Final answer:
Bronchoconstriction is the narrowing of bronchial tubes due to the constriction of smooth muscle around and within them, often associated with the condition of asthma. This constriction leads to difficulties in breathing and is regulated by the autonomic nervous system through parasympathetic-induced constriction and sympathetic-induced dilation.
Step-by-step explanation:
The Narrowing of Bronchial Tubes
The narrowing of bronchial tubes is known as bronchoconstriction. This occurs through the constriction of smooth muscle surrounding and within the bronchial walls. The bronchus is a tube connected to the trachea that branches into many subsidiaries, providing a passage for air to enter and leave the lungs. When the smooth muscle of the bronchi contracts, the size of the bronchioles decreases, which can restrict airflow and make breathing difficult.
Asthma is a common chronic disease where this phenomenon is typically observed. In asthmatic patients, bronchioles become inflamed, muscles around the bronchioles contract, mucus production is increased, and the chest feels tight, making breathing a struggle. The condition can be triggered by various factors, including allergies, temperature changes, exercise, or stress. The muscles in the bronchi are innervated by the parasympathetic and sympathetic nervous systems, which control muscle contraction and relaxation. Bronchoconstriction is influenced by the parasympathetic nervous system, while bronchodilation, or the increase in the size of the bronchiole, is promoted by the sympathetic nervous system.
Bronchitis is another health condition affecting the bronchi. During bronchitis, the walls of the bronchi become inflamed and congested with mucus, which narrows the airways and impedes the flow of air into the lungs. Both asthma and bronchitis illustrate the impact that changes in the bronchial tubes can have on respiratory health.