The collecting duct is a crucial part of the kidney's nephron, which is responsible for filtering blood and producing urine. It plays a key role in the regulation of water and electrolyte balance in the body. The collecting duct receives urine from multiple nephrons and transports it to the renal pelvis, where it eventually flows into the ureter. In the collecting duct, the reabsorption of water is influenced by the hormone antidiuretic hormone (ADH). When ADH levels are high, more water is reabsorbed, leading to concentrated urine. Conversely, low ADH levels result in less water reabsorption, producing dilute urine.