144 



ELEMENTARY PHYSIOLOGY 



TRACHEA 



From the above statements we learn that the lungs contain 

 about 230 cubic inches after an ordinary inspiration ; that is, the 

 200 inches of stationary air, together with the 30 inches of tidal 

 air. By taking a very deep inspiration we can add about 100 

 inches to this, bringing the total up to 330 cubic inches, thus 

 inflating the lungs to their full capacity. The term complemental 

 air has been applied to the 100 inches added by the deep in- 

 spiratory effort. 



An adult person at rest breathes about fifteen times a minute ; and, knowing 

 this, we can easily calculate the total quantity of air inspired and expired in 

 a given time. For example, in twenty-four hours this would amount to 

 30 x 15 x 60 x 24 = 648,000 c. ins., or 375 c. ft. 



This quantity, however, is largely increased, and may be more than doubled, 

 by physical exertion. 



Children breathe much more rapidly than adults about thirty times a 

 minute. 



SUMMARY. 



Cartilaginous rings. 

 Fibrous tissue. 



Lined with ciliated epithelium, 

 C-shaped. 



Complete in front. Incomplete behind. 

 Connected by fibrous tissue. 

 Right and left. 



In structure similar to trachea. 

 Rings of cartilage very imperfect. 

 Cartilage disappears in smallest tubes, 

 which terminate in groups of air-cells. 



Thyroid cartilage j ^ arge ' , . 



' 1 Incomplete behind. 



Cricoid cartilage A complete ring. 



Vocal cords. 



Epiglottis Closes the glottis. 



Three lobes. 



Two lobes. 



Air-vessels Bronchial lubes and cells. 



i Pulmonary arteries. 

 Blood-vessels \ Capillaries. 



* Pulmonary veins. 



i 100 residual never 

 200 stationary \ expelled. 



I IOO supplemental. 

 loo residual. 

 loo residual \ ... 

 i<x> supplemental] statlonar y 1 230. 



30 tidal or breathing air } 

 loo residual \ 

 100 supplemental [ 



30 tidal 

 100 complemental) 



LARYNX 



LUNGS 



f Structure 



Rings . . 



Bronchi . 



Bronchial 

 tubes 



Two rings 



Contains . 



Right . . 

 Left . . 



Vessels 



After ordinary expiration. 

 After deep expiration . . 

 After ordinary inspiration 



After deep inspiration . . 





