Virtually all life on earth is based on the oxidation of carbon compounds during the process of respiration. One of the products of oxidation is the gas carbon dioxide. Living organisms must take in oxygen and eliminate carbon dioxide. Single celled organisms, such as an amoeba, can extract oxygen directly from the water surrounding them, through an outer permeable membrane; carbon dioxide is eliminated in the same way. They can do this since their outer surface area is great, relative to their volume. With larger animals, however, more complex mechanisms are needed to extract oxygen from air or water. “Breathing and Respiration” is part of the “Mechanics of Life” series, an introduction to human biology and physiology tailored to the middle-school audience. Humans and other vertebrates are the most prominent animals on earth. There is a great variety among them, but they share certain characteristics that have made them dominant. The vertebrate organism can be viewed as a machine that is the sum of a number of independent yet interacting systems and sub-systems. The “Mechanics of Life” video series describes and illuminates five of the principal systems.
11 minutes • Color