What role does the collecting duct play in the urinary system?

The collecting duct plays a crucial role in the final concentration of urine. As urine passes through the collecting duct, the body has the opportunity to reabsorb water from the filtrate, guided primarily by the hormone vasopressin (also known as antidiuretic hormone). This process fine-tunes the concentration of the urine based on the body’s hydration status. When the body is dehydrated, more water is reabsorbed, resulting in concentrated urine. Conversely, when the body is well-hydrated, less water is reabsorbed, resulting in dilute urine. This regulation enhances the kidneys' ability to maintain homeostasis in fluid balance and electrolytes for the organism.