Māris kļaviņŠ, azamat azizov, JĀnis zaļoksnis environment, pollution, development: the case of uzbekistan

Figure 6.2. 
The structure 
of cell’s membrane.
Figure 6.3. 
Entry of 
substances into the cell 
in case of endocytosis. 

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ENVIRONMENT, POLLUTION, DEVELOPMENT:  THE CASE OF UZBEKISTAN
most cases only lipophilic substances can diffuse through the skin. 
Water-repellent  insecticides,  for  example,  parathion  can  diffuse 
through skin and it has been proved that they may cause poisoning 
of people working with these substances. Even small molecules, for 
example, hydrazine may cause poisoning when taken through the 
skin. Ingestion of substances through lungs is particularly important 
to terrestrial animals, as it is the main pathway for the impact of 
atmo spheric toxicants in form of gas or aerosol. The surface of human 
lungs is as large as 50-100 m
2
 and an intensive gas exchange takes 
place  there.  At  the  same  time,  the  barrier  between  the  circulatory 
system and the air in alveoli can be only a few layers of cells. 
Therefore it can be considered that the absorption of substances 
through inhaling is fast and effective. Gases that dissolve well in the 
water, as a rule, sorb in the upper part of respiratory tract, interacting 
with water in the mucous membranes. The substances that dissolve 
in lipids, in gaseous (vapour) form (for example, chloroform) or small 
molecules (for example, carbon monoxide) in most cases reach alveoli, 
where they desorb and directly enter blood. Sorption of aerosol