Atelectasis is composed of 78% nitrogen and 21% oxygen. Since oxygen is exchanged at the alveoli-capillary membrane, nitrogen is a major component for the alveoli's state of inflation. If a large volume of nitrogen in the lungs is replaced with oxygen, the oxygen may subsequently be absorbed into the blood, reducing the volume of the alveoli, resulting in a form of alveolar collapse known as absorption atelectasis. It is usually associated with accumulation of blood, fluid, or air within the pleural cavity, which mechanically collapses the lung. This is a frequent occurrence with pleural effusion, caused by congestive heart failure (CHF).
Cold and heat adaptations in humans with aborigines having a much lower sweat rate than whites. Social adaptations enabled early modern humans to occupy environments with temperatures that were drastically different from that of Africa. (Potts 1998). Culture enabled humans to expand their range to areas that would otherwise be uninhabitable. Humans have been able to occupy areas of extreme cold through clothing, buildings, and manipulation of fire. Furnaces have further enabled the occupation of cold environments. Australian aborigines only wear genital coverings for clothes, but studies have shown that the warmth from the fires they build is enough to keep the body from fighting heat