What is the most common cause of hypoxemia?
Ventilation-perfusion mismatch
Hyperventilation with hypocapnia
Reduced diffusion distance
Shunting
The Correct Answer is A
Choice A reason: Ventilation-perfusion (V/Q) mismatch, where lung regions receive inadequate ventilation or perfusion, is the most common cause of hypoxemia. Conditions like pneumonia or pulmonary embolism disrupt this balance, reducing oxygen exchange, making this the primary cause in clinical settings.
Choice B reason: Hyperventilation with hypocapnia lowers carbon dioxide but does not typically cause hypoxemia, as oxygen levels are usually maintained or increased. It affects acid-base balance more than oxygenation, making this an incorrect primary cause of low oxygen levels.
Choice C reason: Reduced diffusion distance is not a cause but a facilitator of gas exchange. Impaired diffusion (e.g., pulmonary edema) can contribute to hypoxemia, but V/Q mismatch is more prevalent across conditions, making this less common as a primary cause.
Choice D reason: Shunting, where blood bypasses ventilated alveoli, causes hypoxemia but is less common than V/Q mismatch. It occurs in specific conditions like congenital heart defects or ARDS, but V/Q mismatch predominates in most respiratory disorders, making this incorrect.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Choice A reason: Nasal mucosa is a portal of entry for cold viruses, not the primary source of spread. Sneezing propels virus-laden droplets, infecting others, making it the greatest spread mechanism, so this is incorrect for the source.
Choice B reason: Conjunctival surfaces can be an entry point but are not the main source of spread. Sneezing disperses viruses widely through respiratory droplets, driving transmission, so this is incorrect for the greatest source.
Choice C reason: Sneezing is the greatest source of cold virus spread, as it releases aerosolized droplets containing viruses, infecting others via inhalation or surface contact. This is the primary transmission mode, making it the correct choice.
Choice D reason: Fingers spread viruses via fomites, but sneezing generates more widespread droplet transmission. Hand contact is secondary to respiratory spread, so this is incorrect for the greatest source of cold virus spread.
Correct Answer is C
Explanation
Choice A reason: Release of inflammatory mediators drives inflammation, not angiogenesis. Pathological angiogenesis is excessive or abnormal vessel growth, often in diseases like cancer, so this is incorrect for the term.
Choice B reason: New vessel formation in response to injury is physiological angiogenesis, not pathological. Pathological angiogenesis involves abnormal, excessive growth, so this is incorrect for the described process.
Choice C reason: Pathological angiogenesis is excessive or abnormal blood vessel growth, seen in conditions like tumors or retinopathy. This matches the definition, making it the correct choice for the term.
Choice D reason: Inhibition of vessel formation is anti-angiogenic, not pathological angiogenesis. Excessive vessel growth defines the pathological state, so this is incorrect for the term.
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