MCQ 51:
Which of the following is a long-term effect of smoking on the respiratory system?
A) Improved lung function
B) Increased lung elasticity
C) Chronic obstructive pulmonary disease (COPD)
D) Enhanced gas exchange
Answer: C) Chronic obstructive pulmonary disease (COPD)
Explanation: Smoking is a major risk factor for developing COPD, which includes conditions like chronic bronchitis and emphysema.
MCQ 52:
Which of the following changes occurs during deep inhalation?
A) Diaphragm relaxes
B) Intercostal muscles relax
C) Thoracic cavity volume decreases
D) Thoracic cavity volume increases
Answer: D) Thoracic cavity volume increases
Explanation: During deep inhalation, the diaphragm contracts and the intercostal muscles elevate the ribs, increasing thoracic cavity volume.
MCQ 53:
The primary role of the respiratory system in thermoregulation is to:
A) Control blood pressure
B) Regulate body temperature through breathing
C) Maintain pH balance
D) Filter toxins
Answer: B) Regulate body temperature through breathing
Explanation: The respiratory system helps regulate body temperature by facilitating heat exchange with the environment through breathing.
MCQ 54:
Which gas law explains the relationship between the pressure and volume of gases in the lungs?
A) Dalton’s law
B) Henry’s law
C) Boyle’s law
D) Charles’s law
Answer: C) Boyle’s law
Explanation: Boyle’s law states that the pressure of a gas is inversely related to its volume at constant temperature, applicable to lung mechanics during inhalation and exhalation.
MCQ 55:
What occurs during external respiration?
A) Gas exchange between blood and tissues
B) Gas exchange between the lungs and blood
C) Cellular respiration
D) Metabolic processes in cells
Answer: B) Gas exchange between the lungs and blood
Explanation: External respiration refers to the exchange of oxygen and carbon dioxide between the lungs and the bloodstream.
MCQ 56:
What is the significance of the pulmonary surfactant?
A) It transports oxygen in the blood.
B) It increases surface tension in the alveoli.
C) It prevents alveolar collapse.
D) It acts as a barrier to pathogens.
Answer: C) It prevents alveolar collapse.
Explanation: Pulmonary surfactant reduces surface tension in the alveoli, preventing them from collapsing during exhalation.
MCQ 57:
The term “hypercapnia” refers to:
A) Low levels of oxygen
B) High levels of carbon dioxide
C) High levels of nitrogen
D) Low levels of carbon dioxide
Answer: B) High levels of carbon dioxide
Explanation: Hypercapnia is the condition characterized by an excess of carbon dioxide in the bloodstream.
MCQ 58:
Which respiratory condition is characterized by a “hacking” cough and mucus production?
A) Asthma
B) Chronic bronchitis
C) Emphysema
D) Pneumonia
Answer: B) Chronic bronchitis
Explanation: Chronic bronchitis is marked by a persistent cough with mucus production due to inflammation of the bronchial tubes.
MCQ 59:
Which type of lung volume represents the total amount of air the lungs can hold?
A) Tidal volume
B) Vital capacity
C) Total lung capacity
D) Residual volume
Answer: C) Total lung capacity
Explanation: Total lung capacity is the maximum amount of air the lungs can hold, including all volumes (tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume).
MCQ 60:
What is the primary stimulus for the body to initiate breathing?
A) Low oxygen levels
B) High carbon dioxide levels
C) High blood pressure
D) Low blood sugar
Answer: B) High carbon dioxide levels
Explanation: The primary driver for the urge to breathe is the concentration of carbon dioxide in the blood; high levels stimulate the respiratory centers in the brain.
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