Free Respiratory System MCQs with Answers

• A. Exchange oxygen and carbon dioxide
• B. Warm, filter and humidify inspired air
• C. Produce red blood cells in the lungs
• D. Store oxygen for use during exercise

Explanation: The conducting passages move air toward the respiratory zone while warming, filtering and humidifying it.

• A. Place the patient flat and offer oral fluids
• B. Apply high-flow oxygen and activate emergency help
• C. Encourage coughing and deep-breathing exercises
• D. Obtain a routine sputum specimen for culture

Explanation: These findings suggest a tension pneumothorax, which severely impairs breathing and circulation.

• A. The diaphragm relaxes and moves upward
• B. Thoracic volume decreases and pressure rises
• C. The diaphragm contracts and moves downward
• D. The lungs compress and push air outward

Explanation: During inspiration, the diaphragm contracts and flattens, increasing thoracic volume.

• A. Exchange of gases between blood and body tissues
• B. Exchange of gases between alveoli and pulmonary blood
• C. Use of oxygen by cells to produce cellular energy
• D. Movement of air between the atmosphere and alveoli

Explanation: External respiration is the exchange of oxygen and carbon dioxide between alveolar air and pulmonary capillary blood.

• A. Open the airway and assess breathing immediately
• B. Offer water and ask the patient to walk
• C. Document the sedation and reassess after one hour
• D. Place the patient in a quiet room to promote sleep

Explanation: Marked sedation and slow breathing indicate possible opioid-induced respiratory depression.

• A. Dissolved freely in the plasma
• B. Attached to haemoglobin in red blood cells
• C. Combined with bicarbonate ions in plasma
• D. Stored inside the alveolar air spaces

Explanation: Most oxygen binds reversibly to haemoglobin, forming oxyhaemoglobin. Only a small amount is dissolved directly in plasma; bicarbonate is…

• A. Mucus
• B. Surfactant
• C. Bicarbonate
• D. Haemoglobin

Explanation: Surfactant reduces surface tension inside the alveoli and helps keep them open, especially during expiration.

• A. Most carbon dioxide travels as bicarbonate ions
• B. Most carbon dioxide remains trapped in the alveoli
• C. Carbon dioxide binds only to white blood cells
• D. Carbon dioxide is transported mainly as free gas bubbles

Explanation: Most carbon dioxide is converted to bicarbonate ions and carried in plasma.

• A. A fall in blood glucose
• B. An increase in hydrogen ion concentration
• C. An increase in plasma calcium
• D. A rise in body temperature alone

Explanation: Raised carbon dioxide forms carbonic acid, increasing hydrogen ions in cerebrospinal fluid and stimulating the medullary respiratory…

• A. Digest particles entering the bronchi
• B. Reduce friction during lung movement
• C. Carry oxygen from alveoli to tissues
• D. Produce surfactant inside the alveoli

Explanation: A thin layer of pleural fluid lubricates the pleural surfaces and allows the lungs to move smoothly during breathing.

• A. 500 mL per breath
• B. 1,000 mL per breath
• C. 1,500 mL per breath
• D. 2,000 mL per breath

Explanation: Tidal volume is the amount of air moved in or out during one quiet breath, and it is about 500 mL in a healthy adult.

• A. It is wider and more vertical
• B. It is narrower and more horizontal
• C. It is longer and more curved
• D. It is closed during swallowing

Explanation: The right main bronchus is wider, shorter and more vertical than the left main bronchus, so aspirated material more often enters it.

• A. Simple diffusion
• B. Active transport
• C. Facilitated diffusion
• D. Osmosis

Explanation: Respiratory gases cross the thin alveolar-capillary membrane by simple diffusion down their partial-pressure gradients.

• A. Increased diffusion distance
• B. Increased red blood cell count
• C. Reduced airway resistance
• D. Increased pleural pressure

Explanation: Thickened alveolar walls increase the distance that oxygen must cross, so diffusion into pulmonary capillaries becomes less efficient.

• A. It promotes oxygen release to tissues
• B. It prevents oxygen release to tissues
• C. It increases haemoglobin production immediately
• D. It causes oxygen to bind more strongly

Explanation: A fall in pH shifts the oxyhaemoglobin dissociation curve to the right, allowing haemoglobin to release more oxygen to metabolically…

• A. I inhale slowly through the mouthpiece
• B. I exhale forcefully into the mouthpiece
• C. I use it only when I feel breathless
• D. I take rapid shallow breaths into it

Explanation: The patient should seal the lips around the mouthpiece and inhale slowly and deeply to raise the indicator.

• A. Assess the tube for obstruction
• B. Offer oral fluids to loosen secretions
• C. Place the patient flat in bed
• D. Document the change in the chart

Explanation: The findings indicate an immediate airway and breathing emergency, so the nurse first assesses the tracheostomy tube and removes…

• A. The maximum air exhaled after maximum inhalation
• B. The air remaining after maximum exhalation
• C. The air moved during one quiet breath
• D. The total air in the lungs after normal inhalation

Explanation: Vital capacity is the greatest volume exhaled after a person inhales as deeply as possible.

• A. Peripheral chemoreceptors
• B. Stretch receptors
• C. Baroreceptors
• D. Pain receptors

Explanation: Peripheral chemoreceptors in the carotid and aortic bodies respond especially to low arterial oxygen and also to changes in carbon dioxide…

• A. Oxygen moves into cells and carbon dioxide enters blood
• B. Oxygen enters alveoli and carbon dioxide leaves blood
• C. Nitrogen moves into cells and oxygen enters alveoli
• D. Carbon dioxide leaves cells and oxygen leaves blood

Explanation: During internal respiration, tissue cells use oxygen, so oxygen diffuses from systemic blood into cells and carbon dioxide diffuses from…