204 APPLIED PHYSIOLOGY 



8. Artificial respiration can be performed by alternately 

 pulling the arms above the head and compressing 

 them against the chest about twenty times a minute. 



DEMONSTRATIONS 



81. Each pupil can notice the different movements of his own 

 breathing. At will he can change from abdominal breathing to thoracic 

 breathing, or can use all of the muscles of the chest in taking a very 

 deep inspiration. A tape measure passed around the body just under 

 the armpits will show how the chest increases in size with each inspira- 

 tion and diminishes with expiration. 



82. A small animal should be killed and its chest opened so as to 

 show the lungs and heart in place. Notice the shining pleura, and 

 that at the back part of the chest it leaves the chest wall and covers 

 the lungs. Notice the position of the ribs and diaphragm, and the ar- 

 rangement and direction of their muscle fibers. (See demonstration 35.) 



83. In a recently killed cat or dog the diaphragm can be made to 

 contract by irritation of the nerve called the phrenic nerve, which con- 

 veys orders for motion from the respiratory center to the diaphragm. 

 There are two nerves, one of which enters the diaphragm near the 

 middle of each side of the arch. Remove the lungs carefully. Then 

 the site of the nerve can be recognized by a slight roughness in the 

 otherwise smooth pleural covering. Pricking or pinching this point 

 will cause a contraction of the diaphragm. (See demonstration 35.) 



84. Kill a frog by placing it in a tight jar with a few drops of chloro- 

 form. Open its chest and abdomen. Insert a small pointed glass tube 

 into its trachea. The slitlike opening can be found upon the back of 

 the tongue. Blow through the tube to inflate the lungs, and at once tie 

 a string tightly around their base. Remove the lungs and let them dry. 

 Notice the partitions like the cells in a honeycomb, extending a little 

 way into the central cavity. Explain that a man's lung is like a col- 

 lection of tiny frog's lungs. (See illustration on page 196.) 



85. Examine a prepared microscopic specimen of a lung and of 

 the trachea and bronchi. Notice the ciliated epithelium in the trachea 

 and bronchi. Notice that the walls of the air sacs form an irregular 

 network inclosing the large spaces of the air sacs. The specimen 

 will probably show a small bronchus. Notice its thick walls containing 

 some muscular tissue and possibly some cartilage. 



