Which of the following will the have the highest percentage of CO2?

Correct Answer: B

Rationale: CO2 percentage correlates with PCO2, highest where metabolic CO2 accumulates. Pulmonary arteries carry deoxygenated blood from the right heart to lungs, with PCO2 ~45-46 mmHg venous blood richest in CO2 from tissues, topping the list. Alveolar air equilibrates with arterial blood at ~40 mmHg during gas exchange. Pulmonary veins, post-exchange, carry oxygenated blood with PCO2 ~40 mmHg, arterial levels. Interstitial fluid's PCO2 (~45 mmHg or less) mirrors venous blood or local metabolism but isn't a standard respiratory metric. Systemic arteries (not listed) are also ~40 mmHg. Pulmonary arteries, transporting CO2-rich blood for exhalation, have the highest PCO2, reflecting their pre-exchange role, distinguishing them from oxygenated or equilibrating sites in the respiratory cycle.

Correct Answer: A

Rationale: Airway resistance (R ∝ 1/r^4) peaks in large airways (trachea, bronchi), where turbulent flow dominates (~80% of R), despite smaller radii in later generations (bronchioles). Their vast number increases cross-sectional area (~300 cm² vs. 3-4 cm²), reducing total R distally false. Normally, R is highest in large airways true. Increased R (e.g., asthma) lowers FEV1/FVC (<70%) true. Loss of elasticity (emphysema) and bronchoconstriction (asthma) raise R true. The false claim of increasing R in later generations misreads branching dynamics resistance drops as area rises, making large airways the primary site, aligning with airflow physiology.

Correct Answer: A

Rationale: The troposphere, extending ~0-12 km above Earth's surface, contains ~80% of atmospheric mass and nearly all weather phenomena clouds, rain, storms driven by solar heating, convection, and water vapor. The stratosphere (~12-50 km) holds the ozone layer, stable and dry, with minimal weather. The mesosphere (~50-85 km) is cold, with rare noctilucent clouds, not typical weather. The thermosphere (~85-600 km) is thin, hot from solar radiation, and weatherless. The troposphere's density and dynamics (e.g., Hadley cells) foster weather, per meteorological data (e.g., AMS), making it the key layer, distinct from higher, less active regions.

Correct Answer: C

Rationale: The lateral nasal wall's blood supply (A) includes the sphenopalatine (external carotid) and anterior ethmoidal (internal carotid) arteries, making A true. Innervation (B) via ophthalmic (V1) and maxillary (V2) branches of the trigeminal nerve is correct. Lymphatic drainage (D) to submandibular and retropharyngeal nodes aligns with nasal anatomy. However, venous drainage (C) primarily goes to the facial vein and pterygoid plexus, not mainly to the cavernous sinus via a large emissary vein that's more relevant to the dangerous triangle of the face or specific infections. Small connections exist via ethmoidal veins, but C overstates this route, making it the least accurate.

Correct Answer: C

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.