What causes air to move into the lungs during inspiration?
Muscle contraction of upper airways
Partial pressure gradients for oxygen and carbon dioxide
Pressure gradient between atmosphere and alveoli
Concentration gradients for oxygen and carbon dioxide
The Correct Answer is C
A. Muscle contraction of upper airways: Upper airway muscle movement does not create the main pressure change driving inspiration
B. Partial pressure gradients for oxygen and carbon dioxide: Partial pressure gradients drive gas diffusion across membranes, not bulk airflow into lungs
C. Pressure gradient between atmosphere and alveoli: Contraction of the diaphragm/intercostals lowers intrapulmonary pressure relative to atmospheric pressure, causing air to flow in
D. Concentration gradients for oxygen and carbon dioxide: Concentration gradients drive diffusion at the alveolar–capillary level, not the gross movement of air into the lungs
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
A. Inflammation: inflammation causes vasodilation and increased capillary permeability so immune cells and plasma components reach the injured/infected tissue.
B. Activation of NK cells: NK cell activation is an innate cytotoxic response against infected or malignant cells but does not itself describe the vascular changes listed.
C. Complement activation: complement promotes opsonization, chemotaxis, and membrane attack, but the described vasodilation/permeability hallmark is inflammation.
D. Activation of mononuclear phagocytic system: activation of macrophages/monocytes contributes to defense and cleanup, but the vascular response described is specifically the inflammatory process.
Correct Answer is B
Explanation
A. Pepsinogen: pepsinogen is secreted by chief cells, not parietal cells.
B. Hydrochloric acid: parietal cells secrete HCl, which acidifies the stomach and helps activate pepsinogen.
C. Mucus: mucus is secreted by mucous (surface) cells to protect the gastric epithelium, not by parietal cells.
D. Pepsin: pepsin is the active protease formed from pepsinogen by HCl; parietal cells secrete HCl, not active pepsin.
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