Bronchi
The bronchi are key structures in the respiratory system, serving as the main air passageways that branch off from the trachea and lead into the lungs. They consist of rings of cartilage and muscle fibers, which provide rigidity and prevent collapse, ensuring efficient air transport. The right bronchus is shorter, wider, and more vertically oriented than the left, reflecting important anatomical differences. Once inside the lungs, the bronchi divide into smaller bronchi and eventually into bronchioles, facilitating the exchange of oxygen and carbon dioxide.
However, the bronchi can be affected by various disorders, the most prevalent being bronchitis, which can be acute or chronic. Acute bronchitis typically follows infections and shows symptoms like cough and congestion, while chronic bronchitis is often associated with long-term smoking and results in a persistent productive cough. Conditions like asthma also involve bronchi inflammation, leading to breathing difficulties. Understanding the structure and function of the bronchi is vital for recognizing the implications of respiratory diseases and the importance of maintaining lung health.
Subject Terms
Bronchi
Anatomy or system affected: Lungs, respiratory system
Definition: The large, rigid breathing tubes that connect the trachea to the inside of the lungs
Structure and Functions
The bronchi are a direct continuation of the trachea, which separates into the right and left mainstem bronchi at the level of the fifth thoracicvertebra of the spinal column. They are composed of rings of cartilage supported by thick muscle fibers with a mucous membrane interior coating. This structure renders the bronchi rigid and not easily collapsible. The left bronchus is about five centimeters in length and enters the lung at the level of the sixth thoracic vertebra. The right bronchus is shorter, measuring about two and a half centimeters in length, and enters the lung at the level of the fifth thoracic vertebra. The right bronchus also differs in that it is wider and runs at a more vertical angle than its left counterpart. The bronchi join with the lung, becoming the lobar bronchi, and further branch into subsequently smaller bronchi, eventually being called the bronchioles.
The bronchi serve primarily to transport air between the trachea and the lungs. They bring freshly oxygenated air into the lungs from the outside environment and transport old, carbon dioxide–filled air out of the lungs.
Disorders and Diseases
The bronchi are susceptible to a variety of diseases and dysfunctions, the most common being bronchitis. Bronchitis is an inflammation of the bronchi and can be secondary to various mechanisms. Acute bronchitis is usually infectious and is most common during the winter season. The symptoms are nonspecific and can include fever, cough, nasal congestion, and wheezing. Acute bronchitis can be caused by viruses such as influenza and bacteria such as Mycoplasma pneumoniae and Chlamydia pneumoniae. It can also be caused by various noninfectious outdoor or household irritants. Treatment consists of antibiotics for bacterial causes, bronchodilator inhalers, over-the-counter fever reducers and cough suppressants, fluids, and rest. Chronic bronchitis is a separate disorder of inflammation of the bronchi that is common in smokers. A cough productive of sputum for three months and occurring for at least two years in a row is required for a formal diagnosis. Symptoms are similar to those of acute bronchitis. There is no cure for chronic bronchitis, but treatment aimed at symptom control often involves bronchodilator inhalers, steroids, and smoking cessation.
Asthma involves chronic inflammation of the lungs with consequent narrowing of the bronchi and airway obstruction, leading to episodes of coughing, wheezing, and difficulty breathing. Treatment involves bronchodilators such as albuterol, steroids, and leukotriene modifiers. In the twenty-first century, researchers began exploring alternative treatments for asthma for adults and children that altered RNA proteins.
Additionally, the precipitous downward angle of the right mainstem bronchus lends itself to foreign body impaction, especially in children. It also makes it easier for liquids to enter the right lung, causing aspiration pneumonia.
Bibliography
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