Atelectasis (/ËÃ¦táµ»ËlÉktÉsáµ»s/ uses combining forms of atel- + ectasis, from Greek: á¼ÏÎµÎ»Î®Ï, incomplete + á¼ÎºÏÎ±ÏÎ¹Ï, extension) is the collapse or closure of a lung resulting in reduced or absent gas exchange.
A single capillary is so small that it allows only one blood cell to flow through it at a time. The capillary walls are also very small, only one cell thick. These thin walls easily allow water, oxygen, carbon dioxide, and other nutrient and waste substances to exchange between blood cells and the surrounding tissue.
Capillaries Tiny blood vessels connecting arteries to veins. These  blood vessels carry oxygen and nutrients to individual cells.  Capillaries are the smallest blood vessels â¦ in the body, and have  walls only one or two cells thick.t is the smallest blood vessels in the body that carries blood cells ,salts & nutrients to be supplied to tissues & organs. It is a minute(nm) tube that permits flow of min â¦ ute solutions/gas in minimum molecular form.