ATI LPN
Introduction of Respiratory System NCLEX Questions PN Questions
Question 1 of 5
Which of the following statements is true about involuntary breathing?
Correct Answer: D
Rationale: Involuntary breathing is regulated by neurons in the medulla and pons, brain stem regions that set the respiratory rhythm. The medulla's dorsal respiratory group initiates inspiration, while the pons fine-tunes it, responding to CO2 levels via chemoreceptors, ensuring automatic breathing without conscious effort. Bronchioles adjust airflow but don't control rhythm. Pulmonary arterioles regulate blood flow, not breathing. The alveolar-capillary network facilitates gas exchange, not its initiation. This neural control, via the phrenic nerve to the diaphragm, underscores breathing's autonomic nature, vital for survival, distinguishing it from voluntary overrides like holding breath, a key concept in respiratory neuroscience.
Question 2 of 5
Which of the following is used to reduce friction between the layers of membranes surrounding the heart?
Correct Answer: D
Rationale: Pericardial fluid, a serous secretion between the pericardium's parietal and visceral (epicardium) layers, reduces friction as the heart beats, ensuring smooth motion within the sac. Synovial fluid lubricates joints, not the heart. The endocardium lines heart chambers, not reducing external friction. Pleural fluid lubricates lung pleura, not the pericardium. This fluid's role about 15-50 mL prevents adhesion during cardiac cycles, a vital mechanism for uninterrupted pumping, central to cardiac physiology and relevant in pericardial effusion where excess fluid disrupts function.
Question 3 of 5
Which valve below prevents blood from flowing back into the right ventricle?
Correct Answer: C
Rationale: The pulmonary semilunar valve prevents blood from flowing back into the right ventricle, closing after systole as pulmonary artery pressure exceeds ventricular pressure, ensuring one-way flow to the lungs. The tricuspid valve stops backflow into the right atrium, not ventricle. The bicuspid (mitral) serves the left side. The aortic semilunar valve guards the left ventricle. This valve's role in pulmonary circulation is crucial, maintaining forward flow, key in right heart dynamics and conditions like pulmonary regurgitation affecting lung perfusion.
Question 4 of 5
The second heart sound (dupp) closely follows which of the events listed below?
Correct Answer: D
Rationale: The second heart sound ('dupp') occurs when semilunar valves (aortic and pulmonary) close, marking the end of ventricular systole as ventricular pressure drops below arterial pressure, halting ejection. Valvular stenosis is a condition, not an event. Semilunar valves opening starts systole, tied to the first sound ('lub') with AV valve closure. AV closing precedes systole, not the second sound. This 'dupp,' sharper and higher-pitched, reflects elastic recoil of closed valves, a key auscultatory marker in the cardiac cycle, critical for timing and diagnosing valve issues like regurgitation.
Question 5 of 5
Which of the following chambers of the heart is surrounded by the thickest layer of myocardium?
Correct Answer: D
Rationale: The left ventricle has the thickest myocardium, up to 1-1.5 cm, pumping against high systemic pressure (~120 mmHg) to the aorta, requiring robust muscle. The right ventricle (~0.3-0.5 cm) handles lower pulmonary pressure (~25 mmHg). Atria, thin-walled (~0.1-0.2 cm), only fill ventricles. This thickness gradient reflects workload left ventricle's force sustains body-wide circulation, key in hypertrophy or failure where it thickens or weakens, a core structural adaptation.