Is a alveoli part of the excretory system?

No, alveoli are not part of the excretory system. They are small air sacs in the lungs that facilitate gas exchange, allowing oxygen to enter the bloodstream and carbon dioxide to be expelled from the body. The excretory system, on the other hand, is responsible for eliminating waste products from the body, primarily through the kidneys, ureters, bladder, and urethra.