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.
Gas exchange is important as it is the transfer of oxygen from the surroundings to individual cells in the body, required by the cells for respiration.This process produces energy, essential for the organisms survival.hese provide a very  large surface area for the exchange of respiratory gases by  diffusion betweent he alveoli and the blood in the capillaries.   Gas exchange occurs in two stages of ventillation, called  inhilation and exhilation.