Which of the following is FALSE concerning airway resistance (R)?

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: 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.

Correct Answer: C

Rationale: Ectoderm forms the epidermis (C), the skin's outer layer, via surface ectoderm differentiation into stratified squamous epithelium. Blood (A) originates from mesoderm, specifically hemangioblasts in the yolk sac and later bone marrow. The dermis (B), beneath the epidermis, is mesodermal, arising from fibroblasts and connective tissue. The spleen (D) is also mesodermal, from mesenchyme in the dorsal mesogastrium. C is correct epidermis' ectodermal lineage, forming skin and neural structures, distinguishes it from the mesodermal origins of the others.

Correct Answer: A

Rationale: Bowman's capsule, enclosing the glomerulus, is lined with simple squamous epithelium (A), thin for filtration of plasma into the nephron. Simple cuboidal (B) lines PCT, not capsule. Stratified squamous (C) is protective (e.g., skin), not filtration-suited. Transitional (D) stretches in the bladder, irrelevant here. A is correct simple squamous' flatness optimizes filtration, unlike the others' structures.