Buna is a census-designated place in Jasper County, Texas, United States. The population was 2,142 at the 2010 census.
Gas Exchange. Gas exchange is the process by which oxygen and carbon dioxide (the respiratory gases) move in opposite directions across an organism's respiratory membranes, between the air or water of the external environment and the body fluids of the internal environment.
exchange - put in the place of another; switch seemingly equivalent items; the con artist replaced the original with a fake Rembrandt; substitute regular milk with fat-free milk; synonyms can be interchanged without a changing the context's meaning.