One of the parts that makes up the respiratory system is the trachea, a tube that allows air to pass from the larynx to the bronchi.
In the next few lines we are going to learn a little more about what the trachea is like , what are the functions it has reserved and what type of diseases it can develop.

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What is the trachea?
The trachea is a ringed and cartilaginous tube that plays an essential role in the respiratory system: its most important function is to facilitate the movements of inspiration and exhalation.

It is located in front of the esophagus in its upper part and connects with the larynx in its lower part (where the cervical vertebra 6 or ‘C6’ is located). From there it descends inside the chest cavity to an area called the ‘mediastinum’, which is located in the middle of it.

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The 4 parts of the trachea
Now, we proceed to explain the different parts of the trachea according to its anatomy.

1. Bronchi
It is at this point where the trachea forks into two bronchi, just where the fifth dorsal vertebra (‘D5’) is located, and is connected to the lungs thanks to these two pathways.
Due to its strategic location and its important role in respiratory function, the lower part of the trachea is protected by the sternum bone, which is where the ribs meet, which in turn protect both lungs.

2. Rings
The trachea is flexible, it has a length of approximately 12 centimeters in an adult personand is divided into 16 sections or superimposed rings of 1.7 centimeters in diameter on average.
Inside, this tubular organ is covered with villi responsible for expelling any foreign body that is retained and that hinders the passage of air.

3. Adventitial
layer It is the outer layer that surrounds the entire diameter of the trachea, and that covers the cartilaginous rings in which it is divided.

These rings are not glued together, but are held together by an elastic membrane that allows them to stretch and contract.

4. Submucosal
layer The innermost layer of the trachea walls, which contains the cilia that retain mucus and harmful particles from the air.

The 5 functions of the trachea
As we anticipated before, the trachea has a vital function in breathing, which is divided into two opposite rhythmic movements, in addition to others.

1. Entry of air with oxygen
Thanks to its connection with the respiratory tract that lead to the outside (mouth, nostrils and, further inside, the larynx), the trachea allows the entry of air loaded with oxygen, which circulates through its interior until it ends into the lungs through the bronchi.

2. Hematosis
We call ‘hematosis’ the process of gas exchange that occurs inside the lungs, specifically in the alveoli (the small cavities where the bronchi end), when air with oxygen passes into the bloodstream.
Thus,At the same time that the oxygen makes this route , the carbon dioxide makes the opposite to be able to be expelled.

3. Expulsion of carbon dioxide
The consequent function of the trachea once hematosis has occurred is the exit of carbon dioxide to the outside.
In this way, it is sought that there is a balance between the levels of oxygen that enter the blood through the alveoli and those of carbon dioxide that is expelled .

4. Phonation
An important action that we humans perform and that distinguishes us from other living creatures is speech. However, this function would not be possible without the contribution of the trachea .
The phonation (or, so that we understand each other, the production of audible sounds) requires the work of the trachea, which is the part from which the air will be expelled towards the oral and nasal cavities.
Passing through the vocal cords, they will vibrate and the sound will be produced , which will then be modulated by other parts of the phonatory apparatus (tongue, lips and jaw).
After the formation of sounds, another process will take place, called ‘locution’, in which the trachea no longer intervenes; this generates the first sound.

5. Drainage of mucus and foreign substances
For its correct operation, it is ideal that the trachea is clear. Otherwise, when particles remain attached to their cilia (or villi), the trachea must get rid of them, to prevent them from descending into the pharynx. This happens the same with excess mucus when we catch a cold .

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5 diseases of the trachea (and other ailments)
Like any other part of the body, the trachea is not exempt from conditions that hinder the respiratory cycle, some of which may be hereditary.
Sometimes the severity is such that the patient is required to be intubated to be able to breathe or swallow normally.

1. Inflammation of the larynx and trachea
It is the mildest of the affections of the trachea but if it is not treated in time it can lead to more serious ones.

This infection can be caused by a virus that inflame the larynx and thus obstruct the normal passage of air through the trachea.
However, it can be treated without any problem using anti-inflammatories, which will be of greater or lesser power depending on the inflammation.

2. Tracheitis
It is an infection that tends to affect more in small children from 6 months and in adolescents up to a maximum of 14 years.
Tracheitis is triggered by the action of a bacterium (named Staphylococcus aureus), which originates after an infection in the respiratory tract , such as a winter cold.
An onset of tracheitis can be detected by attacks of dry cough, which appear continuously and suddenly. Although at first there is usually no presence of mucus, phlegm appears later, in addition to punctures in the sternum area.
This spasmodic cough is very annoying, especially when the symptoms worsen at night , preventing sleep.
If it is also the case that the larynx has also become inflamed, the person may suffer from hoarseness for a few days.

3. Tracheomalacia
This pathology of the trachea can have hereditary causes , and consists of a weakening of the walls of the tracheal tube, which causes the decomposition of the cartilage that forms the structure.
Tracheomalacia can occur as a result of a surgical intervention in the area, due to inflammation of the blood vessels that surround the trachea or after a long period of being intubated.
Despite its seriousness,its incidence is rather low and can be corrected by surgery .

4. Tracheoesophageal fistula
It is a malformation at the height of the throat, in the upper part of the esophagus and the trachea. These two sections are actually separate , but people with a tracheoesophageal fistula are born with a defect that makes them both connected.
The main affected by this pathology are usually neonates, but this condition can be reversed by subjecting them to surgery, whose procedure will vary in complexity depending on the degree of malformation, the health of the child, the professional’s assessment and optimism regarding their recovery . in the future.

5. Mounier-Kuhn syndrome
Its medical name is ‘tracheobronchomegaly’ and it is characterized by an abnormally large size of the trachea and bronchi , just as the name suggests.
This causes the patient to constantly present a picture of constant respiratory diseases, such as pneumonia, bronchitis or cough accompanied by blood.
If before we talked about a trachea diameter of 16 millimeters, in a case of Mounier-Kuhn Syndrome, it can measure up to 25.
This abnormality occurs due to a genetic cause and, if it appears, it does so around thirty.

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