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 to warm them during the colder nights . The only mechanism the human body has to cool itself is by sweat evaporation. Sweating occurs when the ambient air temperatures is above 28 °C (82 °F) and the body fails to return to the normal internal temperature. The evaporation of the sweat helps cool the blood beneath the skin. It is limited by the amount of water available in the body, which can cause dehydration. Humans adapted to heat early on. In Africa, the climate selected for traits that helped us stay cool. Also, we had physiological mechanisms that reduced the