ATI LPN
NCLEX PN Questions Respiratory System Questions
Question 1 of 5
Which layer of the heart wall consists of mesothelium and connective tissue?
Correct Answer: A
Rationale: The epicardium, the heart wall's outer layer (visceral pericardium), comprises mesothelium (a simple squamous epithelium) and underlying connective tissue, providing a smooth, protective surface with coronary vessels. The myocardium is cardiac muscle, driving contraction, not mesothelium-based. The endocardium, the inner lining, is endothelium and connective tissue but distinct from the outer epicardium. The fibrous pericardium is dense connective tissue, lacking mesothelium. The epicardium's structure reduces friction with the pericardial sac and supports vascular supply, a key layer in heart anatomy, critical in conditions like epicarditis affecting this surface.
Question 2 of 5
Which structure in the heart initiates action potentials that stimulate contraction of the heart at constant rate of about 100 beats per minute?
Correct Answer: D
Rationale: The sinoatrial (SA) node initiates action potentials, pacing the heart at ~100 beats per minute intrinsically, though nerves adjust this to ~70 bpm normally. Located in the right atrium, it's the natural pacemaker, firing spontaneously via pacemaker cells' ion shifts. Cardiac accelerator nerves (sympathetic) speed it up, not initiate. The AV node delays signals, not starts them (~40-60 bpm if SA fails). The cardiovascular center in the medulla modulates rate, not generates. The SA node's primacy ensures rhythm, key in physiology and arrhythmias like sinus tachycardia where its rate shifts.
Question 3 of 5
Heart murmurs are often heard in individuals with abnormalities in the _____ of the heart.
Correct Answer: A
Rationale: Heart murmurs stem from valve abnormalities stenosis (narrowing) or regurgitation (leakage) disrupting smooth blood flow, causing turbulence audible as whooshes. Myocardium issues (e.g., infarction) affect contraction, not murmurs directly. SA/AV node problems alter rhythm, not flow sounds. Valves (tricuspid, mitral, pulmonary, aortic) regulate direction; defects like mitral prolapse create murmurs, key in diagnosis via auscultation, distinguishing benign from pathological flow disruptions.
Question 4 of 5
The chamber of the heart that normally has the thickest wall is the:
Correct Answer: D
Rationale: The left ventricle has the thickest wall (~1-1.5 cm), its myocardium pumping against systemic pressure (~120 mmHg), far exceeding right ventricle (~0.3-0.5 cm, ~25 mmHg pulmonary) or atria (~0.1-0.2 cm). This thickness meets workload, key in hypertrophy or failure, a fundamental adaptation in cardiac anatomy and function.
Question 5 of 5
The organ of the respiratory system that traps bacteria with a ring of tonsils is the:
Correct Answer: B
Rationale: The pharynx (B) traps bacteria with tonsils (e.g., palatine, adenoids), per the key lymphoid tissue filters pathogens (e.g., 10ⶠbacteria/day). The nose (A) uses mucus/hairs, not tonsils. The larynx (C) and trachea (D) lack tonsils mucus alone clears debris. Pharyngeal tonsils (Waldeyer's ring) produce lymphocytes, per immunology, guarding against inhaled/oral microbes unlike A's physical trap, C's vocal role, or D's conduit function, B's immune barrier is distinct.