Human respiratory system MCQs With Answer

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This comprehensive guide offers B. Pharm students a focused set of Human respiratory system MCQs with answer to reinforce learning in respiratory anatomy, physiology, pharmacology, and pathophysiology. The questions cover gas exchange, pulmonary ventilation, alveolar-capillary membrane, ventilation-perfusion matching, respiratory pharmacotherapy (bronchodilators, corticosteroids, mucolytics, leukotriene inhibitors), commonly encountered pulmonary diseases such as asthma, COPD, ARDS and pneumonia, and clinically relevant ABG interpretation. Each MCQ is designed to deepen conceptual understanding, improve exam readiness and link drug mechanisms to respiratory function. Targeted for pharmacy undergraduates, these practice questions emphasize mechanisms, drug actions, adverse effects and therapeutic considerations. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which structure is the primary site of gas exchange in the human respiratory system?

  • Nasal cavity
  • Terminal bronchiole
  • Alveolar sacs
  • Trachea

Correct Answer: Alveolar sacs

Q2. The main muscle responsible for quiet inspiration is:

  • Internal intercostals
  • Diaphragm
  • External oblique
  • Sternocleidomastoid

Correct Answer: Diaphragm

Q3. Which law explains the relationship between pressure and volume in the lung during respiration?

  • Henry’s law
  • Boyle’s law
  • Dalton’s law
  • Fick’s law

Correct Answer: Boyle’s law

Q4. Ventilation-perfusion (V/Q) mismatch most commonly leads to which arterial blood gas abnormality?

  • Metabolic alkalosis
  • Hypoxemia with normal CO2
  • Hyperoxemia and hypocapnia
  • Hypocapnia with respiratory alkalosis

Correct Answer: Hypoxemia with normal CO2

Q5. Which cell type produces surfactant in the alveoli?

  • Type I pneumocytes
  • Type II pneumocytes
  • Macrophages
  • Club cells

Correct Answer: Type II pneumocytes

Q6. The primary neurotransmitter mediating bronchoconstriction via parasympathetic activation is:

  • Norepinephrine
  • Dopamine
  • Acetylcholine
  • Epinephrine

Correct Answer: Acetylcholine

Q7. Which receptor subtype is the main target for short-acting bronchodilators used in acute asthma?

  • Beta-1 adrenergic
  • Beta-2 adrenergic
  • M3 muscarinic
  • Alpha-1 adrenergic

Correct Answer: Beta-2 adrenergic

Q8. Which of the following drugs is a leukotriene receptor antagonist used in asthma management?

  • Montelukast
  • Salbutamol
  • Fluticasone
  • Theophylline

Correct Answer: Montelukast

Q9. Diffusion capacity of the lung for carbon monoxide (DLCO) is reduced in which condition?

  • Asthma
  • Emphysema
  • Upper airway obstruction
  • Acute bronchitis

Correct Answer: Emphysema

Q10. Which parameter best reflects the elastic recoil of the lung and chest wall?

  • Tidal volume
  • Residual volume
  • Compliance
  • Vital capacity

Correct Answer: Compliance

Q11. In chronic obstructive pulmonary disease (COPD), the primary airflow limitation is due to:

  • Increased elastic recoil and decreased airway resistance
  • Small airway inflammation and loss of alveolar attachments
  • Excessive surfactant production
  • Hyperventilation causing airway dilation

Correct Answer: Small airway inflammation and loss of alveolar attachments

Q12. Which of the following drugs is a long-acting muscarinic antagonist (LAMA) used in COPD?

  • Ipratropium bromide
  • Tiotropium
  • Albuterol
  • Zafirlukast

Correct Answer: Tiotropium

Q13. The oxyhemoglobin dissociation curve shifts to the right with which of the following changes?

  • Decreased temperature, decreased 2,3-BPG
  • Increased pH (alkalosis)
  • Increased temperature and increased 2,3-BPG
  • Decreased PCO2

Correct Answer: Increased temperature and increased 2,3-BPG

Q14. Alveolar ventilation is most directly increased by changes in which variable?

  • Dead space volume
  • Tidal volume and respiratory rate
  • Hemoglobin concentration
  • Diffusing capacity

Correct Answer: Tidal volume and respiratory rate

Q15. Which of the following best describes acute respiratory distress syndrome (ARDS)?

  • Airway hyperresponsiveness reversible with bronchodilators
  • Diffuse alveolar damage with increased permeability pulmonary edema
  • Isolated pleural effusion without hypoxemia
  • Chronic productive cough for more than 3 months

Correct Answer: Diffuse alveolar damage with increased permeability pulmonary edema

Q16. The mechanism of action of glucocorticoids in asthma primarily involves:

  • Direct bronchodilation via beta-2 agonism
  • Inhibition of inflammatory gene transcription and cytokine production
  • Blocking leukotriene receptors
  • Anticholinergic blockade of M3 receptors

Correct Answer: Inhibition of inflammatory gene transcription and cytokine production

Q17. Which inhaled corticosteroid has high first-pass metabolism minimizing systemic effects?

