20_Respiratory - Computer 20 Respiratory Response to...

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Human Physiology with Vernier 20 - 1 Computer 20 Respiratory Response to Physiologic Challenges The respiratory cycle of inspiration and expiration is controlled by complex mechanisms involving neurons in the cerebral cortex, brain stem, and peripheral nervous system, as well as central and peripheral receptors. These receptors respond to a variety of stimuli including chemicals and pressure. Central respiratory control ( respiratory drive ) occurs in the pons and medulla, which respond directly to chemical influences. Other input is received from stretch receptors in the lungs and chemoreceptors located in the carotid and aortic bodies (see Figure 1). The chemoreceptors respond most sensitively and rapidly to carbon dioxide but also to oxygen and pH (acidity). Constant adjustments in the respiratory cycle occur throughout the day to allow gas exchange in the lungs to maintain a steady level of CO 2 in the bloodstream. An increase in the CO 2 level stimulates breathing, while a decrease inhibits it. If the deviation from the “set point” is large enough you may experience shortness of breath. The oxygen level can also influence the respiratory cycle, but larger deviations are required before its influence is felt. At rest, the average adult male produces approximately 200 mL of CO 2 each minute, but this may increase to over 2000 mL with exercise or heavy work. Hyperventilation lowers CO 2 levels due to an increased opportunity for gas exchange in the lungs. Holding one’s breath or re- breathing air (such as breathing into a paper bag) raises CO 2 levels because there is less opportunity for gas exchange. In this experiment, you will alter CO 2 levels by holding your breath ( hypoventilation ), rapid breathing ( hyperventilation ), and exercise. You will compare the respiratory rate, tidal volume, and minute ventilation that result from each physiologic challenge to homeostasis. Important: Do not attempt this experiment if you are currently suffering from a respiratory ailment such as the cold or flu. OBJECTIVES In this experiment, you will Obtain graphical representation of normal tidal volume. Compare tidal volumes generated by various physiologic challenges. Correlate your findings with real-life situations. Figure 1
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20 - 2 Human Physiology with Vernier Computer 20 MATERIALS computer Vernier computer interface disposable bacterial filter Logger Pro nose clip Vernier Spirometer PROCEDURE Part I Tidal Volume Response to Breath Holding Start computer and plug in Vernier labpro into outlet. Connect the Spirometer into CH1 (on the front left side) on the labpro using the white square plug. Use the USB cable to connect the labpro to the computer (The small, square connector plugs into the USB port on the right side of the labpro. The wide connector end plugs into the USB port on the left side of the laptop.) Launch the Logger Pro software using the icon on the quick launch toolbar on the bottom of the laptop screen. From the ‘File’ menu, ‘Open’ the file “20 Respiratory
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20_Respiratory - Computer 20 Respiratory Response to...

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