Earl Dickerson, Jr.
Translocation of Particulate Matter
In Section 9.3, the authors have observed translocation of particular matter. The important notions they have discussed in connection with particulate matter translocation are epithelial barrier, endothelial barrier, and dendritic cells. In the following paper, these notions will be considered with the purpose of identifying their role in the body response to particulate matter exposures.
Epithelial barrier is the unique body mechanism supporting transportation of different chemical substances including nutrients and water into the cells and tissues (Sharma & Tepas, 2010). In addition, it has very important role in prevention of microbial contamination. People with pathologies of epithelial barrier are vulnerable to numerous diseases. Epithelial barrier takes part in translocation of particulate matter in the human body. This translocation occurs when particulate matter deposited in the lungs interacts with epithelial cells (Gurjar, Molina & Ojha, 2010). Translocation of particulate matter through epithelial barrier is performed with the help of inter-epithelial transport leading or dendritic cells. Epithelial barrier is susceptible to the influence of particulate matter. As a result of exposures to particulate matter of various degrees and doses, epithelial barrier in different tissues may lose its functionality partially or completely.
Endothelial barrier is the vessel barrier made of endothelial cells, which covers the inner surface of lymphatic vessels and blood vessels with the purpose of hindering the entrance of leukocytes and blood fluid into tissue (Sharma & Tepas, 2010). Endothelial barrier functions in combination with the basement membrane. Such formation of the inner lining of blood vessel allows immediate delivering of the leukocytes at the sites of inflammation under the effects of cytokine secretion (Malik, Lynch & Cooper, 1989).
Particles Crossing the Endothelial Barrier
Since the endothelial barrier is a porous membrane, particles of specific size may cross it (Sharma & Tepas, 2010). According to the findings made by Sharma and Tepas (2010), particles smaller than 10 μm are able to cross through the endothelial barrier and reach the bloodstream. The structure of the endothelial barrier described in the following quotation explains why such extensive molecules as particulate matter can cross through the membrane into the bloodstream:
“The endothelial monolayer system is constructed by glueing a 13-mm-diameter polycarbonate filter with a pore size of 0.8 ^m to a polystyrene cylinder with a 13-mm exterior diameter and a 9-mm inner diameter. The filters in the assembled chamhers are seeded with endothelial cells at a density of 0.8 X 10' cells/ml (Malik,
Lynch & Cooper, 1989, p. 63).
From the above-mentioned quotation, a conclusion can be made that the endothelial barrier consists of molecules of different sizes, which makes the barrier capable of letting in the substances of different diameter. According to