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Hemoglobin has a greater affinity for oxygen in the lungs than it does in respiring tissue.

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The central pattern generator is the rhythm generator that sets the background rhythm for ventilation. However, the respiratory system must be able to respond to changes that require either increases or decreases in ventilation. Describe the receptors that are involved in modulating ventilation and how they function.

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There are a number of receptors involved...

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In the lung, the uptake of oxygen is in part determined by the ventilation- perfusion ratio, which varies throughout the lung. Describe how ventilation- perfusion is regulated within the lung itself. How would ventilation- perfusion ratio be affected by hyperventilation?

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The ratio of ventilation to perfusion is...

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The solubility of oxygen in solution is relatively low, necessitating the presence of hemoglobin to carry oxygen to active tissues. Hemoglobin exhibits several unique characteristics that make it well suited for the transport of oxygen. Describe the structure of hemoglobin and the mechanisms that can alter the affinity of hemoglobin for oxygen.

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Hemoglobin is composed of four subunits,...

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Which statement best describes the cause of decompression sickness?


A) Carbon dioxide bubbles come out of solution too quickly and burst blood vessels, especially in the brain.
B) Oxygen molecules are so tightly compressed due to pressure exerted by the water column that they cannot deliver oxygen to the tissues.
C) The oxygen molecule expands upon ascent and bursts, therefore causing a lack of oxygen to the tissues.
D) Carbon dioxide is driven into the cardiovascular system and causes acidosis.
E) Nitrogen gas bubbles form in the blood, joints, and nervous system as pressure decreases from too fast an ascent.

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Which of the following statements is FALSE regarding a leftward shift in the hemoglobin- oxygen dissociation curve?


A) It can be caused by an increase in blood pH.
B) Oxygen loading onto the hemoglobin is increased.
C) It can be caused by an increase in PCO2.
D) Affinity for oxygen is increased.
E) Hemoglobin is more saturated at a given PO2.

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Pulmonary edema describes a condition where the uptake of oxygen and unloading of carbon dioxide is reduced as a consequence of a(n)


A) thickening of the diffusion barrier by fluid accumulation in the pulmonary blood.
B) increase in the partial pressure of oxygen in the blood.
C) thickening of the diffusion barrier by fluid accumulation in the alveoli.
D) decrease in the partial pressure of oxygen in the alveolus.
E) decrease in the partial pressure of carbon dioxide in the alveolus.

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The Haldane effect describes the increase in the affinity of hemoglobin for CO2 in the presence of a lowered


A) concentration of bicarbonate (HCO3- ) .
B) PO2.
C) temperature.
D) PCO2.
E) pH.

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In the discussion of respiration, hydrogen ions were shown to be important in many aspects of ventilation. Thus, the respiratory system plays an important role in the regulation of acid- base balance. Describe the role of the respiratory system in the maintenance of acid- base balance.

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Typically, blood pH is somewhere around ...

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The majority of oxygen present within the blood is


A) bound to plasma proteins.
B) in the plasma as HCO3- .
C) dissolved within the plasma.
D) bound to hemoglobin in red blood cells.
E) bound to hemoglobin within the plasma.

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Breathing involves the interaction between a number of the control centers of ventilation. Describe the model that has been developed to describe the process of quiet breathing, including how volume of the lung is altered by this process.

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The model for quiet breathing involves t...

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Movement of oxygen and carbon dioxide between alveoli and blood occurs by what process?


A) facilitated diffusion
B) simple diffusion
C) osmosis
D) primary active transport
E) secondary active transport

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Respiratory acidosis will result from a(n)


A) decrease in blood CO2 concentration.
B) increase in blood CO2 concentration.
C) increase in carbon monoxide.
D) increase in blood bicarbonate.
E) decrease in blood bicarbonate.

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A majority of the control of ventilation resides within the central nervous system. Identify the regions of the brain that are important in the regulation of ventilation and how each of them functions in the control of ventilation.

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there is a...

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Which of the following causes a decrease in the PO2 of air as it enters the conducting zone of the lungs?


A) the increasing PCO2
B) decreasing alveolar PO2
C) warming of the air
D) the consumption of oxygen
E) humidifying the air

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During active breathing, bursts of action potentials are observed to occur


A) simultaneously in the inspiratory and expiratory motor neurons.
B) synchronously in the inspiratory and expiratory motor neurons.
C) asynchronously in the inspiratory and expiratory motor neurons.
D) exclusively in the inspiratory motor neurons.
E) exclusively in the expiratory motor neurons.

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Within an erythrocyte, the conversion of CO2 to bicarbonate is prevented from reaching equilibrium by the


A) presence of oxygen.
B) temperature of the body.
C) absence of a nucleus.
D) presence of hydrogen ions.
E) efflux of bicarbonate from the erythrocyte via the chloride shift.

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What is the partial pressure of oxygen in a gas mixture that is 40% oxygen, 40% argon, and 20% helium, when the total pressure of the gas is 1000 mm Hg?


A) 400 mm Hg
B) 600 mm Hg
C) 200 mm Hg
D) 100 mm Hg
E) 333 mm Hg

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The presence of bicarbonate ions in the blood has an important direct effect, aside from the transport of CO2, that involves


A) altering the activity of several receptors.
B) stimulating the proliferation of alveolar epithelial cells.
C) altering the activity of carbonic anhydrase.
D) maintaining acid- base balance.
E) altering the affinity of hemoglobin for oxygen.

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What is the partial pressure of oxygen in air at sea level?


A) 160 mm Hg
B) 400 mm Hg
C) 60 mm Hg
D) 600 mm Hg
E) 210 mm Hg

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