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The Respiratory System Study Guide (page 2)

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Updated on Sep 22, 2011

What Happens in the Body's Cells?

Once the newly oxygenated blood leaves the lungs, it is distributed throughout the body to every cell. Each cell engages in cellular respiration (metabolism), thus using up oxygen and producing carbon dioxide. Inside the cell is thus a high concentration of carbon dioxide, but in the blood and surrounding fluid outside the cell, the concentration of carbon dioxide is low. So, again, a gas exchange occurs where oxygen flows from a high concentration outside the cell to the low-concentration side on the inside of the cell. Carbon dioxide flows in the opposite direction. The blood is now high in carbon dioxide and makes its way back to the lungs for more gas exchange with atmospheric air that has been breathed in and conducted to the lungs.

Gas Exchange in Plants

Plants exchange gas as well. Single-celled plants, like their animal counterparts, simply exchange gases through the cell membranes. Multicellular plants must develop specialized tissues. The plant uses pores on the leaf surface, called stomata, to exchange gases with the atmosphere.

In Short

The word respiration is used in two different but related ways in biology. In one sense, respiration means the act of bringing air into the lungs and expelling waste gases. We call this form of respiration breathing. However, the chemical reactions of metabolism partly contain a set of reactions that use enzymes and oxygen to burn food molecules and release the energy of their bonds. This process is more specifically known as cellular aerobic respiration (or anaerobic when no oxygen is present). All organisms, even single-celled ones, must perform cellular respiration (either aerobically or anaerobically) during metabolism to obtain necessary energy to support life functions.

The vertebrate respiratory system contains two parts, the part that conducts air and the gas exchange portion. The trachea, bronchus, and brochials form the tube that conducts air from the mouth and nose into the lungs. The alveoli are the site of gas exchange within the lungs.

Plants have a gas exchange process as well. Singlecelled plants, like their animal counterparts, simply exchange gases through the cell membranes. Multicellular plants must develop specialized tissues, and the plants use pores on the leaf surface, called stomata, to exchange gases with the atmosphere.

Practice problems of this concept can be found at: The Respiratory System Practice Questions

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