WordNet

relating to or associated with the bronchi; "bronchial tubes"; "bronchial pneumonia"

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気管支の
bronchusの複数形

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/03/02 15:05:41」(JST)

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A bronchus (plural bronchi, adjective bronchial) is a passage of airway in the respiratory tract that conducts air into the lungs. The bronchus branches into smaller tubes, which in turn become bronchioles.^[1] No gas exchange takes place in this part of the lungs.

The human trachea (windpipe) divides into two main bronchi (also mainstem bronchi), the left and the right, at the level of the sternal angle and of the fifth thoracic vertebra or up to two vertebrae higher or lower, depending on breathing, at the anatomical point known as the carina. The right main bronchus is wider, shorter, and more vertical than the left main bronchus.^[2] The right main bronchus subdivides into three lobar bronchi, while the left main bronchus divides into two. The lobar bronchi divide into tertiary bronchi, also known as segmentalinic bronchi, each of which supplies a bronchopulmonary segment. A bronchopulmonary segment is a division of a lung separated from the rest of the lung by a connective tissue septum. This property allows a bronchopulmonary segment to be surgically removed without affecting other segments. There are ten segments per lung, but due to anatomic development, several segmental bronchi in the left lung fuse, giving rise to eight. The segmental bronchi divide into many primary bronchioles which divide into terminal bronchioles, each of which then gives rise to several respiratory bronchioles, which go on to divide into two to 11 alveolar ducts. There are five or six alveolar sacs associated with each alveolar duct. The alveolus is the basic anatomical unit of gas exchange in the lung.

The hyaline cartilage forms an incomplete ring in the bronchi, giving them a "D"-shaped appearance in the larger bronchi (as compared with the "O"-shaped complete cartilaginous rings of the trachea), and as small plates and islands in the smaller bronchi. Smooth muscle is present continuously around the bronchi.

In the mediastinum, at the level of the fourth thoracic vertebra, the trachea divides into the right and left primary bronchi. The bronchi branch into smaller and smaller passageways until they terminate in tiny air sacs called alveoli.

The cartilage and mucous membrane of the primary bronchi are similar to those in the trachea. As the branching continues through the bronchial tree, the amount of hyaline cartilage in the walls decreases until it is absent in the smallest bronchioles. As the cartilage decreases, the amount of smooth muscle increases. The mucous membrane also undergoes a transition from ciliated pseudostratified columnar epithelium to simple cuboidal epithelium to simple squamous epithelium.

The alveolar ducts and alveoli consist primarily of simple squamous epithelium, which permits rapid diffusion of oxygen and carbon dioxide. Exchange of gases between the air in the lungs and the blood in the capillaries occurs across the walls of the alveolar ducts and alveoli.

Role in disease

Bronchitis is defined as inflammation of the bronchi. There are two main types: acute and chronic. Acute bronchitis is usually caused by viral or bacterial infections. Chronic bronchitis is a form of COPD, usually associated with smoking or long-term exposure to irritants. Asthma is hyperreactivity of the bronchi with an inflammatory component, often in response to allergens.

While the left mainstem bronchus departs from the trachea at an angle, the right mainstem bronchus is almost a vertical continuation of the trachea. This anatomy predisposes the right lung to several problems:

If food, liquids, or foreign bodies are aspirated, they often will lodge in the right mainstem bronchus. Aspiration pneumonia may result.
If the endotracheal tube used for intubation is inserted too far, it usually lodges in the right mainstem bronchus. This allows ventilation of the right lung, but leaves the left lung useless.

Additional images

cross sectional cut of a human secondary bronchus

Transverse section of thorax, showing relations of pulmonary artery
Mainstem bronchi seen branching off the trachea (labeled at top), with the left mainstem bronchi passing below the aortic arch before branching into smaller bronchi.

