Regarding the Oâ‚‚ dissociation curve:

Correct Answer: B

Rationale: 2,3-DPG levels rise at altitude (hypoxia response), shifting the curve right. Choice A is true; PCO₂ shifts it right (Bohr effect). Choice C is false; deoxy-Hb is tense (T state), not relaxed (R state). Choice D is wrong; CO's affinity is ≈240x, shifting left by reducing available Hb, not curve shape. Altitude adaptation increases 2,3-DPG, aiding O₂ unloading (P₅₀ up), making B the accurate chronic response.

Correct Answer: C

Rationale: lower regions (base) ventilate better than upper (apex) due to gravity and compliance gradients. Choice A is true (TV ≈ 500 mL). Choice B is correct (dead space ≈ 150-160 mL). Choice D is accurate (Bohr's method). Choice E (none) is false. Base ventilation exceeds apex (e.g., 4:1 ratio upright), reflecting diaphragm motion and pleural pressure, making C the error.

Correct Answer: D

Rationale: increased carboxyhemoglobin (COHb) shifts the curve left, not right, by enhancing Hb-O₂ affinity (CO binds 240x stronger). Choice A (temperature), B (PCO₂), and C (H⁺) shift it right via the Bohr effect, aiding O₂ unloading (P₅₀ up, e.g., 26 to 30 mmHg). Choice D (DPG) also shifts right. COHb reduces available Hb, left-shifting the curve for remaining O₂, impairing tissue delivery (e.g., in poisoning), opposite to exercise adaptations. E's distinct effect makes it the exception.

Correct Answer: C

Rationale: arterial blood carries only ≈5-7% of CO₂ in dissolved form (≈0.3 mL/100 mL at PaCO₂ 40 mmHg), not 20% total CO₂ is ≈48-50 mL/100 mL, mostly as HCO₃⁻ (70-80%) and carbamino compounds (10-20%). Choice A is true; O₂ solubility (0.003 mL/mmHg/100 mL) is ≈20x less than CO₂ (0.06). ' deoxygenation enhances CO₂ binding (Haldane effect) via deoxy-Hb's higher affinity. Choice D is plausible; venous hematocrit may rise slightly due to plasma shifts, though minimal in normals. Dissolved CO₂ contributes a small fraction, and C's overestimate contradicts standard physiology (e.g., 20% would imply 10 mL/100 mL, far exceeding solubility), making it the false statement.

Correct Answer: B

Rationale: Shallow respirations in an older client with flu suggest difficulty oxygenating effectively, often due to mucus buildup or fatigue. Elevating the head of the bed helps by using gravity to open the airways, reducing pressure on the diaphragm and improving lung expansion, which is especially beneficial for older adults with weakened respiratory muscles. A humidifier adds moisture to the air, loosening mucus and easing breathing, which is critical when flu causes thick secretions. Antipyretics reduce fever but don't directly address shallow breathing, though fever management supports overall comfort. Analgesics might relieve pain but not respiratory effort. A face mask could worsen breathing by restricting airflow unless oxygen is medically indicated. The nurse's advice focuses on non-invasive, practical measures to enhance airflow and comfort, tailored to the client's age and flu-related respiratory challenges, ensuring better oxygenation and reduced strain.