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 observed in Eskimo, who have shorter limbs than other people and are laterally built. Origins of heat and cold adaptations can be explained by climatic adaptation. This can be traced back to the body’s responses to differing environments immediately after leaving Africa, such as extreme cold, humid heat, desert conditions, and high altitudes. Ambient air temperature affects how much energy investment the human body must make. The temperature that requires the least amount of energy investment is 21 °C (69.8 °F). The body controls its temperature through the hypothalamus. Thermoreceptors in the skin send signals to the hypothalamus, which indicate