Atelectasis from the outside (tumor, lymph node, tubercle). Another cause is poor surfactant spreading during inspiration, causing the surface tension to be at its highest which tends to collapse smaller alveoli. Atelectasis may also occur during suction, as along with sputum, air is withdrawn from the lungs. There are several types of atelectasis according to their underlying mechanisms or the distribution of alveolar collapse; resorption, compression, microatelectasis and contraction atelectasis. Relaxation atelectasis (also called passive atelectasis) is when a pleural effusion or a pneumothorax disrupts the contact between the parietal and visceral pleurae. Risk factors associated with increased likelihood of the
Cold and heat adaptations in humans Cold and heat adaptations in humans Cold and heat adaptations in humans are a part of the broad adaptability of "Homo sapiens". Adaptations in humans can be physiological, genetic, or cultural, which allow people to live in a wide variety of climates. There has been a great deal of research done on developmental adjustment, acclimatization, and cultural practices, but less research on genetic adaptations to cold and heat temperatures. The human body always works to remain in homeostasis. One form of homeostasis is thermoregulation. Body temperature varies in every individual, but the average internal temperature is 37.0 °C (98.6 °F).