Questions of Respiratory System

Questions of Respiratory System Related

Review Questions of Respiratory System related questions and content

During one circuit of blood from lungs to the tissue and back through the circulatory system the percentage of haemoglobin giving the oxygen is

  • A. 50%
  • B. 25%
  • C. 75%
  • D. 100%
Correct Answer: B

Rationale: The correct answer is B (25%). In the lungs, oxygen binds to hemoglobin to form oxyhemoglobin. This increases the oxygen saturation of hemoglobin to around 97-98%. As blood travels to the tissues, oxygen is released from hemoglobin to be used by the cells. By the time blood returns to the lungs, only about 25% of the hemoglobin is still carrying oxygen. This is known as the oxygen saturation curve. Choice A (50%) is incorrect because the percentage of hemoglobin carrying oxygen drops significantly as blood travels to the tissues. Choice C (75%) is incorrect because by the time blood returns to the lungs, more than 25% of the hemoglobin has already released its oxygen. Choice D (100%) is incorrect because not all hemoglobin molecules carry oxygen at the same time; it depends on the oxygen tension in the environment.

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What is the primary principle involved in the various airway clearance devices used for mobilizing secretions?

  • A. Vibration
  • B. Inhalation therapy
  • C. Chest physiotherapy
  • D. Positive expiratory pressure
Correct Answer: D

Rationale: The primary principle involved in airway clearance devices used for mobilizing secretions is positive expiratory pressure, which helps in loosening and moving mucus from the airways.

The impulse for voluntary muscles for forceful breathing starts in

  • A. Medulla (Pons)
  • B. Vagus nerve
  • C. Cerebral hemispheres
  • D. Spinal cord
Correct Answer: C

Rationale: The correct answer is C: Cerebral hemispheres. The impulse for voluntary muscles for forceful breathing originates in the cerebral hemispheres where conscious control over breathing is regulated. The cerebral cortex sends signals to the respiratory muscles to increase or decrease breathing effort based on the body's needs. The other choices are incorrect because:
A: Medulla (Pons) - This region of the brainstem is responsible for automatic breathing control, not voluntary forceful breathing.
B: Vagus nerve - The vagus nerve is not directly involved in initiating voluntary breathing movements.
D: Spinal cord - While the spinal cord plays a role in coordinating some aspects of breathing, it is not the primary center for voluntary forceful breathing control.

diaphragm relaxes and decrease thoracic space in which phase of respiration.

  • A. inspiration
  • B. expiration
  • C. Pause
  • D. both a and b
Correct Answer: B

Rationale: During expiration, the diaphragm relaxes, causing it to move upwards, which decreases the thoracic space. This leads to the expulsion of air from the lungs. In contrast, during inspiration, the diaphragm contracts and moves downwards, increasing the thoracic space to allow air to enter the lungs. Option C, Pause, does not involve any specific respiratory phase. Option D, both a and b, is incorrect because during inspiration, the diaphragm contracts and increases thoracic space. Therefore, the correct answer is B, expiration, as this phase specifically involves the relaxation of the diaphragm and the decrease in thoracic space.

Reduction in respiratory surface of the lungs due to break down of partition in the alveoli is known as

  • A. Asphyxia
  • B. Bronchitis
  • C. Asthma
  • D. Emphysema
Correct Answer: D

Rationale: Emphysema is the correct answer because it is a condition where the alveoli walls break down, reducing the surface area for gas exchange in the lungs. This leads to difficulty in breathing. Asphyxia is suffocation due to lack of oxygen, not related to alveoli breakdown. Bronchitis is inflammation of the bronchial tubes, not alveoli damage. Asthma is a chronic condition affecting the airways, not specifically related to alveoli destruction. Therefore, emphysema is the most appropriate term for reduction in respiratory surface due to alveolar breakdown.

Hemoglobin's affinity for oxygen when the BPG level is high is

  • A. greater than hemoglobin's affinity for oxygen when the BPG level is low
  • B. less than hemoglobin's affinity for oxygen when the BPG level is low
  • C. equal to hemoglobin's affinity for oxygen when the BPG level is low
  • D. equal to hemoglobin's affinity for oxygen when pH is low
Correct Answer: B

Rationale: The correct answer is B: less than hemoglobin's affinity for oxygen when the BPG level is low. When the 2,3-bisphosphoglycerate (BPG) level is high, it binds to hemoglobin and decreases its affinity for oxygen. This results in easier unloading of oxygen to tissues. In contrast, when the BPG level is low, hemoglobin's affinity for oxygen is higher, making it harder to release oxygen to tissues. Choices A and C are incorrect because high BPG levels decrease hemoglobin's affinity for oxygen, making it less than when BPG levels are low. Choice D is incorrect because pH levels do not directly affect hemoglobin's affinity for oxygen in the context of this question.

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