Bronchi


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Bronchi

 

branches of the windpipe in higher vertebrates (Amniota) and man. In the majority of animals the windpipe, or trachea, is divided into two main bronchi. Only in the Hatteria does a longitudinal fissure in the posterior section of the trachea mark the paired bronchi, which do not have separate cavities. In all other reptiles, and also in birds and mammals, the bronchi are well developed and extend inside the lungs. In reptiles, bronchi of the second order emerge from the main bronchi; these in turn divide into bronchi of the third and fourth orders, and so on; division of bronchi is especially complex in turtles and crocodiles. In birds, second-order bronchi are connected by parabronchi—canals along whose radii the so-called bronchioles branch off, branching and becoming a network of pneumatic capillaries. The bronchioles and the pneumatic capillaries of each parabronchus unite with the corresponding formations of the other parabronchi, thus forming a system of continuous air paths. The main bronchi, as well as certain side bronchi, widen at their ends into what are called air sacs. In mammals, from each main bronchus emerge secondary bronchi, which divide into ever smaller branches, forming the so-called bronchial tree. The very smallest of these branches become alveolar ducts, which end in alveoli. In mammals, besides the usual secondary bronchi, prearterial secondary bronchi are distinguished, which emerge from the main bronchi before the place where the pulmonary arteries cross them. Most often there is just one right prearterial bronchus, which in most Artiodactyla emerges directly from the trachea. The fibrous walls of the large bronchi contain cartilaginous half-rings joined in the rear by transverse bundles of smooth muscle. The mucous membrane of the bronchi is covered with ciliated epithelium. In the small bronchi the cartilaginous half-rings are replaced by individual nodules of cartilage. In the bronchioles there is no cartilage, and ring-like bundles of smooth muscle lie in a dense layer. In the majority of birds the first rings of the bronchi participate in the formation of the lower larynx.

In man the division of the trachea into the two main bronchi occurs at the level of the fourth and fifth thoracic vertebrae. Each bronchus then divides into ever smaller ones, ending in microscopically small bronchioles, which become the alveoli of the lungs. The walls of the bronchi are composed of smooth muscles and of hyaline cartilaginous rings that prevent the collapse of the bronchi; the bronchi are lined inside with mucous membrane. Along the branching paths of the bronchi are located numerous lymph nodes, which collect lymph from the lung tissues. The bronchi are supplied with blood by the bronchial arteries that emerge from the thoracic aorta; innervation is effected by branches of the vagus, sympathetic, and spinal nerves.

References in periodicals archive ?
(9,10,21) On the contrary, there are also studies indicating that there is no difference between the right and left bronchi in terms of aspiration rate.
We agreed he would ask the service provider to talk to me on phone after carrying out the examination.Korir called me the following day on behalf of Emanuel and confirmed he had seen gapeworms at the point of branching of the bronchi in one of the farmers' chickens.
In bronchiectasis, one or more of the bronchi are abnormally widened.
Furthermore, the bronchi of mammals formed bronchial tree, whereas in the ostrich, they formed an interconnected labyrinthine structure, which was consistent with F.
The mass is in the middle mediastinum, at the level of the carina and adjacent to the trachea extending to the subcarinal region, causing compression on the carina and both main bronchi, more pronounced on the left main bronchus.
After the macroscopic analysis, fragments of the trachea, tracheal bronchus, main and secondary bronchi, and lungs were removed from the parietal and mediastinal surfaces in their cranial, middle and caudal regions.
The signs of stable vascular alteration of the respiratory tract in case of bronchial remodeling are determined by their hypertrophy and angiogenesis manifested by 2-3 times increased number of vessels in the area of small and middle-size bronchi.[1],[2] Increased permeability of the vascular wall, stagnation phenomena, and increased general volume of the vascular bed are accompanied by bronchial obstruction, persisting inflammation, increased the temperature on the mucous surface with increased concentration of nitrogen monoxide in the exhaled breath.
Electronic bronchoscopy findings were mucosal hypertrophy, swelling, significant hyperemia, unevenness and luminal stenosis which were visible in the trachea, left and right main bronchi, right upper lobe and right intermediate bronchi, right lower lobe bronchus, as well as left upper and lower lobe bronchi, and total occlusion of right middle lobe bronchus (Figure 2).
The majority of the foreign bodies were localized to the two main bronchi, which was found to be consistent with the findings of Girardi et al.
It was within 2-6 [micro]m, and a particle size range deposited in the bronchi, in all dosage forms except the capsule preparation.
While most previous investigations have adopted the airway tree models with few bronchi due to difficulties in extraction from CT images and high computational complexity, few studies have been done for transient dynamics simulation of airflow in a CT-scanned human tracheobronchial tree with more than 100 outlets.
There were 2 (1.4%) deaths, both because of inability to retrieve FBs in time from main bronchus after being dislodged from right main bronchi leading to fall in oxygen saturation and subsequent cardiac arrest.