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CHAPTER FIVE THE RESPIRATORY SYSTEM Respiration is the process in which the respiratory system pulls oxygen (O 2 ) from the atmosphere and supplies it to the cells in all parts of the body. The cells eliminate the residue in the form of carbon dioxide (CO 2 ). The exchange of these gases means that the body has successfully provided oxygen throughout the system. During external respiration (breathing), oxygen enters the lungs (inspiration) and is transported to the capillaries. The cells use the oxygen and then pass carbon dioxide back into the lungs to be expelled from the body (expiration). During internal respiration, the body cells remove oxygen from the blood and gives back carbon dioxide, which is then transported back to the lungs. Inhalation brings air into the lungs while exhalation expels air from the lungs. Normal respiration occurs every 3-5 seconds. Respiration is achieved through the mouth, nose, trachea, lungs, and diaphragm. Oxygen enters the respiratory system through the mouth and the nose. The oxygen then passes through the larynx (where speech sounds are produced) and the trachea which is a tube that enters the chest cavity. In the chest cavity, the trachea splits into two smaller tubes called the bronchi. Each bronchus then divides again forming the bronchial tubes. The bronchial tubes lead directly into the lungs where they divide into many smaller tubes which connect to tiny sacs called alveoli. The average adult's lungs contain about 600 million of these spongy, air-filled sacs that are surrounded by capillaries. The inhaled oxygen passes into the alveoli and then diffuses through the capillaries into the arterial blood. Meanwhile, the waste-rich blood from the veins releases its carbon dioxide into the alveoli. The carbon dioxide follows the same path out of the lungs when you exhale. The diaphragm's job is to help pump the carbon dioxide out of the lungs and pull the oxygen into the lungs. The diaphragm is a sheet of muscles that lies across the bottom of the chest cavity. As the diaphragm contracts and relaxes, breathing takes place. When the diaphragm contracts, oxygen is pulled into the lungs. When the diaphragm relaxes, carbon dioxide is pumped out of the lungs. ( ) ORGANS OF THE RESPIRATORY SYSTEM ORGAN DEFINITION nose lined with mucous membrane and fine hairs. Acts as a filter to moisten and warm the entering air nasal septum partition separating the right and left nasal cavities paranasal sinuses air cavities within the cranial bones that open into the nasal cavities 1
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pharynx (throat) serves as a food and air passageway. (Air enters from the nasal cavities and passes through the pharynx to the larynx. Food enters the pharynx from the mouth and passes through
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This note was uploaded on 11/22/2010 for the course HSC 2531 taught by Professor Chancey during the Spring '10 term at Santa Fe College.

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