Part 7: Regulation of Respiration (25 MCQs)

Q1. The respiratory rhythm centre is located in:

A. Cerebrum
B. Hypothalamus
C. Medulla oblongata
D. Cerebellum

Answer: C

Explanation:

A. Incorrect: Cerebrum controls voluntary respiration only.
B. Incorrect: Hypothalamus regulates autonomic functions, not direct rhythm.
C. Correct: Medullary respiratory centre sets basic rhythm of breathing.
D. Incorrect: Cerebellum controls coordination, not respiration.

Q2. The pneumotaxic centre is located in:

A. Cerebrum
B. Pons
C. Medulla
D. Midbrain

Answer: B

Explanation:

A. Incorrect: Cerebrum gives voluntary control.
B. Correct: Pneumotaxic centre in pons regulates rate of breathing.
C. Incorrect: Medulla has rhythm centre, not pneumotaxic.
D. Incorrect: Midbrain not directly involved.

Q3. Which part of brain is responsible for voluntary control of breathing (e.g., holding breath)?

A. Medulla oblongata
B. Pons
C. Cerebral cortex
D. Hypothalamus

Answer: C

Explanation:

A. Incorrect: Medulla controls involuntary rhythm.
B. Incorrect: Pons modifies rate, not voluntary control.
C. Correct: Cortex allows voluntary actions like breath-holding, singing.
D. Incorrect: Hypothalamus influences indirectly.

Q4. Which chemical factor is the strongest regulator of respiration?

A. pO₂
B. pCO₂
C. pH only
D. Temperature

Answer: B

Explanation:

A. Incorrect: O₂ has lesser influence unless very low.
B. Correct: CO₂ levels (via H⁺) are primary drivers.
C. Incorrect: pH changes are secondary to CO₂.
D. Incorrect: Temperature minor influence.

Q5. Peripheral chemoreceptors sensitive to O₂ are located in:

A. Carotid bodies and aortic bodies
B. Medulla oblongata
C. Lungs
D. Diaphragm

Answer: A

Explanation:

A. Correct: Carotid and aortic bodies detect low pO₂.
B. Incorrect: Medulla senses pCO₂/pH.
C. Incorrect: Lungs have stretch receptors, not O₂ sensors.
D. Incorrect: Diaphragm is muscle, not receptor.

Q6. Central chemoreceptors are mainly sensitive to:

A. O₂
B. CO₂ and H⁺ in CSF
C. N₂
D. Temperature

Answer: B

Explanation:

A. Incorrect: O₂ detected peripherally.
B. Correct: Central chemoreceptors respond to pCO₂/H⁺ in cerebrospinal fluid.
C. Incorrect: N₂ not regulated.
D. Incorrect: Temperature not direct factor.

Q7. Which nerve carries impulses from carotid bodies to the respiratory centre?

A. Vagus nerve
B. Glossopharyngeal nerve
C. Phrenic nerve
D. Intercostal nerve

Answer: B

Explanation:

A. Incorrect: Vagus carries aortic body signals.
B. Correct: Glossopharyngeal nerve carries carotid body signals.
C. Incorrect: Phrenic nerve supplies diaphragm.
D. Incorrect: Intercostal nerves supply muscles.

Q8. Which nerve carries signals from aortic bodies?

A. Phrenic
B. Vagus
C. Glossopharyngeal
D. Hypoglossal

Answer: B

Explanation:

A. Incorrect: Phrenic is motor to diaphragm.
B. Correct: Vagus nerve transmits signals from aortic bodies.
C. Incorrect: Glossopharyngeal carries carotid body signals.
D. Incorrect: Hypoglossal supplies tongue muscles.

Q9. Stretch receptors in lungs prevent over-inflation by initiating:

A. Bohr effect
B. Haldane effect
C. Hering-Breuer reflex
D. Chloride shift

Answer: C

Explanation:

A. Incorrect: Bohr effect = CO₂ influence on O₂ transport.
B. Incorrect: Haldane effect = O₂ influence on CO₂ transport.
C. Correct: Hering-Breuer reflex inhibits inspiration to prevent over-inflation.
D. Incorrect: Chloride shift relates to CO₂ transport.

Q10. The Hering-Breuer reflex is mediated by:

A. Phrenic nerve
B. Glossopharyngeal nerve
C. Vagus nerve
D. Spinal nerves

Answer: C

Explanation:

A. Incorrect: Phrenic controls diaphragm contraction.
B. Incorrect: Glossopharyngeal conveys carotid signals.
C. Correct: Vagus nerve transmits stretch receptor signals.
D. Incorrect: Spinal nerves not involved.

Q11. Hypercapnia refers to:

A. Low blood O₂
B. High blood CO₂
C. Low blood CO₂
D. High blood O₂

Answer: B

Explanation:

A. Incorrect: That is hypoxemia.
B. Correct: Hypercapnia = elevated CO₂ in blood.
C. Incorrect: Low CO₂ = hypocapnia.
D. Incorrect: High O₂ = hyperoxia.

Q12. Hypoxia refers to:

A. Low pO₂ in tissues
B. High pCO₂ in blood
C. Low pH in blood
D. Increased Hb

Answer: A

Explanation:

A. Correct: Hypoxia = deficiency of O₂ in tissues.
B. Incorrect: That is hypercapnia.
C. Incorrect: Low pH = acidosis.
D. Incorrect: High Hb is polycythemia.

Q13. Which type of hypoxia occurs at high altitude?

