Final answer:
The first section of the nephron loop that the glomerular filtrate encounters is the proximal convoluted tubule, where significant reabsorption of solutes occurs.
Step-by-step explanation:
The first section of the nephron loop glomerular filtrate encounters is the proximal convoluted tubule (PCT). Urine formation begins with the process of glomerular filtration, where water and solutes are filtered out of the blood and into Bowman's capsule.
This filtrate then passes into the proximal end of the renal tubule. In the PCT, a significant amount of solutes get reabsorbed by tubular reabsorption, which is essential for regulating the content and volume of urine. Filtrate then continues through the nephron, passing through the loop of Henle, the distal convoluted tubule, and finally the collecting ducts that lead to the renal papilla and ureter.