  • Prednisone
  • Beclomethasone dipropionate
  • Fluticasone propionate
  • Dexamethasone

Correct Answer: Fluticasone propionate

Q18. A pulmonary embolism most commonly causes which immediate physiological effect?

  • Increased alveolar ventilation in affected area
  • Dead space ventilation with hypoxemia
  • Increased DLCO
  • Primary metabolic alkalosis

Correct Answer: Dead space ventilation with hypoxemia

Q19. Which of the following is a mucolytic used to break down sputum viscosity?

  • Guaifenesin
  • N-acetylcysteine
  • Montelukast
  • Theophylline

Correct Answer: N-acetylcysteine

Q20. Theophylline’s primary pharmacologic effect in the airways is due to:

  • Phosphodiesterase inhibition increasing cAMP
  • Direct alpha-adrenergic agonism
  • Mucolytic action on sputum
  • Blockade of leukotriene synthesis

Correct Answer: Phosphodiesterase inhibition increasing cAMP

Q21. During inspiration, intrapulmonary pressure becomes:

  • Greater than atmospheric pressure
  • Equal to atmospheric pressure
  • Less than atmospheric pressure
  • Zero mmHg absolute

Correct Answer: Less than atmospheric pressure

Q22. A right-to-left shunt typically results in which of the following that is not correctable by supplemental O2?

  • Hypocapnia
  • Hypoxemia
  • Hypercapnia corrected by O2
  • Increased DLCO

Correct Answer: Hypoxemia

Q23. Which antibiotic class is preferred for treating typical community-acquired pneumonia in many guidelines for otherwise healthy adults?

  • Aminoglycosides
  • Macrolides
  • Tetracyclines only
  • First-generation cephalosporins

Correct Answer: Macrolides

Q24. Cystic fibrosis arises from a mutation in which protein affecting chloride transport?

  • Na-K ATPase
  • Cystic fibrosis transmembrane conductance regulator (CFTR)
  • ACE enzyme
  • Surfactant protein B

Correct Answer: Cystic fibrosis transmembrane conductance regulator (CFTR)

Q25. Which test is most useful for diagnosing reversible airway obstruction?

  • Chest X-ray
  • Bronchial provocation test
  • Spirometry with bronchodilator response
  • DLCO measurement

Correct Answer: Spirometry with bronchodilator response

Q26. Which gas law describes partial pressures of gases in a mixture?

  • Boyle’s law
  • Henry’s law
  • Dalton’s law
  • Graham’s law

Correct Answer: Dalton’s law

Q27. Beta-2 agonist side effects often include:

  • Bradycardia and hypotension
  • Tremor and tachycardia
  • Dry mouth only
  • Renal failure

Correct Answer: Tremor and tachycardia

Q28. Which adverse effect is most associated with systemic corticosteroid therapy?

  • Hypoglycemia
  • Osteoporosis and hyperglycemia
  • Bradykinesia
  • Hyperkalemia

Correct Answer: Osteoporosis and hyperglycemia

Q29. In obstructive lung disease, which spirometric pattern is typical?

  • Reduced FEV1/FVC ratio
  • Normal FEV1 but reduced TLC
  • Increased FEV1/FVC ratio
  • Isolated reduction in DLCO only

Correct Answer: Reduced FEV1/FVC ratio

Q30. Which immune cell predominates in the airway inflammation of allergic asthma?

  • Neutrophils
  • Eosinophils
  • Basophils only
  • Monocytes

Correct Answer: Eosinophils

Q31. Pulmonary surfactant decreases surface tension primarily by:

  • Increasing alveolar capillary permeability
  • Reducing cohesive forces at the air-liquid interface
  • Stimulating type I pneumocytes to proliferate
  • Activating macrophages

Correct Answer: Reducing cohesive forces at the air-liquid interface

Q32. Which inhaled agent is often used as a rescue medication for acute bronchospasm?

  • Salmeterol
  • Formoterol
  • Salbutamol (albuterol)
  • Fluticasone

Correct Answer: Salbutamol (albuterol)

Q33. The primary chemoreceptors that respond to changes in arterial CO2 are located in:

  • Carotid bodies only
  • Aortic bodies only
  • Medulla oblongata (central chemoreceptors)
  • Alveolar epithelium

Correct Answer: Medulla oblongata (central chemoreceptors)

Q34. Which finding is characteristic of emphysema on physical examination?

