Which of the following functions by filtering and keeping the mucus and dirt away from our lungs?

Correct Answer: A

Rationale: Cilia, hair-like structures on respiratory epithelial cells, filter mucus and dirt from the lungs via the mucociliary escalator. They beat rhythmically to sweep trapped particles upward to the pharynx for swallowing or expulsion, protecting deeper airways. Bronchioles, small air passages, lack cilia's filtering role they conduct air. 'Hairs in the lungs' misrepresents nasal hairs, which filter larger particles upstream, not in the lungs. 'All' is inaccurate cilia alone perform this task in the lower tract. This mechanism is crucial for lung defense, impaired in conditions like cystic fibrosis, highlighting cilia's role in respiratory health.

Correct Answer: A

Rationale: Pectinate muscles, muscular ridges on the right atrium's anterior wall and auricles, enhance atrial contraction and surface area, aiding blood flow to the ventricle. Trabeculae carneae are ventricular ridges, not atrial. Coronary sulci are external grooves, not muscles. Papillary muscles anchor valves in ventricles, not atria. Named for their comb-like appearance, pectinate muscles distinguish the right atrium from the smoother left, a structural feature boosting atrial efficiency, key in understanding chamber-specific anatomy and atrial function in the cardiac cycle.

Correct Answer: C

Rationale: Cardiac muscle has the most mitochondria per cell, reflecting its relentless energy demand beating nonstop, it relies on aerobic metabolism, rich in mitochondria for ATP production from oxygen and nutrients. Smooth muscle, in vessels or gut, has fewer, suited to slower, sustained action. Skeletal muscle varies more in endurance fibers, less in sprinters but averages below cardiac. 'Same number' ignores specialization. Cardiac cells' mitochondrial density (up to 35% of volume) supports constant work, a hallmark of its design, key in heart failure where energy deficits impair function.

Correct Answer: C

Rationale: The medulla oblongata houses the cardiovascular center, regulating heart rate via autonomic outputs parasympathetic (vagus) slows it, sympathetic accelerates it, responding to baroreceptors and chemoreceptors. The midbrain handles reflexes, not rate. The cerebrum governs higher functions, not direct control. The cerebellum coordinates movement, not heart. The medulla's integration of blood pressure and CO2 data ensures homeostasis, a vital autonomic hub, critical in conditions like brain stem injury where rate control fails, affecting survival.

Correct Answer: D

Rationale: Cardiomyoplasty uses the latissimus dorsi muscle, wrapped around a failing heart and paced electrically, to aid pumping an older technique for severe heart failure. Myocardial infarction is heart attack damage, not a procedure. Tetralogy of Fallot is a congenital defect. Cardiomyopathy is disease, not repair. This muscle wrap boosts contractility, key in end-stage failure management, though less common now with ventricular assist devices, a historical cardiac support method.