respiratory system

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respiratory system:

see respirationrespiration,
process by which an organism exchanges gases with its environment. The term now refers to the overall process by which oxygen is abstracted from air and is transported to the cells for the oxidation of organic molecules while carbon dioxide (CO2
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Respiratory system

The system of organs involved in the acquisition of oxygen and the elimination of carbon dioxide by an organism. The lungs and gills are the two most important structures of vertebrates involved in the phase known as external respiration, or gaseous exchanges, between the blood and environment. Internal respiration refers to the gaseous exchanges which occur between the blood and cells. Certain other structures in some species of vertebrates serve as respiratory organs; among these are the integument or skin of fishes and amphibians. The moist, highly vascular skin of anuran amphibians is important in respiration. Certain species of fish have a vascular rectum which is utilized as a respiratory structure, water being taken in and ejected regularly by the animal. Saclike cloacal structures occur in some aquatic species of turtles. These are vascular and are intermittently filled with, and emptied of, water. It is thought that they may function in respiration. During embryonic life the yolk sac and allantois are important respiratory organs in certain vertebrates. See Yolk sac

Structurally, respiratory organs usually present a vascular surface that is sufficiently extensive to provide an adequate area of absorption for gaseous exchange. This surface is moist and thin enough to allow for the passage of gases.

The shape and volume of the lung, because of its pliability, conforms almost completely to that of its cavity. The lungs are conical; each has an apex and a base, two surfaces, two borders, and a hilum. The apex extends into the superior limit of the thoracic cavity. The base is the diaphragmatic surface. The costal surface may show bulgings into the intercostal spaces. The medial surface has a part lying in the space beside the vertebral column and a part imprinted by the form of structures bulging outward beneath the mediastinal pleura. The cardiac impression is deeper on the left lung because of the position of the heart.

For convenience the lung may be divided into anatomical areas. The bronchial tree branches mainly by dichotomy. The ultimate generations, that is, the respiratory bronchioles, alveolar ducts, and alveoli constitute all of the respiratory portion of the lung. The trachea and extrapulmonary bronchi are kept open by C-shaped bars of hyaline cartilage. When in their branching the bronchi and bronchioles are reduced to a diameter of 1 mm or less, they are then free of cartilage and are called terminal bronchioles. One of the terminal bronchioles enters the apex of a secondary lobule of the lung. These secondary lobules are anatomic units of the lung, whose hexagonal bases rest on the pleura or next to a bronchiole or blood vessel. Finer lines divide the bases of the secondary lobules into smaller areas. These are the bases of primary lobules, each served by a respiratory bronchiole. See Lung, Respiration

The blood supply to the lung is provided by the pulmonary and the bronchial arteries. The nerves which supply the lung are branches of the vagus and of the thoracic sympathetic ganglia 2, 3, and 4. Efferent vagal fibers are bronchoconstrictor and secretory, whereas the afferents are part of the arc for the breathing reflex. Efferent sympathetic fibers are bronchodilators; hence, the use of adrenalin for relief of bronchial spasm resulting from asthma. See Nervous system (vertebrate)

respiratory system

[′res·prə‚tȯr·ē ¦sis·təm]
The structures and passages involved with the intake, expulsion, and exchange of oxygen and carbon dioxide in the vertebrate body.
References in periodicals archive ?
In this study, we aimed to determine risk factors for lower respiratory tract infections in terms of low socioeconomic level in our region.
Cases were taken in children between 6 months to 6 years of age presenting with Gastroenteritis and Lower respiratory tract infection and controls were taken in the same age group with minor ailments after fulfilling the inclusion and exclusion criteria were included in the study.
Respiratory syncytial virus (RSV) "is the most common viral cause of lower respiratory tract infections in infants and, consistent with our findings, RSV bronchiolitis was reported to be the leading primary diagnosis for hospital discharges among infants in previous years," the researchers reported.
When the two cohorts of children with Down syndrome were combined, 180 children (46%) had a risk factor for severe lower respiratory tract infections caused by respiratory syncytial virus (RSV).
One would expect that inhaled hygroscopic particles would be retained in the lower respiratory tract with greater efficiency, and this hypothesis has been confirmed experimentally (11,12).
Of infections in the SLE patients, 29% involved the skin and/or mucosa, 22% involved the lower respiratory tract, and 14% involved the upper respiratory tract, Dr.
Among patients with lower respiratory tract infections, the most commonly used class was the macrolides, in 43%, followed by the fluoroquinolones, in about 29%.
To date, the literature contains only a few scattered case reports and a few cases mentioned in reviews of amyloidosis localized to either the upper or lower respiratory tract.
Virazole is indicated for the treatment of hospitalized infants and young children with severe lower respiratory tract infections due to respiratory syncytial virus (RSV).
Other more deadly infections, such as the H5N1 bird flu, infect the lower respiratory tract deep in the lung where they can cause deadly pneumonia.
Down syndrome by itself is a risk factor for severe respiratory syncytial virus infections of the lower respiratory tract and may merit an indication for prophylaxis with palivizumab, according to investigators who followed 395 patients in the Netherlands.

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