Anterior view of the lungs and heart. Labels: 1, heart; 2, inferior vena cava; 3, superior vena cava; 4, right innominate vein; 5, left innominate vein; 6, jugular vein; 7, subclavian vein; 8, arch of aorta; 8', subclavian artery; 9, left pulmonary artery; 9', 9', carotid artery; 10, trachea; 11, left bronchus; 12, ramifications of right bronchus exposed in upper lobe of right lung; 13, 14, middle lobe; 15, lower lobe; 16, upper lobe of left lung; 17, lower lobe of left lung.

Anterior View of the Lungs and Heart

Anterior view of the lungs and heart. Labels: 1, heart; 2, inferior vena cava; 3, superior vena cava;…

"The respiratory mechanism consists of the lungs, a series of minute air chambers with a network of capillaries in the wall, the air passages from the air chambers of the lngs to the outer air, and the chest walls with their muscles, which act like bellows and change the ai r in the lungs. Let us begin with the air passages. There are first the nose and mouth; these join the upper part of the gullet, known as the pharynx. From the pharnyx arises the windpipe (trachea); this passes through the voice box (larynx) into the chest cavity; there it divides into two passages (the bronchi); the bronchi go on dividing again and again, generally into two; the ultimate divisions (the bronchioles) open into clusters of air chambers."—(Charles Leonard-Stuart, 1911)

Respiratory Mechanism

"The respiratory mechanism consists of the lungs, a series of minute air chambers with a network of…