ATI LPN
NCLEX PN Questions Respiratory System Questions
Question 1 of 5
Which of the following organs functions as an air conditioner?
Correct Answer: C
Rationale: Nasal chambers act as an air conditioner, warming, humidifying, and filtering air before it reaches the lungs. Their mucous membranes and turbinates increase surface area, trapping dust and moistening dry air via blood vessel heat, optimizing it for alveolar exchange. The larynx directs air and protects the airway, not conditioning it. The pharynx conducts air but lacks significant conditioning features. 'All' is incorrect nasal chambers alone perform this role. This preconditioning prevents lung irritation, a primary respiratory defense, key in understanding upper airway function and conditions like rhinitis affecting air quality.
Question 2 of 5
What of the following chambers of the heart contain deoxygenated blood?
Correct Answer: C
Rationale: The right atrium and right ventricle contain deoxygenated blood, received from systemic veins (vena cavae) into the atrium, then pumped via the ventricle to the lungs for oxygenation. The left atrium and ventricle hold oxygenated blood from pulmonary veins, destined for the body. 'Left atrium only' or 'right ventricle only' ignores paired chamber roles. This right-side deoxygenation reflects the heart's dual circulation systemic and pulmonary a fundamental division ensuring oxygen delivery, critical in understanding cardiac flow and congenital defects mixing these streams.
Question 3 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 4 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 5 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.