Correct Option
The correct option is Both 1 and 2.
Explanation
Urine formation involves three main processes: glomerular filtration, reabsorption, and secretion. The kidneys filter a large volume of blood plasma to remove metabolic wastes while retaining essential nutrients and water through selective reabsorption.
Statement-wise Analysis
- Statement 1 is Correct: The first step in urine formation is the filtration of blood, which is carried out by the glomerulus. The Glomerular Filtration Rate (GFR) in a healthy individual is approximately 125 ml/minute. This amounts to roughly 180 liters per day.
- Statement 2 is Correct: Although 180 liters of filtrate are formed daily, the volume of urine actually released is only about 1.5 liters. This significant reduction occurs because nearly 99% of the filtrate is reabsorbed by the renal tubules (Proximal Convoluted Tubule, Loop of Henle, Distal Convoluted Tubule, and Collecting Duct) back into the blood.
Key Takeaway
Key Takeaway: The kidneys possess a highly efficient reabsorption mechanism, reclaiming approximately 99% of the initial glomerular filtrate (180 L/day), resulting in a final urine output of only 1-1.5 L/day.