Most of the useful portion of filtrate gets past the PCT. false true
The correct answer and explanation is:
The correct answer is True.
In the renal system, the proximal convoluted tubule (PCT) plays a crucial role in the reabsorption of essential substances from the filtrate back into the bloodstream. The majority of the useful portion of the filtrate, including glucose, amino acids, and electrolytes like sodium, potassium, and bicarbonate, is reabsorbed here. This reabsorption occurs through active and passive transport mechanisms, ensuring that these essential substances are conserved by the body.
The PCT is lined with specialized cells that have microvilli, increasing the surface area for absorption. The reabsorbed substances then enter the peritubular capillaries, which surround the nephron, and are transported back into the bloodstream. This process is highly efficient, with nearly 65-70% of the filtrate’s water and solutes reabsorbed in the PCT.
While the PCT is responsible for most of the filtrate’s reabsorption, the loop of Henle, distal convoluted tubule (DCT), and collecting duct also contribute to fine-tuning the composition of urine. For example, the loop of Henle primarily handles water and salt balance, while the DCT and collecting duct are involved in the regulation of ion balance and acid-base homeostasis, primarily influenced by hormones like aldosterone and antidiuretic hormone (ADH).
Therefore, the PCT is where a large portion of useful filtrate is reabsorbed, meaning that the statement is accurate. The efficiency of this process ensures that valuable substances are not lost in urine and are retained for the body’s metabolic needs. However, the remainder of the filtrate, which contains waste products like urea, creatinine, and excess ions, continues through the nephron to be excreted as urine.