Trachea emergency situation, and this is a cricothyrotomy. Tracheal agenesis, is a rare birth defect in which the trachea fails to develop. The defect is usually fatal though sometimes surgical intervention has been successful. A tracheoesophageal fistula is a congenital defect in which the trachea and esophagus are abnormally connected. Sometimes as an anatomical variation one or more of the tracheal rings are completely formed. These "O" rings are smaller than the normal C-shaped and can cause narrowing of the trachea resulting in breathing difficulties. An operation called a "slide tracheoplasty" can be performed which opens up the rings and rejoins
Effect of spaceflight on the human body Effect of spaceflight on the human body Venturing into the environment of space can have negative effects on the human body. Significant adverse effects of long-term weightlessness include muscle atrophy and deterioration of the skeleton (spaceflight osteopenia). Other significant effects include a slowing of cardiovascular system functions, decreased production of red blood cells, balance disorders, eyesight disorders and a weakening of the immune system. Additional symptoms include fluid redistribution (causing the "moon-face" appearance typical in pictures of astronauts experiencing weightlessness), loss of body mass, nasal congestion, sleep disturbance, and excess flatulence. The engineering problems associated with leaving Earth and developing