for reabsorb all the nutrient back into systemic blood from the filtrate. In addition, it also reabsorbs two-third of NaCl and water filtered into Bowmen’s capsule. Active transport of Na+ from the filtrate and into surrounding capillaries drives the reabsorption process.
Distal Convoluted Tubule
Distal convoluted tubule is located in between the loop of Henley and collecting duct. It does not have brush boarder in its lumen. Distal tubule helps to regulate pH of blood by regulating H+ ion concentration. Also, the regulation of calcium by hormones is taken place at distal convoluted tubule.
What is the difference between Proximal and Distal Tubule?
• Diameter of proximal tubule is larger than that of distal tubule.
• Epithelium of proximal tubule contains a brush boarder, whereas that of the distal tubule contains few short microvili.
• Proximal tubule has an irregular or star shaped lumen. In contrast, distal tubule has perfectly round lumen.
• Proximal tubule connects the Bowman’s capsule and nephron loop (loop of Henle), whereas distal tubule connects nephron loop and collecting duct.
• Distal tubule helps to regulate pH and ions like potassium, sodium, calcium content in the blood, whereas proximal tubule regulates salt, water, organic solutes (glucose and amino acids), potassium, urea, phosphate and citrate contents.