References

^ Maton, Anthea; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall. ISBN 0-13-981176-1.^{[page needed]}
^ Brodsky, JB; Lemmens, JM (2003). "Left Double-Lumen Tubes: Clinical Experience With 1,170 Patients". Journal of Cardiothoracic and Vascular Anesthesia 17 (3): 289–98. doi:10.1016/S1053-0770(03)00046-6. PMID 12827573. http://ether.stanford.edu/library/thoracic_anesthesia/One-Lung%20Ventilation/DLT%20Placement.pdf.

Moore, Keith L. and Arthur F. Dalley. Clinically Oriented Anatomy, 4th ed. (1999). ISBN 0-7817-5936-6

UpToDate Contents

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English Journal

Development of an in vitro model of human bronchial epithelial barrier to study nanoparticle translocation.

George I1, Vranic S2, Boland S3, Courtois A4, Baeza-Squiban A5.
Toxicology in vitro : an international journal published in association with BIBRA.Toxicol In Vitro.2015 Feb;29(1):51-8. doi: 10.1016/j.tiv.2014.08.003. Epub 2014 Sep 6.
Inhalation is the most frequent route of unintentional exposure to nanoparticles (NPs). Our aim was to compare different in vitro models of human lung epithelial monolayers for their suitability to assess the translocation of 50nm fluorescently labelled silica NPs (50nm-SiO2-FITC-NPs). Human bronchi
PMID 25197033

Endurance training and the risk of bronchial asthma in female cross-country skiers.

Zebrowska A1, Głuchowska B, Jastrzębski D, Kochańska-Dziurowicz A, Stanjek-Cichoracka A, Pokora I.
Advances in experimental medicine and biology.Adv Exp Med Biol.2015;840:29-34. doi: 10.1007/5584_2014_21.
Exercise is one of the crucial factors responsible for asthma development and exacerbation. The purpose of the present study was to assess the risk of bronchial asthma in female athletes. Spirometric evaluations and physical exercise test were performed and exhaled nitric oxide (eNO) levels were mea
PMID 25310943

Impulse oscillometry in the diagnosis of airway resistance in chronic obstructive pulmonary disease.

Piorunek T1, Kostrzewska M, Cofta S, Batura-Gabryel H, Andrzejczak P, Bogdański P, Wysocka E.
Advances in experimental medicine and biology.Adv Exp Med Biol.2015;838:47-52. doi: 10.1007/5584_2014_49.
Spirometry is a standard lung function test for diagnosis and staging of chronic obstructive pulmonary disease (COPD). Impulse oscillometry (IOS) can be complementary to spirometry, especially in patients at advanced age and with physical or mental disorders who cannot be diagnosed through spirometr
PMID 25256340

Japanese Journal

気管支喘息治療におけるフルチカゾンプロピオン酸エステル/ホルモテロールフマル酸塩水和物エアゾールの有用性の検討 : 吸入補助器具(スペーサー)による影響

保澤総一郎,田中裕士,森富美子 [他]
アレルギー・免疫 22(8), 1106-1118, 2015-08
NAID 40020539072

臨床研究・症例報告模擬症例を用いた小児気管支喘息管理についての調査結果

清益功浩,南部光彦,岡本和美 [他]
小児科臨床 68(8), 1507-1512, 2015-08
NAID 40020527814

Long-term survival for advanced esophageal cancer patients with an esophago-bronchial fistula can be achieved by timely multimodality therapy

Yoshida Takahiro,Tangoku Akira,Furukita Yoshihito [他]
Esophagus : official journal of the Japan Esophageal Society 12(3), 277-285, 2015-07
NAID 40020539692

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拡張検索	「bronchial tube」「intrabronchial」

「bronchial tube」

Bronchus (pleural Bronchi)
	Conducting passages.
	Front view of cartilages of larynx, trachea and bronchi.
Latin	Bronchus (plural bronchi)
Gray's	subject #237 1084
System	Respiratory system
Artery	Bronchial artery
Vein	Bronchial vein
Nerve	Pulmonary branches of vagus nerve
MeSH	Bronchi