What is the primary trigger for the cough reflex?

What is the primary trigger for the cough reflex?

• A. Irritation of receptors in the nasopharynx
• B. Irritation of receptors in the conducting zone
• C. Irritation of receptors in the alveoli
• D. Irritation of receptors in the pleura

Answer: (B)

The cough reflex primarily arises from the irritation of receptors located in the conducting zone of the respiratory system. These receptors, which include mechanoreceptors and chemoreceptors, are sensitive to various stimuli such as foreign particles, irritants, and fluid. When these receptors are activated, they send signals via the vagus nerve to the brain, triggering the cough reflex as a means of expelling irritants and clearing the airway. The conducting zone, which consists of the trachea, bronchi, and bronchioles, plays a crucial role in this reflex. This zone is responsible for air conduction and houses the majority of the sensory receptors involved in initiating a cough. The reflex helps to protect the lungs from potential obstructions and infections, serving as a defensive mechanism. The other options represent different anatomical structures and areas where irritation can occur, but they do not primarily trigger the cough reflex. For instance, irritation of receptors in the nasopharynx can lead to sneezing rather than coughing; receptors in the alveoli are crucial for gas exchange and do not significantly contribute to cough initiation; irritation in the pleura may result in pleuritic pain but is not directly involved in the cough reflex itself.

The cough reflex primarily arises from the irritation of receptors located in the conducting zone of the respiratory system. These receptors, which include mechanoreceptors and chemoreceptors, are sensitive to various stimuli such as foreign particles, irritants, and fluid. When these receptors are activated, they send signals via the vagus nerve to the brain, triggering the cough reflex as a means of expelling irritants and clearing the airway.

The conducting zone, which consists of the trachea, bronchi, and bronchioles, plays a crucial role in this reflex. This zone is responsible for air conduction and houses the majority of the sensory receptors involved in initiating a cough. The reflex helps to protect the lungs from potential obstructions and infections, serving as a defensive mechanism.

The other options represent different anatomical structures and areas where irritation can occur, but they do not primarily trigger the cough reflex. For instance, irritation of receptors in the nasopharynx can lead to sneezing rather than coughing; receptors in the alveoli are crucial for gas exchange and do not significantly contribute to cough initiation; irritation in the pleura may result in pleuritic pain but is not directly involved in the cough reflex itself.