RespVentPrint15-2

RespVentPrint15-2 - 36 Respiratory Biology The human...

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©2008 Baja Education. All rights reserved. 36 Respiratory Biology The human ventilatory system is a biological pump that generates positive and negative pressure to draw in air and to expel it. Notice that the heart is surrounded by the lungs and that the thorax region has the diaphragm as its lower border and skeletal muscle surrounding it. The system is "air tight" except for the trachea- the only inlet into the lungs for air exchange. Take a deep breath and read on.
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©2008 Baja Education. All rights reserved. 36 Respiratory Biology Figure 1 The Ventilatory system is responsible for bringing air into the lungs and expelling the residual air and metabolic gases from the body. Overall, the system works as a pump. We have already seen how the heart works like a pump and so does the ventilatory system. The heart pumps blood while the ventilatory system pumps air in and out of the body. While the lung is superbly designed for gas exchange, it is also has other functions unrelated to gas exchange owing to its large blood volume that passes through the lung each minute and the immense capillary surface area available for gas exchange. Functions of the lung not directly related to gas exchange are referred to as non-respiratory functions. Some non- respiratory functions of the lung vasculature include its role as a blood filter, blood reservoir, and a metabolizer of circulating substances. The anatomy of the ventilatory system is designed to generate intrathoracic negative and positive pressures for oxygen and carbon dioxide exchange. The major components of the ventilatory system are designed to ultimately transfer the air into the alveoli, the small cavities that are surrounded by pulmonary capillaries carrying partially deoxygenated blood. For air to reach the alveolii, it travels through a number of interesting anatomical routes.
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©2008 Baja Education. All rights reserved. Figure 2 Figure 3. The anatomical divisions of the ventilatory system going from the trachea to the alveoli. Click for Larger Image The route for the air is 1. Nose and mouth 2. pharynx 3. larynx - also known as the voice box 4. trachea 5. bronchi 6. bronchioles 7. alveoli while the route for carbon dioxide is in the opposite direction. "Don't Chew and talk at the Same time!" your Mom would say. A key area in which the ventilatory system and the intestinal system meet is at the pharynx/larynx region. The pharynx is a muscle lined space that connects the nose and mouth to the larynx and esophagus. When you swallow food, it must go from the mouth to pharynx and into the esophagus-not into the Larynx since it would block air going into the lungs. When you swallow food, the larynx is reflexively cut off so that the food goes into the esophagus. This reaction is automatically controlled by the medulla-that part that also
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This note was uploaded on 04/21/2008 for the course BIOL 100 taught by Professor Lee during the Winter '07 term at San Diego State.

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RespVentPrint15-2 - 36 Respiratory Biology The human...

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