Which statement about diffusion of gas across the alveolar capillary membrane is true?
Diffusion of gas does not depend on the partial pressure gradient
Gas diffuses from high partial pressure to low partial pressure
Gas diffuses from low partial pressure to high partial pressure
Equilibrium can be reached without partial pressure gradient
The Correct Answer is B
A. Diffusion of gas does not depend on the partial pressure gradient: Incorrect -gas diffusion across membranes depends on partial pressure gradients (and membrane properties).
B. Gas diffuses from high partial pressure to low partial pressure: Correct -diffusion follows the partial pressure gradient (for example O₂ moves from alveoli where PO₂ is higher into blood where PO₂ is lower).
C. Gas diffuses from low partial pressure to high partial pressure: Incorrect -that direction would require active transport; gases passively diffuse down their gradients.
D. Equilibrium can be reached without partial pressure gradient: Incorrect -equilibrium is reached when partial pressures equalize; without a gradient diffusion won’t proceed.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
A. Glomerulus:The glomerulus is the filtration site; ADH/aldosterone act downstream on tubular epithelial cells, not on glomerular filtration directly.
B. Loop of Henle: The loop establishes the medullary gradient; ADH/aldosterone have limited direct action here (ADH affects water permeability mainly in collecting ducts; aldosterone acts mainly on DCT/collecting duct).
C. Vasa recta:Vasa recta are blood vessels that help preserve the medullary gradient (countercurrent exchange) but are not the primary hormone-target epithelial segments for ADH/aldosterone.
D. DCT and collecting duct:Aldosterone acts on the distal convoluted tubule and cortical collecting duct to increase Na⁺ reabsorption (and K⁺ secretion); ADH acts on the late DCT and collecting duct to increase water reabsorption by inserting aquaporins -together they adjust water and sodium retention.
Correct Answer is A
Explanation
A. Nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, alveoli: This correctly lists the anatomical pathway air follows from entry to the gas-exchange sites.
B. Nasal cavity, pharynx, trachea, larynx, bronchi, bronchioles, alveoli: This places the trachea before the larynx (incorrect order); the larynx is between the pharynx and trachea.
C. Nasal cavity, pharynx, larynx, trachea, bronchioles, bronchi, alveoli: This incorrectly reverses bronchioles and bronchi -bronchi branch into bronchioles, not the other way around.
D. Nasal cavity, larynx, pharynx, trachea, bronchi, bronchioles, alveoli: This places the larynx before the pharynx (incorrect); air passes through the pharynx first then the larynx.
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