BIOA02H3 Lecture Notes - Mount Everest, Partial Pressure, Cellular Respiration
16 Jun 2011
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The respiratory gases that animals must exchange are oxygen (o2) and carbon dioxide (co2). Cells need to obtain o2 from the environment to produce an adequate supply of. Co2 is an end product of cellular respiration, and it must be removed from the body to prevent toxic effects. Diffusion is the only means by which respiratory gases are exchanged between the internal body fluids of an animal and the outside medium (air or water). There are no active transport mechanisms to move respiratory gases across biological membranes. Because diffusion is a physical process, knowing the physical factors that influence rates of diffusion helps us understand the diverse adaptations of gas exchange systems. Because diffusion results from the random motion of molecules, the net movement of a molecule is always down its concentration gradient. One way biologists express the concentrations of different gases in a mixture is by the partial pressures of those gases.
