lecturenotes28-35

lecturenotes28-35 - Lecture 28: Respiratory Physiology I...

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Lecture 28: Respiratory Physiology I Reading: ch 13, section: intro, mechanics, pgs 451-463 (pgs 459-471, if using 5 th edition) Respiration - Respiration, the process of obtaining O 2 from the environment and eliminating CO 2 from the body, can be subdivided into 2 separate processes (Figure 13-1) . internal respiration - this refers to the intracellular metabolic processes that take place within mitochondria, which use O 2 and produce CO 2 during the derivation of energy from nutrient molecules. external respiration - this refers to the entire sequence of events involved in exchanging O 2 and CO 2 between the environment and the cells of the body. It is composed of four subprocesses, the first two of which are accomplished by the respiratory system . 1) breathing - the alternate movement of air in and out of the lungs to exchange gas between the environment and the alveoli . 2) alveolar gas exchange - exchange of O 2 and CO 2 between gas in the alveoli and blood in the pulmonary capillaries 3) gas transport - the transport of O 2 and CO 2 by the blood from the lungs to the tissues of the body 4) blood gas exchange - the exchange of O 2 and CO 2 between the blood and the tissues Respiratory System - the system responsible for the first two stages of external respiration (Figure 13-2) . Respiratory Airways - these are the tubes that carry air between the atmosphere and the alveoli. nasal passages - nose pharynx - common passageway for the lungs and the stomach
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larynx - voice box located at the entrance to the trachea trachea - tube through which air is conducted to the lungs bronchi - division of the trachea into two main branches bronchioles - small branches of the respiratory airway alveoli - tiny, air-filled chambers (~300 µ m dia) within the lungs that serve as the site for the exchange of O 2 and CO 2 with the blood (Figure 13-4) . They form into grape-like clusters at the terminal branches of bronchioles, and their walls are formed by a single layer of flattened type I cells . They are surrounded by a dense meshwork of pulmonary capillaries that lie in close proximity. The large number and high density of alveoli greatly increases the surface area for contact between the inspired air and the blood. The close contact between the alveoli and the pulmonary capillaries facilitates the diffusion of gases down their concentration gradients. The alveoli also contain type II cells that secrete a pulmonary surfactant that acts to reduce the surface tension of the water inside the alveoli. Lungs - a pair of organs, housed within the thoracic cavity , consisting of the lower portion of the respiratory airways, the pulmonary circulation, and connective tissue. Pleural Sacs - a pair of thin, fluid-filled, membranes that enclose the lungs. The space between the pair of membranes is referred to as the pleural cavity (Figure 13-5) . Respiratory Mechanics
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This note was uploaded on 05/02/2008 for the course NPB 101 taught by Professor Fuller,charles/goldberg,jack during the Winter '08 term at UC Davis.

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lecturenotes28-35 - Lecture 28: Respiratory Physiology I...

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