The primary function of the excretory system is to remove waste products and excess substances from the body while maintaining a balance of water, salts, and other vital components. This system primarily includes the kidneys, ureters, bladder, and urethra. The kidneys filter blood to create urine, which contains waste materials such as urea, creatinine, and various ions. This urine is then transported via the ureters to the bladder for storage before being expelled from the body through the urethra. Proper functioning of the excretory system is essential for overall health and homeostasis.