A&P Lab 10
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Effect of inspiration on thoracic volume
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Increase
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Effect of increased thoracic volume on lung volume
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Increase
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Effect of expansion of the lungs on alveolar volume
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Increase
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Effect on intra-alveolar pressure if alveolar volume increases
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Decrease
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Effect on air movement into the alveoli if intra-alveolar pressure decreases below atmospheric pressure
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Increase
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Effect on the ease of lung expansion when compliance decreases
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Decrease
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Effect on compliance when the collapsing force of the lungs increases, as in respiratory distress syndrome
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Decrease
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Effect of emphysema on compliance
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Decrease
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Effect on diffusion rate of a gas if the partial pressure gradient is increased
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Increase
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Effect on diffusion rate of a gas if the thickness of the membrane is increased
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Decrease
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Effect on diffusion rate of a gas if the surface area of the membrane is increased
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Increase
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Effect on the amount of oxygen bound to hemoglobin when pH decreases
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Decrease
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Effect on the amount of oxygen bound to hemoglobin when the partial pressure of carbon dioxide decreases
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Increase
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Effect on the amount of oxygen bound to hemoglobin when temperature increases
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Decrease
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Effect of increased blood carbon dioxide on breathing rate and depth
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Increase
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Effect of decreased blood pH on breathing rate and depth
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Increase
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Effect of greatly decreased blood oxygen level on breathing rate and depth
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Increase
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Effect of action potentials that come through collateral fibers from motor pathways on breathing rate during exercise
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Increase
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Effect of stimulation of proprioceptors on respiratory rate during exercise
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Increase
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Effect of stimulation of touch, thermal, and pain receptors in the skin on respiratory rate
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Increase
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During breath-holding, what happens to the blood levels of CO2? ___ What happens to blood pH? ___ Why is the subject's response (examine change in minute ventilation) to these changes beneficial?
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1- Increase 2- Decrease 3- The increase in minute ventilation increases the quantity of CO2 given off, raising pH back to "normal."
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During hyperventilation, what happens to the blood levels of CO2? ___ What happens to blood pH? ___ Why is the subject's response to these changes beneficial?
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1- Decrease 2- Increase 3- The decrease in minute ventilation conserves CO2, lowering pH back to "normal."
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During rebreathing air, what happens to the blood levels of CO2? ___ What happens to blood pH? ___ Why is the subject's response to these changes beneficial?
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1- Increase 2- Decrease 3- The increase in minute ventilation increases the quantity of CO2 given off, raising pH back to "normal.
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How did increasing the dead space affect respiratory rate and tidal volume? Explain the reason for these differences.
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Respiratory rate decreases and tidal volume increases. Increasing the dead space means more volume of each breath does not participate in gas exchange; therefore, larger breaths are necessary just to move more air that does not participate in gas exchange.
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Which changed more when the dead space was increased, minute ventilation or alveolar ventilation rate? Explain.
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Minute ventilation. Alveolar ventilation rate represents the volume of air participating in gas exchange, and increasing the dead space does not affect this volume. In fact, the dead space is subtracted out before this calculation is made.
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What is the stimulus responsible for initiating these changes in breathing rate and depth, and what area of the brain is responsible for processing this information?
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With increasing dead space, an individual will rebreathe his own air if he or she does not take larger breaths. The CO2 will stimulate the respiratory center in the medulla oblongata, increasing the depth of respiration.
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How do the concepts examined in this exercise apply to construction of a snorkel for breathing under water?
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The air trapped in a snorkel is physiological dead space. It is theoretically possible to construct a snorkel that would contain as much (or more) dead space as a person's vital capacity. In that case, the individual would never exchange fresh air with the atmosphere and would suffocate.
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The air we breathe is approximately 78% nitrogen and 21% oxygen. The remaining 1% is a mixture of other gases, including 0.04% carbon dioxide. Here in Kearney, Nebraska (elevation approximately 2500 feet), the atmospheric pressure is approximately 680 mm Hg. What are the partial pressures of nitrogen, oxygen, and carbon dioxide at sea level (atmospheric pressure 760 mm Hg) and here in Kearney?
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Sea Level Kearney, NE pN2 593 mm Hg 530 mm Hg pO2 160 mm Hg 143 mm Hg pCO2 0.30 mm Hg 0.27 mm Hg
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What effect will these differences in partial pressure (compare sea level to Kearney) have on the movement of respiratory gases between the alveoli and capillaries? That is, will O2 move into the bloodstream easier in Kearney compared to sea level? Why or why not? What about CO2? (Remember, CO2 moves in the opposite direction!)
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The gradient for O2 in Kearney is less compared to sea level, so O2 will move in slower. The gradient for CO2 in Kearney is larger, however, so CO2 will move out more quickly.
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In certain respiratory disorders, such as pulmonary fibrosis, the elastic recoil of the lungs is reduced. Which respiratory air volumes will be most affected by this condition, and why?
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The decrease in compliance will affect the timed expirations the most (FEV1, FEV3, %FEVT1, %FEVT3). The individual will be able to exhale the same quantity as an individual without these kinds of conditions, but he or she will not be able to exhale quickly or forcefully.
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A patient has severe emphysema that has extensively damaged the alveoli and reduced the surface area of the respiratory membrane. Although the patient is receiving oxygen therapy, he still has a tremendous urge to take a breath (because he does not feel as if he is getting enough air). Why does this occur?
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The reduced surface area affects the diffusion of both O2 and CO2. Hence, CO2 is retained, stimulating the respiratory center.
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Patients with diabetes mellitus may occasionally take too little insulin. This can result in rapid metabolism of lipids and the accumulation of acidic by-products of lipid metabolism in the circulatory system (a condition called metabolic acidosis). What effect would this have on respiration, and why is the change beneficial?
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The decrease in pH would stimulate the respiratory center to increase minute ventilation, increasing the amount of CO2 expelled.
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A hysterical individual is hyperventilating. You know that breathing into a paper bag is recommended for hyperventilation, so you have the individual breathe into a paper bag. Soon the individual calms down and his breathing becomes normal. When he was breathing into the paper bag, however, carbon dioxide was trapped, and, as a result, his blood carbon dioxide levels increased. When blood carbon dioxide levels increase, the "urge" to breathe is also increased. Therefore, breathing into a paper bag should make the individual hyperventilate more. Why is breathing into a paper bag recommended for hyperventilation?
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Since the individual has been hyperventilating, he has driven off CO2. Rebreathing air from a paper bag will simply return CO2 levels to "normal."
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__/===----___ Propose an explanation that would account for the increased pH immediately following the start of the race, and the decreased pH at the end of the race.
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Initially feedback from proprioceptors in muscles and joints stimulates the respiratory center and the runner hyperventilates, driving off CO2 and raising pH. Later in the race lactic acid begins to accumulate, lowering pH.
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If a person has stopped breathing and requires pulmonary resuscitation, would it be better (at least in theory) to administer 100% oxygen or a mixture of 99% oxygen and 1% carbon dioxide? Why?
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The primary stimulus for breathing is elevated levels of CO2. Including some CO2 in the mixture will stimulate the individual's respiratory center without compromising O2 delivery.
