When a person experiences impaired gas exchange, how does the body compensate to maintain homeostasis?
The body increases glucose absorption.
The body decreases the respiratory rate.
The body increases the blood pressure.
The body decreases alveoli surface area.
The Correct Answer is C
Choice A rationale
Increasing glucose absorption is a metabolic function primarily related to energy production and insulin regulation, not the immediate stabilization of gas exchange. While the body requires glucose for cellular respiration, the acute compensatory mechanisms for hypoxia or hypercapnia are focused on the cardiovascular and respiratory systems. Enhancing nutrient uptake does not address the physiological need for better oxygen delivery or carbon dioxide removal during a state of impaired gas exchange or respiratory distress.
Choice B rationale
Decreasing the respiratory rate would be maladaptive during impaired gas exchange. When the body senses low oxygen or high carbon dioxide levels, the brain's respiratory centers normally trigger tachypnea, or an increased rate, to enhance ventilation. Reducing the rate would lead to further CO2 retention and worsening hypoxia. Homeostasis requires the body to move more air across the alveolar-capillary membrane, so a decrease in breathing frequency would actually exacerbate the underlying gas exchange problem.
Choice C rationale
When gas exchange is impaired, the body experiences hypoxia, which triggers the sympathetic nervous system. This results in an increased heart rate and systemic vasoconstriction to boost cardiac output and blood pressure. By increasing blood pressure, the body attempts to maintain perfusion to vital organs and improve the transport of available oxygen to tissues. This cardiovascular compensation is a standard homeostatic response to ensure that limited oxygen supplies are distributed as efficiently as possible.
Choice D rationale
Decreasing the surface area of the alveoli would significantly worsen impaired gas exchange. Effective respiration relies on a large surface area for the diffusion of gases between the lungs and the blood. Pathological conditions like emphysema decrease this area, leading to chronic illness. To maintain homeostasis, the body requires maximum functional surface area. The body cannot voluntarily decrease this area as a compensatory mechanism; doing so would only further reduce the efficiency of oxygen uptake.
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Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Choice A rationale
A decrease in red blood cells, known as anemia, leads to symptoms such as fatigue, pallor, and shortness of breath. Red blood cells carry oxygen via hemoglobin to the tissues. While aplastic anemia involves a reduction in red blood cells, this specific deficiency does not cause petechiae. Petechiae are small, pinpoint purple or red spots on the skin caused by minor hemorrhaging from broken capillary vessels, which is related to clotting factors.
Choice B rationale
A decrease in leukocytes, or white blood cells, is known as leukopenia. This condition significantly increases the risk of infection and reduces the body's ability to mount an immune response. While leukopenia is a component of the pancytopenia seen in aplastic anemia, it does not manifest as petechiae. The normal white blood cell count ranges from 4,500 to 11,000 cells per microliter; levels below this indicate an increased susceptibility to pathogens.
Choice C rationale
Petechiae occur because of a decrease in platelets, a condition called thrombocytopenia. Platelets are essential for blood clotting and maintaining the integrity of the capillary walls. In aplastic anemia, the bone marrow fails to produce enough platelets. When the platelet count drops below the normal range of 150,000 to 450,000 per microliter, spontaneous bleeding into the skin occurs. This manifests as the small, red or purple spots known as petechiae.
Choice D rationale
Hemoglobin is the protein in red blood cells that binds to oxygen. A decrease in hemoglobin levels, which are normally 12 to 16 g/dL for women and 14 to 18 g/dL for men, results in tissue hypoxia. While low hemoglobin is a feature of aplastic anemia, its primary clinical manifestations are related to oxygenation rather than skin hemorrhages. Hemoglobin levels do not influence the primary hemostasis required to prevent the formation of petechiae.
Correct Answer is C
Explanation
Choice A rationale
High altitudes present a lower partial pressure of oxygen in the atmosphere, which directly leads to systemic hypoxemia. In patients with sickle cell anemia, deoxygenated hemoglobin S polymerizes into rigid, rod-like structures that distort the red blood cell into a sickle shape. This process occludes microvasculature, leading to tissue ischemia and infarction. Therefore, exercising at high altitudes is contraindicated as it significantly increases the risk of a vaso-occlusive sickling crisis.
Choice B rationale
Prescribed pain medications, such as opioids or non-steroidal anti-inflammatory drugs, are essential for managing the intense pain associated with an ongoing vaso-occlusive crisis. However, these medications do not address the underlying physiological triggers of sickling itself. While they provide symptomatic relief and improve the quality of life during an episode, they do not function as a primary preventative measure to stop the initial formation of sickled erythrocytes in the bloodstream.
Choice C rationale
Dehydration leads to increased blood viscosity and a higher concentration of hemoglobin S within the red blood cells. Reduced plasma volume slows down the transit time of erythrocytes through the narrow capillaries, providing more time for deoxygenation and subsequent polymerization of hemoglobin. Maintaining adequate hydration is a critical preventative strategy because it ensures optimal blood flow and dilutes the concentration of sickling-prone cells, thereby reducing the likelihood of vessel occlusion and crisis.
Choice D rationale
While a balanced diet is important for overall health, a specific high-protein or high-fat diet has no direct scientific link to the prevention of erythrocyte sickling. Sickle cell anemia is a genetic hemoglobinopathy, not a nutritional deficiency that responds to macronutrient manipulation. High-fat diets may actually increase cardiovascular risks or lead to gallbladder issues, which are already common complications in this population, but they do not stabilize the hemoglobin molecule or prevent crises.
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