A. Hypoxic hypoxia
B. Anemic hypoxia
C. Histotoxic hypoxia
D. Stagnant hypoxia

Answer: A

Explanation:

A. Correct: Low atmospheric O₂ → hypoxic hypoxia.
B. Incorrect: Anemia due to less Hb.
C. Incorrect: Histotoxic hypoxia = cyanide poisoning.
D. Incorrect: Stagnant hypoxia = poor circulation.

Q14. In carbon monoxide poisoning, which type of hypoxia develops?

A. Hypoxic hypoxia
B. Anemic hypoxia
C. Histotoxic hypoxia
D. Stagnant hypoxia

Answer: B

Explanation:

A. Incorrect: Atmospheric O₂ is normal.
B. Correct: CO binds Hb, reducing O₂ carrying capacity → anemic hypoxia.
C. Incorrect: Histotoxic occurs when cells can’t use O₂.
D. Incorrect: Stagnant due to circulatory issues.

Q15. Cyanide poisoning causes:

A. Hypoxic hypoxia
B. Anemic hypoxia
C. Histotoxic hypoxia
D. Stagnant hypoxia

Answer: C

Explanation:

A. Incorrect: O₂ is present.
B. Incorrect: Hb levels normal.
C. Correct: Cells cannot utilize O₂ (cytochrome inhibition).
D. Incorrect: Circulation normal.

Q16. Stagnant hypoxia occurs due to:

A. Low atmospheric O₂
B. Low Hb concentration
C. Poor circulation of blood
D. Cellular inability to use O₂

Answer: C

Explanation:

A. Incorrect: That’s hypoxic hypoxia.
B. Incorrect: That’s anemic hypoxia.
C. Correct: Stagnant hypoxia = reduced blood flow (e.g., heart failure).
D. Incorrect: That’s histotoxic.

Q17. Which condition is the strongest stimulus for increasing respiratory rate?

A. Hypoxemia
B. Hypercapnia
C. High blood pressure
D. High temperature

Answer: B

Explanation:

A. Incorrect: Low O₂ weaker stimulus.
B. Correct: High CO₂ (hypercapnia) is strongest respiratory drive.
C. Incorrect: Blood pressure not direct stimulus.
D. Incorrect: Temperature plays a minor role.

Q18. The main function of pneumotaxic centre is to:

A. Initiate inspiration
B. Initiate expiration
C. Control rate of breathing
D. Maintain blood pH

Answer: C

Explanation:

A. Incorrect: Inspiration initiated by medulla.
B. Incorrect: Expiration is passive normally.
C. Correct: Pneumotaxic centre regulates frequency of breaths.
D. Incorrect: Blood pH is indirect effect.

Q19. Which receptor type responds to irritants in airways?

A. Baroreceptors
B. Stretch receptors
C. Chemoreceptors
D. Irritant receptors

Answer: D

Explanation:

A. Incorrect: Baroreceptors detect pressure.
B. Incorrect: Stretch receptors prevent over-inflation.
C. Incorrect: Chemoreceptors detect gases.
D. Correct: Irritant receptors trigger coughing, sneezing.

Q20. Which reflex causes cessation of breathing during swallowing?

A. Hering-Breuer reflex
B. Apneustic reflex
C. Deglutition apnoea
D. Baroreceptor reflex

Answer: C

Explanation:

A. Incorrect: Prevents lung over-inflation.
B. Incorrect: Apneustic centre stimulates inspiration.
C. Correct: Deglutition apnoea stops breathing briefly during swallowing.
D. Incorrect: Baroreceptor reflex controls BP.

Q21. Acclimatization at high altitude involves:

A. Decreased RBC count
B. Increased 2,3-BPG in RBCs
C. Decreased ventilation
D. Decreased Hb concentration

Answer: B

Explanation:

A. Incorrect: RBC count increases.
B. Correct: 2,3-BPG rises → easier O₂ unloading in tissues.
C. Incorrect: Ventilation increases, not decreases.
D. Incorrect: Hb increases, not decreases.

Q22. The apneustic centre is located in:

A. Medulla
B. Pons
C. Cerebrum
D. Hypothalamus

Answer: B

Explanation:

A. Incorrect: Medulla has rhythm centre.
B. Correct: Apneustic centre in pons promotes prolonged inspiration.
C. Incorrect: Cerebrum controls voluntary breathing.
D. Incorrect: Hypothalamus not direct centre.

Q23. Which condition increases respiratory rate most effectively?

A. High blood O₂
B. Low blood O₂
C. High blood CO₂
D. High blood pH

Answer: C

Explanation:

A. Incorrect: High O₂ reduces drive.
B. Incorrect: Low O₂ weaker than CO₂.
C. Correct: High CO₂ = strongest drive.
D. Incorrect: High pH decreases drive.

Q24. The term “dyspnoea” refers to:

A. Normal breathing
B. Rapid breathing
C. Difficulty in breathing
D. Stoppage of breathing

Answer: C

Explanation:

A. Incorrect: Normal = eupnoea.
B. Incorrect: Rapid = tachypnoea.
C. Correct: Dyspnoea = difficulty in breathing.
D. Incorrect: Apnoea = stoppage.

Q25. Which centre mainly regulates the basic rhythm of respiration?

A. Medullary respiratory centre
B. Apneustic centre
C. Pneumotaxic centre
D. Cerebral cortex

Answer: A

Explanation:

A. Correct: Medullary respiratory centre controls rhythm.
B. Incorrect: Apneustic modifies inspiration.
C. Incorrect: Pneumotaxic regulates rate.
D. Incorrect: Cortex allows voluntary control only.

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Part 7: Regulation of Respiration (25 MCQs)