EXERCISE 77 DEMONSTRATION 



The blood carries not only food and wastes but also the gases involved in respiration. 



Problem. How do gases of the air affect the blood? 



What to use. The blood from which the fibrin has been removed, 1 in two beakers ; oxygen ; carbon 



txid ; rubber tube ; glass tube. 

 What to do. Connect the glass tube by means of the rubber tube to the tank or generator for supply 

 of carbon dioxid. Pass a current of the gas through the blood (A} by placing the glass tube in the blood. 

 After noting the action for a few moments pass oxygen through the blood in the second beaker (B}. 

 After comparing effects reverse the procedure ; that is, pass oxygen through A, and carbon dioxid 

 through B. 



Record. Describe the appearance produced by oxygen and the appearance produced by carbon 

 dioxid. Tell what happened to the appearance of oxygenated blood that was treated with carbon dioxid 

 and what happened when this was again treated with oxygen. 



NOTE. Blood contains an iron-bearing protein in the red corpuscles called hemoglobin, which has a decided affinity for 

 various gases and forms with oxygen a chemical compound called oxyhemoglobin. In the presence of carbon dioxid, hemo- 

 globin releases oxygen and takes up carbon dioxid. 



1 Whole blood may be used in which clotting has been prevented by the addition of one part sodium oxalate solution (3.8 %) 

 to nine parts blood. 



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