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BIPN102 M1FA09 Key


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BIPN 102, MAMMALIAN PHYSIOLOGY II LAST NAME:________ANSWER KEY________ Fall 2009 1st MIDTERM EXAM I.D. #______________ October 23, 2009 1 1. (16 points) Number the sequence of events for inspiration. (points allotted up to the first wrong answer). 8 a. Air flows into the lungs 2 b. Diaphragm contracts 6 c. Alveolar volume increases 5 d. Transpulmonary pressure increases 3 e. Intrapleural volume increases 7 f. Alveolar pressure decreases 1 g. Action potentials are conducted in the phrenic nerve 4 h. Intrapleural pressure decreases 2. (17 points) The following is a list of P IP and P A values at sea level. What is happening? (inspiration or expiration (forced/resting), no air flow, pneumothorax, not possible). What muscles, or none, are contracting? (mm Hg) What’s happening? (direction of air flow) and (forced/resting) Muscles P IP 757 P A 761 Resting expiration none P IP 790 P A 797 Forced expiration Internal intercostals & abdominals P IP 735 P A 742 Forced inspiration Diaphragm, external intercostals, scalenes, sternocleidomastoids P IP 760 P A 760 Pneumothorax, no air flow None, or it doesn’t matter P IP 754 P A 759 Resting inspiration Diaphragm & external intercostals P IP 761 P A 757 Not possible none 3. (10 points). An elephant decides to breathe through its trunk rather than its mouth. Its trunk has a radius that is 1/2 of that of its normal respiratory tract, but is 3 times longer, with a volume of 800ml. Its normal tidal volume is 4000ml, the dead space not counting the trunk is 1200ml, and breathes an average of 10 breaths per minute. In order to maintain the same alveolar P O 2 and P CO 2 : (Show the equations and calculations you use). a. What must be its new tidal volume assuming it doesn’t change the respiratory frequency? V A = (Vtid – Vdead) x frequency . Vdead is now 1200+800 ml = 2000 ml. So Vtid must increase by 800 ml in order to maintain the same alveolar ventilation , otherwise the alveolar P O 2 and P CO 2 will change.
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