HUMAN PHYSIOLOGY 



CHAP. 



Complcmental Air 

 About 120 cu. in. 



TMalAir 

 About 30 cu. in. 



Supplemental A ir 

 Ajout 100 cu. in. 



Residual Air 

 About 100 cu. in. 



FIG. 25. Showing lung 

 capacity. 



ingly thin-walled, spherical pouches. 

 On the outer surface of these 

 thin sacs are very small, deli- 

 cate blood capillaries so closely 

 packed together that they really 

 form a little film of blood cover- 

 ing the whole outer surface of 

 the sacs. This film, if spread out, 

 would have an area of over fif- 

 teen hundred square feet. Large 

 surfaces of blood and air are 

 thus brought close together. 



is called the residual air. The 

 total lung capacity is about tJiree 

 hundred and thirty cubic inches 

 for an. average adult. 



The figure to the left shows in 

 a clear way the lung capacity 

 and will help you to remember it. 



52. How Air gets into the Blood. 

 We have just learned how air 

 gets into the lungs and how much 

 the lungs can hold. Let us now 

 see how the air gets from the lungs 

 into the blood, and how the carbon 

 dioxid and other wastes formed 

 in the cells of the tissues get from 

 the blood into the air sacs of the 

 lungs. The air 

 sacs are exceed- 



FlG. 26. Showing the rela- 

 tion of capillaries to air cells 

 in the lungs (Zuppke). 



