What type of receptors are located in the carina?

• A. Cough receptors
• B. Stretch receptors
• C. Pain receptors
• D. Thermoreceptors

Answer: (A)

The carina, which is the ridge at the base of the trachea where it bifurcates into the left and right main bronchi, is equipped with specialized receptors known as cough receptors. These receptors play an essential role in the respiratory system by detecting the presence of irritants or excessive mucus in the airways. When activated, they trigger the cough reflex, helping to clear the air passages to maintain proper ventilation and protect the lower airways from potential pathogens or debris.

In contrast, stretch receptors are primarily found in the lungs and play a role in regulating the depth of breathing based on lung expansion. Pain receptors are typically associated with detecting injury or noxious stimuli in various tissues but are not specifically located in the carina for respiratory function. Thermoreceptors, which sense changes in temperature, are also not a primary feature of the carina's functionality related to the cough reflex. Thus, the presence of cough receptors at the carina is specifically geared towards facilitating respiratory hygiene and reflexive mechanisms necessary for maintaining clear airways.