The human respiratory system is one of the chief and most important which is very instrumental for survival. Prime function of the respiratory system is breathing. Inhaling oxygen and exhaling carbon dioxide is all that takes plays by function of the respiratory organs. Breathing is a process by which oxygen in the air is brought in to the lungs and further in to close contact with blood. The blood absorbs the oxygen and carries to all parts of the body. Simultaneously blood gives up waste matter in form of carbon dioxide through lungs to carry out by breath-out. Hence the respiratory system keeps on working without any rest and relaxation there by keeping living being in life and activity. The rate of breathing or cellular respiration varies with level of activity not only physical but also mental. Main organ of the respiratory system can be stated as below: 1. Nostrils
2. Pharynx Nasal and Oral
During breathing air enters through the nostrils, nasopharynx, and oral pharynx then through the glottis in to the trachea and further right and left bronchi and Lung alveoli. Only in the alveoli actual exchange of oxygen and carbon dioxide takes place.
During inspiration (inhaling),
◦ The external intercostal muscles contract, lifting the ribs up and out. ◦ The diaphragm contracts, drawing it down .
During expiration (exhaling), these processes are reversed and the natural elasticity of the lungs returns them to their normal volume. At rest, we breathe 15-18 times a minute exchanging about 500 ml of air. In more vigorous expiration, ◦ The internal intercostal muscles draw the ribs down and inward ◦ The wall of the abdomen contracts pushing the stomach and liver upward. Under these conditions, an average adult male can flush his lungs with about 4 liters of air at each breath. The below table shows what happens to the composition of air when it reaches the alveoli. Some of the oxygen dissolves in the...
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