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

particles depends on their dimensions. If coarser aerosols (<20 µm) 
mostly are detained in the upper part of respiratory tract, the 
smaller aerosols (>10 µm) can penetrate the alveoli and from there 
they are eliminated very slowly. The aerosol particles whose size is 
less  than  1  µm  can  be  assimilated  as  a  result  of  endocytosis,  and 
be detained in respiratory system for a long time. Especially small 
aerosol particles can get directly in circulatory system. It has been 
proven that uranium dioxide particles (<3 µm) or lead aerosols after 
inhalation can enter the circulatory system.
After the substances have adsorbed, they enter into the general 
circulation  system  of  a  bodys.  After  the  absorption  of  substances, 
their  distribution  in  the  organism  takes  place.  After  crossing  the 
«barriers» of the organism (skin, lungs or gastrointestinal tract) the 
sub stances enter the intercellular fluid, which encompasses the cells 
and comprises about 15% of the total body weight. Other body fluids 
are  the  cytoplasm,  representing  about  40%,  and  blood  plasma  – 
about 8% of the weight. From the intercellular fluid the substances 
can enter the tissues, blood capillaries and the circulatory system, 
as well as the lymphatic system. Substances, which enter the circu-
la tory system, are quickly dispersed in the organism, unlike the 
lymphatic system, in which the speed of movement is significantly 
slower.
Metabolism (metabolic) products are called metabolites. Cata-
bolism is the splitting of larger molecules, mainly as a result of 
hydro lysis and oxidation reactions, through the release and accumu-
lation  of  energy.  Anabolism  is  the  synthesis  of  molecules  specific 
to organism from low molecular weight fragments, and during this 
When substances enter 
the organism, a number 
of different reactions 
take place with them, 
which generally are 
defined as metabolism, 
which consists of two