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
History of beliefs about the human body body has in the world. All cultural ideals of the body in the early modern period deal with deficiencies and disorders within a body, commonly told through a male ideal. Ideas of the body in the early modern period form the history of how bodies should be and how to correct the body when something has gone wrong. Therefore, early modern conceptions of the body were not biological as there was not a restrictive biological view of the human body as established by modern science. Conceptions of the body are primarily either eastern, based in China and involving practices such