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Lab4RespiratoryS09 - LAB 4 RESPIRATORY ANATOMY AND...

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2006 Dee U. Silverthorn 42 LAB 4: RESPIRATORY ANATOMY AND SPIROMETRY OUTLINE OF ACTIVITIES I. Sheep lung dissection II. Spirometry A. Standard lung volumes B. Forced expiratory volume (FEV 1 ) C. Maximal voluntary ventilation III. Chemical Control of ventilation OBJECTIVES 1. Identify the major respiratory structures and describe the function of each. 2. Review the histology of the different parts of the conducting system and lungs. 3. Observe or calculate the standard lung volumes and capacities. 4. Measure maximal voluntary ventilation and forced expiratory volume (FEV 1 ), and understand the clinical significance of FEV 1 . 5. Observe changes in plasma CO 2 as the primary drive for ventilation. INTRODUCTION The respiratory system is composed of a gas-exchange organ, the lungs, powered by a pump for moving air in and out. The "pump" in humans consists of the respiratory muscles of the chest wall and the diaphragm. Air is moved in and out of the lungs by pressure differences created through the movement of the rib cage and the diaphragm (P 1 V 1 = P 2 V 2 , from Boyle's Law). When thoracic volume increases, the pressure within the lungs falls below atmospheric pressure, and air flows into the lung ( inspiration ). At the end of inspiration, when respiratory muscles relax, thoracic volume decreases due to elastic recoil of the lungs and chest wall. Decreased volume causes pressure within the lungs to increase and air flows out ( expiration ). The control of ventilation arises in respiratory centers in the medulla of the brain with neurons that connect these centers to the respiratory muscles. Anatomy of the thorax (See Bowden Atlas , pp. 99, 106-108, 126-138) The body cavity known as the thorax is bounded on the sides and top by the bones and muscles of the thoracic cage and on the inferior side by the diaphragm . The chest cavity is subdivided into two pleural cavities and the mediastinum [ mediastinus , in the middle] or midline region. Each pleural cavity consists of a two-layered pleural sac surrounding a lung. The mediastinum contains the heart in its pericardial sac , the major blood vessels, the esophagus, and the trachea. The respiratory muscles of the thoracic cage include the internal and external intercostal muscles (Bowden, p. 128-129), which connect the ribs, and the scalenes (p. 106-108) and sternocleidomastoids (p. 99), which help raise the upper ribs. The sternocleidomastoids attach at their inferior ends to the _____________________________ and the __________________. Their superior ends attach to the _______________________________ (Be as specific as possible in your answer! See Bowden, p. 3 for help.)
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2005 Dee. U. Silverthorn 43 If we call the inferior attachments the origins of the sternocleidomastoids, when the muscles contract, what happens? ___________________________________________________________________________________ The scalenes attach at their superior ends to ______________________________________________ and at their inferior ends to _____________________________________. When the external intercostal muscles, scalenes, and sternocleidomastoids contract, the ribs move up and out. At the same time, the diaphragm contracts and moves downward into the abdomen. As a result of the movement of ribs and diaphragm, the volume of the thoracic cage increases.
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