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 Atelectasis may also occur during suction, as along with sputum, air is withdrawn from the lungs.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
Neoteny in humans body is indicated by glabrousness (hairless body). Neoteny of the genitals is marked by the absence of a baculum (penis bone); the presence of a hymen; and the forward-facing vagina. Neoteny in humans is further indicated by the limbs and body posture, with the limbs proportionately short compared to torso length; longer leg than arm length; the structure of the foot; and the upright stance. Humans also retain a plasticity of behavior that is generally found among animals only in the young. The emphasis on learned, rather than inherited, behavior requires the human brain to remain receptive much longer. These