How do different animals ventilate their lungs/spiracles?
(mammals, birds, reptiles, frogs, invertebrates) The functional anatomy of the lungs and associated structures vary considerably among animals in the mechanism of lung/spiracle ventilation. Mammals The lungs of mammals are elastic, multi-chambered bags, which open to the exterior through a single tube, called the trachea. The lungs are suspended within the pleural cavity. The ribs and the diaphragm form the walls of the pleural cavity, which are referred to as the thoracic cage. The thoracic cage mostly consists of the lungs, but between the lungs and the thoracic walls there is a low-volume of pleural space sealed and fluid filled. During normal breathing, the thoracic cage expands and contracts by a series of skeletal muscles, the diaphragm, and the external and internal intercostal muscles. The respiratory center within the medulla oblongata controls the contractions of these muscles through the activity of motor neurons. During inhalation, the volume of the thorax increases due to
