As the cilia of the mucous membrane cells in the nose move, they push a thin layer of mucus and trapped particles, including dust and other small particles such as bacteria, toward the pharynx, where it is swallowed. In the stomach, gastric juice destroys the bacteria and other microorganisms trapped in the mucus. However, some bacterial spores, including those from the bacterium that causes anthrax, are very small and bypass the hairs and mucus in the nose. Spores are able to reach the lungs, where they release a toxin causing inhalation anthrax, and ultimately cause death.