i84 BIOLOGY AND HUMAN LIFE 



153. Changes in the blood. While in the capillaries of the 

 various tissues of the body the blood absorbs from the surround- 

 ing lymph (by osmosis) carbon dioxid, urea, and other sub- 

 stances that are present in relatively large proportions (that is, 

 compared to their concentration in the blood plasma) ; and by 

 the same process it loses food materials, salts, oxygen, and fer- 

 ments that are relatively more abundant in the blood than in 

 the surrounding liquids. In certain parts of the body additional 

 changes take place in the composition of the blood. In the 

 intestines, for example, much of the digested food is absorbed 

 into the blood. In the kidneys much of the urea, salts, and 

 other waste substances is taken from the blood. 



DISTRIBUTION OF MATERIAL WITHIN THE BODY 



1. Comparison of one-celled organisms with many-celled organisms 



regarding relation to environment 

 Income ; outgo 



2. Comparison of plants and animals regarding means of distributing 



material 

 The two kinds of sap in plants and the two kinds of vessels 

 The blood in animals 



3. Composition of mammahan blood (including human blood) 



Plasma Corpuscles 



Water White 



Dissolved nutrients Eating cells (phagocytes) 



Dissolved salts Moving cells 



Dissolved gases Irritable cells 



Ferments (hormones) Red 



Fibrinogen Gas carriers (hemoglobin) 



4. Clotting of blood 



Fibrin formation 



Conditions of clotting How it takes place 



Cut or bruise of capillaries Possible uses to organism 



(Some diseased conditions) Remaining fluid (serum) 



5. The lymph 



Its character 

 Its composition 

 Its functions 



