54 
LABORATORY EXERCISES 
EXERCISE 57 
THE HUMAN RESPIRATORY ORGANS 
Use a manikin or skeleton if possible. If these are not available, 
use a chart or the diagram in the text. 
I. The Nasal Passages. Review the position of the throat and 
nasal passages and their relation to each other. (See Exercise 54.) 
II. The Lungs. What are the position, number, and shape of 
the lungs? What is their relation to the chest wall? To the dia¬ 
phragm? Find the position of one of your collar-bones. What is 
the relation of the apex of the lung to this bone? Find the lower 
ribs. Note the relative positions of the lungs and the lower 
ribs. Study the relation of the trachea to the lungs. Note the 
distribution of its branches to the parts of the lungs. What is the 
use of the trachea? Where does air enter the lungs? Note 
the distribution of the blood vessels of the lungs. Why is this 
significant? 
EXERCISE 58 
AIR IN THE LUNGS 
I. Note and estimate the amount of air which is drawn in and 
which is exhaled in each breath. Breathe naturally. The air 
which is inhaled under this condition is tidal air. After taking in 
the tidal air, draw in as much more air as you can. This extra air 
is complciueutal air. Compare the quantity of the two volumes. 
After-breathing out the tidal air, force out as much more as you 
can. This last is reserve air. Compare the amount of this with 
the other volumes. Residual air, about equal in quantity to the 
reserve air, remains in the lungs and cannot be forced out. 
The diagram in the text (see Waggoner, Fig. 153) represents the 
relative volumes of air which are used by an adult of average size. 
II. What part of the lung capacity is taken up by the tidal air? 
What portion of the lungs is filled with fresh air in quiet breathing? 
