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During inhalation – |
the diaphragm and rib muscles contract. |
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From which structures do oxygen molecules move from the lungs to the blood? |
Alveoli |
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Which statement is correct? |
In the blood, oxygen is bound to hemoglobin, a protein found in red blood cells. |
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After blood becomes oxygenated, |
it returns to the heart, and is then pumped to body cells. |
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Hemoglobin |
is a protein that can bind four molecules of oxygen. |
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Which of the following descriptions accurately describes Boyle’s law? |
The pressure of gas in your lungs is inversely proportional to the volume in your lungs. |
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Which muscles, when contracted, would increase the volume of air in the thoracic cavity? |
diaphragm and external intercostals |
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Which pressure is the result of the natural tendency of the lungs to decrease their size (because of elasticity) and the opposing tendency of the thoracic wall to pull outward and enlarge the lungs? |
intrapleural pressure |
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During an allergic reaction, which of the following would aid respiration? |
epinephrine |
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If the transpulmonary pressure equals zero, what will happen to the lung? |
lungs will collapse |
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Which form of CO2 transport accounts for the least amount of CO2 transported in blood? |
dissolved in plasma |
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If a red blood cell is 100% saturated, how many molecules of O2 are bound to it? |
1 billion molecules of O2 |
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From the oxygen-hemoglobin dissociation curve, hemoglobin is __________ when the partial pressure of oxygen is 40 mm Hg. Would this be in the lungs, inactive tissues, or active tissues? |
75% saturated; in the inactive tissues |
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Predict which way exercise would shift the oxygen-hemoglobin dissociation curve. Would this shift in the curve increase or decrease hemoglobin saturation? |
The curve would shift to the right thus decreasing the hemoglobin saturation |
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How is the majority of CO2 transported in blood? |
converted to and transported as bicarbonate ions |
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In the lungs, O2 loading facilitates CO2 unloading from hemoglobin. This is known as __________. |
the Haldane effect |
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What area in the brain sets the respiratory rhythm? |
ventral respiratory group (VRG) – Yes, the VRG is the rhythm-generating center in the medulla. |
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Inspiratory neurons send information to the diaphragm via what nerve? |
phrenic nerve – Yes, the phrenic nerve innervates the diaphragm. Stimulation causes the diaphragm to contract (increasing volume and decreasing pressure), thus causing inspiration. |
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What directly stimulates the central chemoreceptors, thus increasing respiration? |
H+ (hydrogen ions) – Yes, hydrogen ions (H+) stimulate the central chemoreceptors. CO2 is converted to H+ in the extracellular fluid of the brain. |
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As a result of hyperventilation, what will happen to the partial pressures of CO2 (pCO2) and pH? |
decreased pCO2 and increased pH – Yes, pCO2 would decrease and pH would increase. As CO2 is blown off, H+ would decrease, thus increasing pH. |
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Which receptors inhibit inspiration during hyperinflation of the lungs? |
pulmonary stretch receptors -Yes, inspiration stimulates the pulmonary stretch receptors (PSRs), which send input to the respiratory centers, inhibiting further inspiration. |
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What stimulates increased respiration at the beginning of exercise? |
sensory input from receptors in joints, neural input from the motor cortex, and other factors -Yes, at the beginning of exercise, blood gases have not changed; thus, other factors such as anticipation of exercise contribute to the increase in respiration. |
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A homeostatic control mechanism controls respiration. What acts as the effector(s) in this system? |
respiratory muscles – Yes, the respiratory muscles change the volume of the thoracic cavity (and thus the pressure), resulting in inspiration and expiration. |
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