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
Explorers of the Human Body weeks. It was later decided that instead of a hiatus, the program will end the season with thirteen episodes. Super Junior decided to leave the show due to their occupied schedules and busy preparations for their upcoming Asia-wide concert tour, Super Show. However, representatives of the program stated if there is a chance, a second season is considered. "Change", the variety program hosted by Lee Hyo-ri and Shin Dong-yup with Noh Hong-chul, Kangin, Son Ho-young and Min Kyung-hoon as regulars, took over the time slot. Explorers of the Human Body Explorers of the Human Body (Hangul: 인체탐험대; Hanja: 人體探險隊) was