Trachea Diffusion of oxygen and carbon dioxide takes place across the walls of the smallest tubes, called tracheoles, which penetrate tissues and even indent individual cells. Gas may be conducted through the respiratory system by means of active ventilation or passive diffusion. Unlike vertebrates, insects do not generally carry oxygen in their haemolymph. This is one of the factors that may limit their size. A tracheal tube may contain ridge-like circumferential rings of taenidia in various geometries such as loops or helices. Taenidia provide strength and flexibility to the trachea. In the head, thorax, or abdomen, tracheae may also be connected
101 Things Removed from the Human Body from their body survived. This program also aired in the USA on the Discovery network's "The Learning Channel" in October 2007. The program contains stories, including a man having a uterus and a man with a teratoma, a type of large tumor. The large jaw tumor segment featured the work Mercy Ships, who have operated floating hospital ships in impoverished areas around the world. 101 Things Removed from the Human Body 101 Things Removed from the Human Body and 101 More Things Removed from the Human Body is a British "shockumentary" series directed by Eric Schotz, which is narrated by