NCERT Class 11 Science — Chapter 4: Breathing and Exchange of Gases

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Peripheral receptors associated with which blood vessels can detect changes in CO2 and H+ for respiratory control?

Official previous-year question

Verified 1 Aug 2026.

Options

ARenal artery and portal vein
BAortic arch and carotid artery
CPulmonary veins and venae cavae
DFemoral artery and iliac artery

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Solution

Correct Option

The correct option is Aortic arch and carotid artery.

Explanation

Respiratory rhythm is regulated by neural and chemical mechanisms to maintain homeostasis. Chemical regulation is primarily mediated by chemoreceptors, which detect changes in the concentration of carbon dioxide ($CO_2$), hydrogen ions ($H^+$), and oxygen ($O_2$) in the body fluids.

Detailed Analysis

Peripheral Chemoreceptors: These are specialized sensory structures located in the aortic arch (known as aortic bodies) and the carotid arteries (known as carotid bodies).
Sensitivity: These receptors are highly sensitive to increases in $CO_2$ concentration and hydrogen ions ($H^+$). They also respond to a significant fall in partial pressure of oxygen ($pO_2$), though their primary trigger under normal conditions is $CO_2$ and pH levels.
Mechanism: When these receptors detect excess $CO_2$ or $H^+$, they send neural signals to the respiratory rhythm center in the medulla oblongata. The aortic bodies transmit signals via the vagus nerve, while the carotid bodies transmit via the glossopharyngeal nerve. This stimulation results in an increased rate and depth of breathing to eliminate excess $CO_2$ and reduce acidity.
Incorrect Options: The pulmonary veins, venae cavae, renal arteries, portal veins, femoral arteries, and iliac arteries do not contain the specific chemoreceptors responsible for regulating respiratory rhythm.

Key Takeaway: Peripheral chemoreceptors associated with the aortic arch and carotid artery recognize changes in $CO_2$ and $H^+$ concentration and signal the respiratory rhythm center to adjust breathing.

Your note

More from Chapter 4: Breathing and Exchange of Gases

Consider the following statements about the larynx and epiglottis in humans: 1. Larynx is a cartilaginous box associated with sound production. 2. Epiglottis facilitates the entry of food into the larynx. 3. Epiglottis is a fibrous flap devoid of elasticity. Which of the statements given above is/are correct?

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Consider the following about diffusion of gases in the lungs: 1. It is driven mainly by partial pressure gradients. 2. Solubility of gases has no effect on the rate. 3. Membrane thickness influences the rate of diffusion. Which of the statements given above is/are correct?

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Which of the following pathways accounts for the majority of carbon dioxide transport in blood?

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Which enzyme predominantly present in RBCs catalyses the reversible formation of bicarbonate from carbon dioxide and water?

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With reference to gas exchange mechanisms among animals, consider the following statements: 1. Insects rely on gills for respiration. 2. Most aquatic arthropods depend on vascularised bags for respiration. 3. Most aquatic arthropods depend on gills for respiration. Which of the statements given above are correct?

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Correct Option

The correct option is Aortic arch and carotid artery.

Explanation

Detailed Analysis

Peripheral Chemoreceptors: These are specialized sensory structures located in the aortic arch (known as aortic bodies) and the carotid arteries (known as carotid bodies).
Sensitivity: These receptors are highly sensitive to increases in $CO_2$ concentration and hydrogen ions ($H^+$). They also respond to a significant fall in partial pressure of oxygen ($pO_2$), though their primary trigger under normal conditions is $CO_2$ and pH levels.
Mechanism: When these receptors detect excess $CO_2$ or $H^+$, they send neural signals to the respiratory rhythm center in the medulla oblongata. The aortic bodies transmit signals via the vagus nerve, while the carotid bodies transmit via the glossopharyngeal nerve. This stimulation results in an increased rate and depth of breathing to eliminate excess $CO_2$ and reduce acidity.
Incorrect Options: The pulmonary veins, venae cavae, renal arteries, portal veins, femoral arteries, and iliac arteries do not contain the specific chemoreceptors responsible for regulating respiratory rhythm.