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 much on discourse about bodies, rather than on material bodies themselves. Drawing on Mikhail Bakhtin's 1965 "Rabelais and His World", they promoted a more materially orientated direction in the history of the body. The Ebers Papyrus is an Egyptian medical text and is the oldest known record of the human body, dating back to 3000 BC. The Ebers Papyrus describes the body by physical examination and what can be felt. Clinical investigations such as the Pulse, percussion of the body, the recognition of diseased or disordered states. “If thou examinst a swelling of the covering of his belly’s horns above