Lungs (An Overview)

Air, which is inhaled through the mouth and nasal passages, travels through the windpipe or "trachea" into two main air passages. These divide into smaller branches which separate into even smaller "twigs" like an upside-down tree. The respiratory system is mainly contained in two lungs. The little air sacs at the end of the twigs comprise the fruit of the tree, and through its thin walls gasses pass into and out of the blood. The right lung is made up of three compartments, each of which contain a branch and each of which stems off into smaller "twigs," which hold the air sacs (or "fruit" of the tree) that process the oxygen in the air to be released into the blood and expel carbon dioxide, which is exhaled through the nose and mouth. The left lung cavity contains only two sections (each with its own branches, twigs and fruit) and encloses the heart, which processes the oxygenated blood and returns deoxygenated blood into the lungs for exhalation. Breathing is an automatic process which comes from the brain stem and is so strong a force that the involuntary reflexes will not allow us to stop breathing for any length of time. The passageways in the respiratory system are lined with various types of epithelia to prepare the air properly for utilization and with hair-like fibers called cilia that move in a wave-like motion to sweep debris out of the lungs for expulsion. The women in ancient Greece and Rome wore corsets of linen to restrain their figures. The female waistline has been moved up and down over the passage of time, but this became a real health hazard when whalebone corsets came into use during the last part of the 19th and early part of the 20th centuries, because they constricted the vital organs in the body - especially those of the respiratory and digestive systems. Women with "wasp-like" waists fainted so often that those who were well-off purchased "fainting" couches; and when a woman "swooned," the cry, "Cut her laces!" often allowed her enough air to recover.