Given a PCO₂ = 600 mmHg and a HCO₃⁻ = 28 mEq/L there is a:

Correct Answer: C

Rationale: PCO₂ = 600 mmHg (extreme hypercapnia) with HCO₃⁻ = 28 mEq/L (near normal) indicates acute respiratory acidosis. Using Henderson-Hasselbalch (pH = 6.1 + log(HCO₃⁻ / (0.03 · PCO₂))), pH ≈ 6.1 + log(28 / 18) ≈ 6.3, severely acidic due to high PCO₂. Choice A (metabolic) requires low HCO₃⁻. Choice B needs higher HCO₃⁻ (e.g., 40). Choice D implies compensation (HCO₃⁻ rise, e.g., 40-50), not seen here. Choice E (alkalosis) contradicts PCO₂. Acute hypoventilation (e.g., obstruction) causes this uncompensated state, making C accurate.

Correct Answer: B

Rationale: the lung converts angiotensin I to II (AII) via ACE but doesn't metabolize AII degradation occurs elsewhere (e.g., liver). Choice A is true (ACE activity). Choice C is correct (bradykinin inactivation). Choice D is accurate (serotonin uptake). Choice E (arachidonic acid) occurs via cyclooxygenase. The lung's ACE role is synthetic, not catabolic for AII, making B the exception.

Correct Answer: D

Rationale: total lung capacity (TLC) = vital capacity (VC) + residual volume (RV), e.g., 4.8 + 1.2 = 6 L in men. Choice A (VC + TV) overcounts inspiratory volume. Choice B (VC + FRC) double-counts RV and ERV. Choice C (TV + RV) is too small (≈1.7 L). TLC encompasses all lung volume (RV + ERV + TV + IRV), and VC (ERV + TV + IRV) plus RV completes it. E aligns with standard lung volume definitions.

Correct Answer: A

Rationale: decreased phosphate lowers 2,3-DPG, shifting the O₂ dissociation curve left (higher Hb-O₂ affinity, P₅₀ down). Choice B (altitude) increases 2,3-DPG, shifting right. Choice C (cortisol) may indirectly raise 2,3-DPG via metabolism, shifting right. Choice D (decreased pH) shifts right (Bohr effect, H⁺ reduces affinity). Choice E (aldosterone) has minimal direct effect but isn't listed. Phosphate depletion (e.g., starvation) reduces 2,3-DPG, countering right-shift factors like CO₂, temperature, or hypoxia, making A the exception in this context.

Correct Answer: A

Rationale: A pandemic describes the most severe spread of influenza, characterized by a new virus subtype spreading globally across multiple continents, affecting large populations with significant morbidity and mortality. This differs from an epidemic, which is a regional or community-wide outbreak, less severe in scope. An outbreak is even smaller, often localized, while antigenic refers to the virus's properties, not its spread. Historically, influenza pandemics like 1918 and 2009 demonstrated widespread devastation due to lack of immunity and rapid transmission. Understanding these terms is vital for public health responses pandemics require global coordination, unlike smaller-scale events. The nurse educating about influenza spread would emphasize ‘pandemic' as the term for the most severe scenario, reflecting its impact on healthcare systems and populations, necessitating urgent vaccination and containment strategies.