The respiratory system starts at the nose and mouth, with the trachea carrying air to the lungs through the bronchi and bronchioles. The diaphragm is the main muscle used in breathing, and asthma, bronchospasm, and bronchitis are common respiratory conditions.
A bronchus is one of the large tubes that lead from the human windpipe to the lungs. There is one large bronchus in each lung that branches into smaller bronchi within the lungs. The bronchi carry air in and out of the lungs.
The respiratory system begins at the nose and mouth, which meet at the pharynx. At the bottom of the pharynx are the esophagus, for food, and the trachea, for air. The epiglottis is a flap of tissue that covers the trachea during swallowing, to prevent food from passing into the airways as it enters the esophagus.
At the top of the trachea is the larynx. This is the home of the vocal cords, which vibrate to create words and sounds. The trachea continues past the neck and into the chest cavity, where it divides into the bronchi. The bronchi extend into the lungs.
The right main bronchus is larger than the left. It divides into three lobar bronchi. The left main bronchus divides into two lobar bronchi. The lobar bronchi then branch into what are called tertiary bronchi and then into smaller bronchioles.
The bronchioles eventually branch into alveolar ducts and sacs. The alveoli, or air sacs, are the primary units for exchanging oxygen and carbon dioxide in the lungs. A human being has about 480 million alveoli.
The muscle that separates the chest from the abdomen is the diaphragm. This is the main muscle used in breathing. Inhalation occurs when the diaphragm contracts and moves downward. The air pressure within the chest cavity is reduced, causing air to flow into the lungs. During exhalation, the diaphragm is relaxed and pushes the air out of the chest.
Asthma is a disease in which the airways are blocked, often causing wheezing and difficult or painful breathing. Treatment may include inhaled corticosteroids to reduce inflammation and bronchodilators to keep the airways open. There is no cure for asthma and treatment is based on symptom control.
Bronchospasm is the contraction of smooth muscle in a bronchus or bronchiole. This condition can be caused by irritation or damage to the lining of the airways, by infection or by an allergy. Symptoms include severe cough and wheezing. Treatment is similar to that for asthma.
Bronchitis is inflammation of the bronchial airways related to infection, allergies, or other causes. When the lining of the bronchial tubes becomes inflamed, they swell and create excessive secretions. Antibiotics, cold mist vaporizers, and liquids can be included in your treatment.
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