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 Atelectasis may also occur during suction, as along with sputum, air is withdrawn from the lungs.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
Body language of dogs tail, the ears, and the head/body. Tail-wagging is a common tail movement used by dogs to communicate. Additionally, ear flattening or heightening are typical movements made using the ears. In terms of the head/body, it is of interest to study turning of the head, as well as the overall posture of the dog. Because dogs communicate differently than humans, it is more difficult for humans to interpret their emotional states. By focusing on the combinations of motions made by dogs, and studying the aftermath of such sequences, humans are able to attribute different emotional states (i.e., contentment, fear, or aggression)