Biology: Three kinds of respiration
Tutoring Biology 12, you cover the cardiovascular system. The biology tutor discusses the gas exchange aspect.
People commonly associate respiration with breathing. However, from a biology point of view, the meanings are different. Breathing is the physical process of bringing fresh air into the lungs and then pushing out “used” air. Respiration means gas exchange.
There are three kinds of respiration: external, internal, and cellular.
External respiration is the one everyone thinks of: in the lungs, the blood drops off its carbon dioxide and picks up oxygen.
Internal respiration happens in the tissues. Blood drops off its oxygen to the tissue fluid (whence it reaches the cells), while collecting the carbon dioxide that the cells are constantly producing.
Cellular respiration happens inside the cell, in the mitochondria. It is the chemical process of burning glucose with oxygen to produce energy, carbon dioxide, and water. (The carbon dioxide produced by cellular respiration is, of course, what you breathe out when you’re running:))
Each of these aspects of respiration needs more discussion, but this is a good starting point. Drop in again for more about them:)
Source: Mader, Sylvia S. Inquiry into Life, 11th edition. New York: McGraw-Hill, 2006
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