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The upper respiratory tract can refer to the parts of the respiratory system lying above the vocal folds, or above the cricoid cartilage. [4] [5] The larynx is sometimes included in both the upper and lower airways. [6] The larynx is also called the voice box and has the associated cartilage that produces sound.
The trachea begins at the lower edge of the cricoid cartilage of the larynx [3] at the level of sixth cervical vertebra (C6) [2] and ends at the carina, the point where the trachea branches into left and right main bronchi., [2] at the level of the fourth thoracic vertebra (T4), [2] although its position may change with breathing. [3]
The tract is divided into an upper and a lower respiratory tract. The upper tract includes the nose, nasal cavities, sinuses, pharynx and the part of the larynx above the vocal folds. The lower tract (Fig. 2.) includes the lower part of the larynx, the trachea, bronchi, bronchioles and the alveoli.
The lower respiratory tract consists of the trachea (windpipe), bronchial tubes, bronchioles, and the lungs. [6] Lower respiratory tract infections (LRIs) are generally more severe than upper respiratory infections. LRIs are the leading cause of death among all infectious diseases. [7] The two most common LRIs are bronchitis and pneumonia. [8]
Airway tone is a key determinant of lung function and the presence of respiratory symptoms in obstructive lung diseases such as asthma, where baseline airway tone is elevated. [2] The upper extreme of the spectrum of airway tone represents bronchoconstriction, wherein the airway smooth muscles are significantly contracted, while the lower ...
Upper and lower airway. Airway obstruction is a blockage of respiration in the airway that hinders the free flow of air. Airway obstructions can occur either in the upper airway or lower airway. The upper airway consists of the nose, throat, and larynx. The lower airway comprises the trachea, bronchi, and bronchioles. [1] [page needed]
A bronchus (/ ˈ b r ɒ ŋ k ə s / BRONG-kəs; pl.: bronchi, / ˈ b r ɒ ŋ k aɪ / BRONG-ky) is a passage or airway in the lower respiratory tract that conducts air into the lungs.The first or primary bronchi to branch from the trachea at the carina are the right main bronchus and the left main bronchus.
The lower, oblique fissure, separates the lower from the middle and upper lobes and is closely aligned with the oblique fissure in the left lung. [1] [7] The mediastinal surface of the right lung is indented by a number of nearby structures. The heart sits in an impression called the cardiac impression.