Atelectasis Leakage of air into the pleural cavity (pneumothorax) also leads to compression atelectasis. It occurs when either local or generalized fibrotic changes in the lung or pleura hamper expansion and increase elastic recoil during expiration. Causes include granulomatous disease, necrotising pneumonia and radiation fibrosis. Chronic atelectasis may take one of two forms—middle lobe syndrome or rounded atelectasis. In right middle lobe syndrome, the middle lobe of the right lung contracts, usually because of pressure on the bronchus from enlarged lymph glands and occasionally a tumor. The blocked, contracted lung may develop pneumonia that fails to resolve completely and leads to
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