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Upper respiratory system, with the nasopharynx, oropharynx and laryngopharynx labeled at left. The upper portion of the pharynx, the nasopharynx, extends from the base of the skull to the upper surface of the soft palate. [2] It includes the space between the internal nares and the soft palate and lies above the oral cavity.
Details of upper respiratory tract. 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 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.
In the upper part of the respiratory tract, the nasal hair in the nostrils traps large particles, and the sneeze reflex may also be triggered to expel them. The nasal mucosa also traps particles preventing their entry further into the tract. In the rest of the respiratory tract, particles of different sizes become deposited along different ...
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]
The back surface is covered in a layer of column-shaped cells with cilia, similar to the rest of the respiratory tract. It also has mucus-secreting goblet cells. [2] There is an intermediate zone between these surfaces that contains cells that transition in shape. [4] The body of the epiglottis consists of elastic cartilage. [2]
In the first line of defense, inhaled bacteria are trapped by mucus and are swept toward the pharynx and are swallowed. [1] Bacteria which penetrate the mucous layer are dealt with a second line of defense which includes antimicrobial peptides that are secreted by the surface epithelium of the respiratory tract which kill many strains of ...
The anatomy of a typical mammalian respiratory system, below the structures normally listed among the "upper airways" (the nasal cavities, the pharynx, and larynx), is often described as a respiratory tree or tracheobronchial tree (figure on the left). Larger airways give rise to branches that are slightly narrower, but more numerous than the ...