QCM : Respiratory Physiology and Diagnostics — 30 questions

Explication

Cough and dyspnea are the cardinal symptoms of respiratory-system disease. The other options describe findings that may occur but are not the core cardinal symptoms.

Explication

Air hunger or a sense of suffocation points toward congestive heart failure as a non-pulmonary cause of dyspnea. Chest tightness/inability to take a deep breath fits obstructive lung disease instead.

Explication

In this classification, a cough lasting 3–4 weeks is subacute. The “acute” category is under 3 weeks, and “chronic” is more than 8 weeks.

Explication

Wheezing suggests airway disease such as asthma or COPD. Stridor, not wheezing, suggests upper-airway obstruction.

Explication

The conducting zone transports gas but does not perform gas exchange, forming an anatomic dead space of about 150 mL. Gas exchange occurs in the respiratory zone, not the conducting zone.

Explication

The respiratory zone consists of the respiratory bronchioles, alveolar ducts, and alveolar sacs, which are the gas-exchange region. The conducting zone includes parts of the pathway but is not the primary gas-exchange site.

Explication

Type I pneumocytes cover about 96–98% of the alveolar surface area and are responsible for gas exchange. Type II pneumocytes are the smaller fraction and produce surfactant.

Explication

The lungs have a dual blood supply consisting of pulmonary circulation and bronchial circulation. The other options incorrectly describe the lung blood supply as single-source or absent.

Explication

Pulmonary circulation sends deoxygenated blood to the respiratory bronchioles/alveolar region and returns it to the left atrium via pulmonary veins. Bronchial circulation supplies conducting airways and returns primarily via bronchial veins.

Explication

Bronchial circulation provides oxygenated blood to the conducting airways and surrounding tissues, can undergo angiogenesis, and receives about 1–2% of cardiac output. Pulmonary circulation is responsible for the gas-exchange region and for returning blood to the left atrium via pulmonary veins.

Explication

Successful oxygenation and carbon-dioxide elimination require ventilation, perfusion, and diffusion. If any one component is missing, gas transfer cannot proceed effectively.

Explication

The four basic lung volumes are inspiratory reserve volume, tidal volume, expiratory reserve volume, and residual volume.

Explication

Lung capacities combine two or more lung volumes, while lung volumes are single measured compartments. The distractor reverses this relationship.

Explication

Spirometry is a physiological test that measures inhaled and exhaled air volumes as a function of time, using volume or flow as the primary signal.

Explication

Forced vital capacity is the volume delivered during a forced, complete expiration after full inspiration. The distractors describe quiet breathing, residual volume, or FEV1 instead.

Explication

Obstruction is due to hindrance to airflow and is characterized by decreased airflow and a decreased FEV1/FVC ratio. The distractors describe restriction or diffusion-focused problems.

Explication

Restriction requires reduced lung volume, including reduced total lung capacity; low FVC alone is not enough. The distractors misuse other measures that do not establish restriction by themselves.

Explication

FEV1/FVC is considered low when it is less than 70%. The distractors are incorrect thresholds.

Explication

Because gas equilibrates near the beginning of the capillary in perfusion-limited exchange, additional transfer increases mainly by increasing blood flow. The distractors confuse other limits or unrelated concepts.

Explication

Diffusion-limited exchange means gas does not equilibrate by the end of the pulmonary capillary. The distractors describe equilibration early or guaranteed equilibration.

Explication

Wasted ventilation is ventilation of unperfused lung (e.g., distal to a pulmonary embolism). A shunt is perfused but non-ventilated.

Explication

Idiopathic pulmonary fibrosis is associated with increased elastic recoil, reduced lung volumes, normal airway resistance, reduced diffusing capacity, and low oxygenation. The distractors fit other patterns such as emphysema or acute asthma.

Explication

Routine chest radiography includes posteroanterior, lateral, and lateral-decubitus views. The other options omit one of these routine views.

Explication

Ultrasound is non-ionizing and may guide thoracentesis and biopsy of peripheral lung, pleural, and chest-wall lesions. CT instead uses ionizing radiation, making it a different safety profile.

Explication

Contrast in CT helps distinguish vascular from non-vascular structures. CT also assesses mediastinal/hilar disease and can be adapted for interstitial lung disease, so the other choices are incorrect.

Explication

False positives on PET can occur with pneumonia and granulomatous disease because increased uptake is not specific for malignancy. Tumor size and normal tissue uptake are not the described reasons.

Explication

Thoracentesis has both diagnostic and therapeutic purposes, and it may be ultrasound guided. The other options incorrectly restrict it to a single purpose.

Explication

Bronchoscopy directly visualizes the tracheobronchial tree and has both diagnostic and therapeutic purposes. Sputum induction and pleural techniques do not provide direct visualization of the tracheobronchial tree.

Explication

Medical thoracoscopy is performed under conscious sedation and local anesthesia, with inspection of the pleural surface and pleural biopsy/drainage capability. The distractors incorrectly substitute general anesthesia or omit local anesthesia.

Explication

Thoracotomy provides a larger biopsy sample and allows excision of lesions that are too deep or too close to vital structures for removal by VATS. The other options contradict this comparison or misstate the indications.