What Is the Bronchial Tree?

The bronchial branches that directly send spontaneous bronchial tubes emit many smaller bronchial tubes during their travel. These small bronchial tubes continue to branch into many smaller bronchial tubes. As a result, the entire tree constituted a very complicated inverted tree similar to the branch system, hence the name bronchial tree. The bronchial tubes at all levels on the bronchial tree have both a common general structure and their own structural characteristics. As the diameter of the bronchi becomes thinner and thicker, the structure of the tube wall has a certain regularity.

Chinese name: Bronchial tree
Foreign name: bronchial tree

Make up: Ciliated cells, goblet cells, basal cells
Owning system: Respiratory system
Features: Gas exchange and discharge of tiny foreign matter

Bronchial Tree Anatomy and Grading

The human bronchi (grade 1) has about 24 branches from the alveoli.

The bronchus enters the lung through the hilum and is divided into lobular bronchus (level 2), 3 branches in the right lung, and 2 branches in the left lung.

The leaf bronchus is divided into segmental bronchi (grades 3 to 4), with 8 branches in the left lung and 10 branches in the right lung.

Segmental bronchi branching repeatedly into small bronchi (grades 5-10)

And then branched into bronchiole (grades 11 to 13),

The bronchioles branch into terminal bronchioles (grades 14 to 16).

From the leaf bronchus to the terminal bronchioles are the air-conducting parts in the lungs. The branches below the terminal bronchioles are the respiratory parts of the lungs, including respiratory bronchioles (grades 17-19), alveolar ducts (grades 20-22), alveolar sacs (grade 23), and alveoli (grade 24).

Basic Information

Chinese name: Bronchial tree

Pinyin: zh qì gun shù

English name: bronchial tree

Organ parts: trachea and bronchi

Organ shape: tree shape

Characteristics of Bronchial Tree Organs

The trachea and bronchus are the breathing passages of the human body, and the tree is a plant in nature. People associate the bronchus with the tree because the shape of the trachea, bronchi, and their branches is like a lush tree. However, the shape of this tree is inverted

Bronchial tree With the trachea on the trunk, the bronchial tubes and branches under the branches. In addition, the bronchial tree is hollow, and its lumen is a channel for airflow.

Bronchial tree organ function

The function should include two steps: gas exchange through the alveoli perfused oxygen in the atmosphere into the blood, and then transported by the blood to the tissues of the whole body; * blood brings carbon dioxide in the tissue to the lungs and is discharged from the body through gas exchange. To complete these two tasks, two pipes must be available in the lungs. One of them is a closed blood running pipeline, which is composed of the heart, arteries, capillary networks, and veins. The work of the heart provides the driving force for the blood. It is commonly referred to as the cardiovascular system and the circulatory system. The other tube of the lung is an open gas delivery tube system. Breathing movements carry fresh air into the body and expel carbon dioxide and the like out of the body. This airway system is composed of branching and subdividing of trachea, bronchi and bronchi. The length and thickness of the trachea vary according to gender and age. Adult men are about 11 cm long and women are shorter. The lower part of the trachea is divided into two left and right bronchial tubes. The right bronchus is thick and short, and it is vertical to the ground. Therefore, foreign objects entering from the trachea easily fall into the right bronchus. The left bronchus is thin and long, parallel to the ground, so foreign matter is not easy to enter.

Bronchial tree related imaging examination and application

CT manifestations of bronchial tree lesions and their applications:

1. Bronchial tree 1. tracheal enlargement

There are many reasons, including: (1) trauma, mostly caused by long-term intubation. (2) Tracheobronchomelacia can be caused by congenital or acquired factors. Congenital cartilage defects are also known as Ehlers-Danlos syndrome. Acquired diseases are often associated with long-term intubation. (3) Large tracheobronchial diseases are often complicated by recurrent respiratory tract infections, such as chronic cystic fibrosis, immunodeficiency, etc. Other reports suggest that men aged 30 to 40 without a clear history of infection may be associated with long-term smoking. There is also a congenital factor, called Mounier-Kuhn syndrome, which is rare. Dilation can affect only the trachea, but also the main bronchi and the lobe and segmental bronchi. Mostly due to cartilage ring and sarcolemmal developmental defects. The CT manifestations have certain characteristics. It can be seen that the enlarged tracheal diameter is more than 3cm, and the main bronchial tube diameter is more than 2.4cm.

In Mounier-Kuhn syndrome, there are too many myofascial tissues protruding from the cartilage ring, which makes the trachea "scalloped appearance", also known as "tracheal / bronchial diverticulosis", which is common in the posterior wall of the trachea. Spiral CT reconstruction images can obtain the overall understanding of the lesion range, and measure the diameter of the tube more accurately. By scanning the expiratory phase and the inspiratory phase separately, the compliance of the tube wall can be judged.

2. Bronchial tree 2. bronchiectasis

The bronchial wall loses its normal elasticity and forms an irreversible abnormal expansion of the lumen. It can be caused by congenital -trypsin deficiency. The most common cause is necrotizing bacterial infections at an early age. It can also be caused by chronic lung diseases such as tuberculosis and fibrosis. The results of the research by Grenier et al. Showed that the diagnosis and evaluation of bronchiectasis compared with bronchography by HRCT has a sensitivity of 96% and a specificity of 93%, which is significantly higher than that of conventional CT (60% to 80%), and is more than bronchial Patients without angiography have no pain, so it is now the preferred examination method. However, high-resolution CT has respiratory artifacts and scan intervals, and sometimes small bronchiectasis may be missed. Spiral CT is a continuous volume scan, which overcomes respiratory motion artifacts and can perform MPR, which is beneficial for continuous display of lesions.

Bronchial Tree Related Clinical Techniques

Thick body slices rarely show the false bronchus sign of the bronchus, but the conventional body slices have a thin layer on the mountain. Thick body layers are more likely to detect cancer-associated lesions: insufficient lung inflation, changes in vascular texture, atelectasis, destruction of lung tissue, focal inflammation, lymphangiitis, lymphadenopathy, and pleural changes. For bronchial central lung cancer, bronchial sleeve-like changes and lumen deformation can be shown. In addition, it also helps to identify the nature of cavities, which can better show the expansion of bronchial lumen and lesions. For patients with bronchiectasis and pulmonary insufficiency, the bronchial cavity is filled with mucus and luminal pressure, which provides more diagnostic basis than bronchial aura. The thicker tomography is more informative, so it is less expensive than conventional tomography and the patient's exposure is small.