The bronchial reflex is a protective mechanism of the respiratory system. It occurs when irritants, such as smoke or allergens, stimulate sensory nerves in the airways. This triggers a response that leads to bronchoconstriction, narrowing the air passages to limit the entry of harmful substances. Additionally, the bronchial reflex can cause coughing or increased mucus production. These actions help clear the airways and protect the lungs from potential damage. This reflex is an essential part of the body's defense against respiratory irritants and is closely linked to the functioning of the nervous system and respiratory system.