The excretory system in humans primarily removes waste products generated from metabolism. It consists of kidneys, ureters, the bladder, and the urethra. The kidneys filter blood, creating urine, which contains toxins and excess ions. Urine flows from the kidneys through the ureters to the bladder, where it is stored until elimination through the urethra. This system is vital for maintaining the body's internal balance of water and salts, known as homeostasis.