  • Productive cough with cyanosis
  • Barrel-shaped chest and decreased breath sounds
  • Fine inspiratory crackles at bases
  • Pertinent hepatomegaly only

Correct Answer: Barrel-shaped chest and decreased breath sounds

Q35. In asthma therapy, omalizumab is an example of:

  • A monoclonal antibody against IgE
  • A leukotriene receptor antagonist
  • An inhaled corticosteroid
  • A long-acting beta agonist

Correct Answer: A monoclonal antibody against IgE

Q36. Which acid-base disturbance is expected in acute hyperventilation?

  • Respiratory acidosis
  • Metabolic acidosis
  • Respiratory alkalosis
  • Metabolic alkalosis

Correct Answer: Respiratory alkalosis

Q37. Which of the following promotes unloading of O2 from hemoglobin in peripheral tissues?

  • Decreased temperature and increased pH
  • Increased 2,3-BPG and increased temperature
  • Lower PCO2 and decreased temperature
  • High arterial PO2 only

Correct Answer: Increased 2,3-BPG and increased temperature

Q38. Dornase alfa is used in cystic fibrosis primarily to:

  • Inhibit bacterial cell wall synthesis
  • Hydrolyze extracellular DNA in sputum to reduce viscosity
  • Act as a bronchodilator
  • Block CFTR function

Correct Answer: Hydrolyze extracellular DNA in sputum to reduce viscosity

Q39. Which parameter is decreased in restrictive lung disease?

  • TLC (total lung capacity)
  • FEV1/FVC ratio
  • Residual volume only increases
  • Airway resistance primarily

Correct Answer: TLC (total lung capacity)

Q40. In the context of inhaled drug delivery, particle size most important for deposition in small airways is approximately:

  • Greater than 10 micrometers
  • 5–10 micrometers
  • 1–5 micrometers
  • Less than 0.1 micrometers

Correct Answer: 1–5 micrometers

Q41. Which of the following is the most common cause of community-acquired pneumonia?

  • Pseudomonas aeruginosa
  • Streptococcus pneumoniae
  • Staphylococcus epidermidis
  • Mycobacterium tuberculosis

Correct Answer: Streptococcus pneumoniae

Q42. Which statement about inhaled versus systemic corticosteroids is true?

  • Inhaled steroids have no systemic absorption
  • Inhaled steroids reduce airway inflammation with lower systemic side effects compared to oral steroids
  • Systemic steroids are always safer than inhaled steroids
  • Inhaled steroids directly block beta receptors

Correct Answer: Inhaled steroids reduce airway inflammation with lower systemic side effects compared to oral steroids

Q43. Which physiological response improves oxygenation in regions of low ventilation?

  • Hypoxic pulmonary vasoconstriction redirecting blood flow
  • Bronchodilation of poorly ventilated alveoli
  • Increased alveolar surfactant production
  • Systemic vasodilation

Correct Answer: Hypoxic pulmonary vasoconstriction redirecting blood flow

Q44. Which drug class reduces mucus production and is used in COPD exacerbations as adjunct therapy?

  • Antitussives
  • Mucolytics and expectorants
  • Leukotriene inhibitors only
  • ACE inhibitors

Correct Answer: Mucolytics and expectorants

Q45. A patient on theophylline develops nausea, tachycardia and seizures; this most likely reflects:

  • Therapeutic drug effect at normal levels
  • Acetaminophen interaction
  • Theophylline toxicity due to narrow therapeutic index
  • Allergic reaction to theophylline

Correct Answer: Theophylline toxicity due to narrow therapeutic index

Q46. In obstructive sleep apnea, which factor primarily leads to airflow obstruction during sleep?

  • Bronchial smooth muscle constriction
  • Collapse of the upper airway due to reduced muscle tone
  • Pulmonary embolism
  • Excessive surfactant

Correct Answer: Collapse of the upper airway due to reduced muscle tone

Q47. Which laboratory measurement best indicates oxygen-carrying capacity of blood?

  • PaO2
  • SaO2 only
  • Hemoglobin concentration
  • DLCO

Correct Answer: Hemoglobin concentration

Q48. In bacterial pneumonia, which sign is most specific for consolidation on lung auscultation?

  • Wheezing
  • Crackles and bronchial breath sounds
  • Diffuse diminished breath sounds bilaterally
  • Pleural friction rub only

Correct Answer: Crackles and bronchial breath sounds

Q49. Which therapy is recommended for influenza to reduce duration of illness if started early?

  • Oseltamivir (neuraminidase inhibitor)
  • Amoxicillin
  • Prednisone
  • Azithromycin

Correct Answer: Oseltamivir (neuraminidase inhibitor)

Q50. Which feature distinguishes pulmonary arterial hypertension from other causes of dyspnea?

  • Elevated pulmonary artery pressures with right ventricular hypertrophy
  • Low pulmonary artery pressure and increased DLCO
  • Predominant upper airway obstruction signs
  • Isolated alveolar hypoventilation without vascular change

Correct Answer: Elevated pulmonary artery pressures with right ventricular hypertrophy

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