In the mediastinum , at the level of the fifth thoracic vertebra, the trachea divides into the right and left primary bronchi. The bronchi branch into smaller and smaller passageways until they terminate in tiny air sacs called alveoli. The cartilage and mucous membrane of the primary bronchi are similar to that in the trachea.
As the branching continues through the bronchial tree , the amount of hyaline cartilage in the walls decreases until it is absent in the smallest bronchioles. As the cartilage decreases, the amount of smooth muscle increases. The mucous membrane also undergoes a transition from ciliated pseudostratified columnar epithelium to simple cuboidal epithelium to simple squamous epithelium. Got it wrong! Frances Brook Wilson. Jan 12, AM.
Ilias Tsiabardas. Jan 7, PM. David Wilkes. Hey genius! Time to save your score! Sign up and get 50 welcome coins 7, players are online. Create an account to leave a comment. Your Choice Regarding Cookies on this Site. These cookies allow us to analyze site usage so we can measure and improve performance. The right bronchus is slightly larger than the left one. Because of this, foreign objects breathed into the lungs often end up in the right bronchus.
The bronchi are lined with the same type of mucus that lines the rest of the respiratory tract. Deeper into the lungs, each bronchus is further divided into five smaller, secondary bronchi, which provide air to the lobes of the lungs. The secondary bronchi continue to branch off to form the tertiary bronchi, which are further divided into terminal bronchioles. There are as many as 30, tiny bronchioles in each lung. They lead to the alveoli by way of alveolar ducts.
Together, the trachea and the two primary bronchi are referred to as the bronchial tree. At the end of the bronchial tree lie the alveolar ducts, the alveolar sacs, and the alveoli. The tubes that make up the bronchial tree perform the same function as the trachea: they distribute air to the lungs. The alveoli are responsible for the primary function of the lungs, which is exchanging carbon dioxide and oxygen.
COPD is a serious disease that can lead to lung cancer and is often fatal. Asthma is an illness characterized by constriction of the bronchi bronchospasm , which in turn interferes with the passage of air from the environment to the alveoli of the lungs.
Attacks of asthma are often triggered by allergies, exercise, or irritants. When the walls of the bronchi become irreversibly scarred, they can thicken, causing mucus to build up and become a breeding ground for bacteria. Over time, there is a decrease in lung function. Bronchiectasis is usually associated with other illnesses, such as COPD, cystic fibrosis, and recurrent cases of pneumonia. Bronchiolitis is caused by a viral infection, most commonly respiratory syncytial virus RSV.
The bronchioles swell and fill with mucus, making breathing difficult. Infants under three months old are the most likely to be affected by this disease.
A rare and serious type of bronchiolitis, called bronchiolitis obliterans also known as "popcorn lung" , is a chronic form of the illness that mainly affects adults. Bronchopulmonary dysplasia BPD can occur in newborns usually those who are premature who are being treated with oxygen or are on a ventilator for another breathing problem.
The high amounts of oxygen and pressure used in these therapies can overstretch the alveoli, inflaming and damaging the inside lining of the airways. A bronchospasm occurs when your airways constrict, or narrow, causing wheezing and difficulty breathing. Bronchospasms are a symptom of many conditions that affect the airways, including asthma, seasonal allergies, and COPD.
Bronchogenic carcinoma is an older term for cancers that arise in the bronchi and bronchioles. Now this term is used interchangeably with lung cancer of all types. This is the type of lung cancer more commonly found in non-smokers, women, and young adults. These lung cancers tend to be aggressive and may not be found until they have already metastasized spread to other parts of the body.
A bronchopleural fistula is an abnormal passageway a sinus tract that develops between the bronchi and the space between the membranes that line the lungs the pleural cavity. It is a serious complication often caused by lung cancer surgery, but may also develop after chemotherapy, radiation, or an infection.
The following common imaging tests are used to diagnose problems that involve the bronchi. A chest X-ray is often the first procedure used to visualize the lungs. X-rays are useful for identifying causes of aspiration, pneumonia, and lung tumors. During a bronchoscopy , a tube called a bronchoscope is inserted through the mouth and into the bronchi.
A bronchoscopy may be performed in order to evaluate symptoms such as a persistent cough or coughing up blood, but can also be used to treat some conditions, such as bleeding in the airways, or removal of a foreign body. An endobronchial ultrasound can look at tissues that are deeper in the lungs past the bronchial walls. When a tumor is located, a needle biopsy may be performed under the guidance of the endobronchial ultrasound, making it possible to obtain tissue from a tumor without the need for an open lung biopsy.
Because there are so many different types of conditions and diseases that can affect the bronchi, treatments vary widely, ranging from medications to surgery. These medications help relax the muscles around the air passages, which makes breathing easier by widening the airway openings.
They are a mainstay of asthma treatment, and usually administered via a nebulizer or an inhaler with a spacer. They help reduce swelling in the airways and decrease the amount of mucus that is produced.
Like bronchodilators, they can be given via a nebulizer or an inhaler with a spacer. Bronchitis often goes away on its own or can be treated with over-the-counter medications, called expectorants, that loosen mucus. Antibiotics are usually prescribed when a bacterial infection affects the bronchial passages.
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