MCQs G12 C3 Human Respiratory System

MCQs on the Human Respiratory System

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1. 1. When blood leaves the capillary bed, most of the carbon dioxide is in the form of:

   • A. carbonate ions
   • B. hydrogen ions
   • C. bicarbonate ions
   • D. hydroxyl ions

   Answer: C. bicarbonate ions

2. 2. When you inhale, the diaphragm:

   • A. relaxes and moves upward
   • B. contracts and moves downward
   • C. contracts and moves upward
   • D. relaxes and moves downward

   Answer: B. contracts and moves downward

3. 3. With which other system do specialised respiratory systems most closely interface in exchanging gases between the cells and the environment?

   • A. the skin
   • B. the excretory system
   • C. the circulatory system
   • D. the muscular system

   Answer: C. the circulatory system

4. 4. Which of the following is the respiratory surface in the human respiratory system?

   • A. larynx
   • B. trachea
   • C. bronchi
   • D. alveoli

   Answer: D. alveoli

5. 5. How is most of the oxygen transported in the blood?

   • A. dissolved in plasma
   • B. bound to haemoglobin
   • C. as bicarbonate
   • D. dissolved in water

   Answer: B. bound to haemoglobin

6. 6. The lateral walls of the chest cavity of man are composed of the:

   • A. ribs
   • B. intercostal muscles
   • C. ribs and intercostal muscles
   • D. ribs, intercostal muscles and diaphragm

   Answer: D. ribs, intercostal muscles and diaphragm

7. 7. Which of the following factors is the most effective in accelerating the rate of breathing in man?

   • A. A lack of oxygen in the blood
   • B. A lack of oxygen in the tissues
   • C. An excess of carbon dioxide in the lungs
   • D. An excess of carbon dioxide in the blood

   Answer: D. An excess of carbon dioxide in the blood

8. 8. Which of the following changes will increase the body's rate of carbon dioxide excretion into the alveoli?

   • A. holding the breath
   • B. the breakdown of alveolar tissue as a result of disease
   • C. a decrease in the partial pressure of carbon dioxide in the alveolar air
   • D. a decrease in the pulmonary circulation

   Answer: C. a decrease in the partial pressure of carbon dioxide in the alveolar air

9. 9. Breathing is an example of:

   • A. counter current exchange
   • B. cellular respiration
   • C. ventilation
   • D. diffusion

   Answer: C. ventilation

10. 10. Which sequence most accurately describes the sequence of airflow in the human respiratory system?

    • A. pharynx -> bronchus -> trachea -> larynx -> alveolus -> bronchiole
    • B. pharynx -> larynx -> trachea -> bronchus -> bronchiole -> alveolus
    • C. trachea -> larynx -> pharynx -> bronchus -> bronchiole -> alveolus
    • D. larynx -> pharynx -> trachea -> bronchus -> alveolus -> bronchiole

    Answer: B. pharynx -> larynx -> trachea -> bronchus -> bronchiole -> alveolus

11. 11. Which one of the following changes takes place during inspiration?

    • A. Decrease in thoracic cavity
    • B. Decrease in diaphragm
    • C. Relaxation in external intercostal muscles
    • D. Sternum moves towards ventral and anterior direction

    Answer: D. Sternum moves towards ventral and anterior direction

12. 12. The volume of air that can be exhaled after normal exhalation is the:

    • A. tidal volume
    • B. residual volume
    • C. inspiratory reserve volume
    • D. expiratory reserve volume

    Answer: D. expiratory reserve volume

13. 13. Hemoglobin:

    • A. combine reversely with only oxygen
    • B. attach to the alveolar wall
    • C. all have four heme group
    • D. none of them

    Answer: A. combine reversely with only oxygen

14. 14. The maximum volume of air contained in the lung by a full forced inhalation is called:

    • A. Tidal volume
    • B. Vital capacity
    • C. Ventilation rate
    • D. Total lung capacity

    Answer: D. Total lung capacity

15. 15. Dissociation of O₂ from oxyhaemoglobin is facilitated by:

    • A. decreased temperature
    • B. decreased PO₂
    • C. decreased H+
    • D. exercise

    Answer: B. decreased PO₂

16. 16. Which of these correctly orders the structures through which air passes during inhalation?

    • A. pharynx -> trachea -> larynx -> bronchi
    • B. pharynx -> larynx -> trachea -> bronchi
    • C. larynx -> pharynx -> bronchi -> trachea
    • D. larynx -> pharynx -> trachea -> bronchi

    Answer: B. pharynx -> larynx -> trachea -> bronchi

17. 17. The pharynx is also known as the:

    • A. windpipe
    • B. trachea
    • C. voice box
    • D. throat

    Answer: D. throat

18. 18. What is the correct path air takes when it enters the trachea on its way to the lungs?

    • A. bronchi -> bronchioles -> pulmonary capillaries -> alveoli
    • B. bronchioles -> bronchi -> alveoli -> pulmonary capillaries
    • C. bronchi -> pulmonary capillaries -> alveoli -> bronchioles
    • D. bronchi -> bronchioles -> alveoli -> pulmonary capillaries

    Answer: D. bronchi -> bronchioles -> alveoli -> pulmonary capillaries

19. 19. Which of the following is correct for the partial pressure of oxygen in alveoli?

    • A. less than carbon dioxide
    • B. less than the blood
    • C. more than the blood
    • D. equal to that of the blood

    Answer: C. more than the blood

20. 20. Which of the following is the respiratory surface in human respiratory system?

    • A. larynx
    • B. trachea
    • C. bronchi
    • D. alveoli

    Answer: D. alveoli

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