104 



RESPIRATION 



breathing function is to be really understood. The reader must have 

 in mind the structure of this functional system, from the outer edge 



Fio. 54 



Section of trachea: a, ciliated epithelium of inner wall; 6, basement membrane; c, elastic 

 connective-tissue layer; d, muscular layer; e, gland; /, gland-duct; g, cartilage lying in the 

 fibrous coat. (Bates.) 



of the nostrils to the diaphragm the nasal fossae, larynx, trachea, 

 bronchi, lungs, pleural cavities, thorax, diaphragm, and the nerves 

 which are concerned in the movements of all of these. We can here 



FIG. 55 



Diagram of a lung lobule: a, is placed in a bronchial tube; b, branch of pulmonary artery; 

 from this a branch passes to be distributed to the alveoli of the lobule as seen at d; e, vein 

 which passes on the outside of the lobule to come into relation with the arterial capillaries in 

 the lobule; e, lobar bronchiole; f, infundibulum in which are seen the alveoli. (Bates, modified 

 from Stoehr.) 



mention a few only of the conditions which are the most essential for 

 our purpose. The nose, in man, is very largely a respiratory organ. 



