Bronchioles what do they do

The density of cilia decreases as the bronchioles branch off and get smaller and smaller. The bronchioles are lined with club cells that secrete surfactants—compounds that reduce surface tension within airways, allowing them to expand during inhalation and preventing them from collapsing during exhalation. Club cells also secrete enzymes that break down debris and irritants so that they can be readily excreted from the lung.

The function of the bronchioles is to deliver air to a diffuse network of around million alveoli in the lungs. Carbon dioxide collected by the alveoli is then expelled from the lungs as you exhale. The bronchioles are not inert. The smooth muscles that surround the airways will automatically constrict close and dilate open to control the flow of air in and out of the lungs.

Dilation of the airways bronchodilation occurs when the lungs need more oxygen, such as during exercise or at higher altitudes. By contrast, narrowing of the airways, bronchoconstriction , can occur when irritants or allergens are inhaled. While this is meant to keep foreign substances from entering the lungs, it can restrict breathing, sometimes severely. Certain medications, inflammation, and disease can do the same.

Symptoms of bronchoconstriction include:. Bronchoconstriction may be accompanied by bronchiolar obstruction caused when the airways are blocked, as from the overproduction of mucus. Symptoms of bronchiolar obstruction can overlap with those of bronchoconstriction and include:. The following conditions involve the bronchioles:. Asthma is an allergic condition triggered primarily by allergens or irritants in the air and, in children, respiratory infections. Bronchiolitis is inflammation of the bronchioles.

It's most common in babies between 3 months and 6 months of age who become infected with a virus such as respiratory syncytial virus RSV or influenza.

Bronchiolitis obliterans is a rare inflammatory condition that causes scarring fibrosis of the bronchioles to the extent that the airways are blocked.

Bronchiolitis obliterans is irreversible: In severe cases a lung transplant may be needed. Cystic fibrosis is an inherited, life-threatening disorder that damages the lungs and digestive system.

Cystic fibrosis causes goblet cells to produce excessive amounts of mucus that clogs tubes, ducts, and passages in the respiratory and gastrointestinal tracts. As the disease advances, it can cause scarring of the bronchioles as well as the collapse of the lung atelectasis. There is no cure for cystic fibrosis, but it can be slowed with medications, antibiotics, physical therapies, and preventive vaccinations. Emphysema is one manifestation of congestive obstructive pulmonary disease COPD , a group of lung diseases that block airflow and make it difficult to breathe.

In emphysema, damage to the alveoli and lung tissue causes the bronchioles to collapse. The leading cause of emphysema is smoking. Others include air pollution, secondhand smoke, chronic respiratory infections, and occupational exposure to dust and chemicals. Emphysema can't be reversed but it can be treated with bronchodilators, anti-inflammatory drugs, supplemental oxygen, and surgery to remove damaged tissue.

Some treatments are designed to alleviate acute episodic symptoms called exacerbations , while others prevent the worsening or recurrence of symptoms. Acute conditions, like bronchiolitis, may only need short-term treatment to resolve the underlying infection.

Chronic bronchiolar obstruction, such as occurs with COPD and cystic fibrosis, typically require medications, physical therapies, and supportive care to slow disease progression.

Surgery sometimes is needed. In addition, many people with chronic obstructive disorders like COPD and cystic fibrosis may find 20 to 30 minutes of physical exercise five days per week is a useful part of treatment.

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Chaudhry R, Bordoni B. Anatomy, thorax, lungs. The cells in our bodies need oxygen to stay alive. Carbon dioxide is made in our bodies as cells do their jobs. The lungs and respiratory system allow oxygen in the air to be taken into the body, while also letting the body get rid of carbon dioxide in the air breathed out.

When you breathe in, the diaphragm moves downward toward the abdomen, and the rib muscles pull the ribs upward and outward. This makes the chest cavity bigger and pulls air through the nose or mouth into the lungs. In exhalation, the diaphragm moves upward and the chest wall muscles relax, causing the chest cavity to get smaller and push air out of respiratory system through the nose or mouth.

Every few seconds, with each inhalation, air fills a large portion of the millions of alveoli. In a process called diffusion, oxygen moves from the alveoli to the blood through the capillaries tiny blood vessels lining the alveolar walls.

Once in the bloodstream, oxygen gets picked up by the hemoglobin in red blood cells. This oxygen-rich blood then flows back to the heart, which pumps it through the arteries to oxygen-hungry tissues throughout the body. In the tiny capillaries of the body tissues, oxygen is freed from the hemoglobin and moves into the cells. Carbon dioxide, made by the cells as they do their work, moves out of the cells into the capillaries, where most of it dissolves in the plasma of the blood.

Blood rich in carbon dioxide then returns to the heart via the veins. From the heart, this blood is pumped to the lungs, where carbon dioxide passes into the alveoli to be exhaled. Primary bronchi are located in the upper portion of the lungs, with secondary bronchi near the center of the lungs. Tertiary bronchi are located near the bottom of these organs, just above the bronchioles. No gas exchanges occur in any of the bronchi. When the bronchi become swollen due to irritants or infection, bronchitis results and makes breathing more difficult.

Bronchitis sufferers also tend to have much more mucus and phlegm than someone without inflamed bronchi. The trachea, or windpipe, helps supply air to the lungs by providing a passage way from the mouth.

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