Key Features of the Trachea Explained for Students
To understand what is trachea, let us go through the following information. The human trachea, also known as the windpipe, is a cartilaginous tube that connects the larynx to the bronchi of the lungs, enabling air to move through. It is found in almost all air-breathing species. From the larynx, the trachea divides into two main bronchi.
The cricoid cartilage binds the trachea to the larynx at the tip. The trachea is made up of a series of horseshoe-shaped rings that are bound vertically by overlying ligaments as well as at their edges by the trachealis muscle. While swallowing, the epiglottis seals the gap to the larynx.
In the 2nd cycle of embryo growth, the trachea starts to form, getting bigger and therefore more defined in its place over time. Column-shaped cells containing hair-like projections called cilia line the epithelium, which is surrounded by goblet cells that contain protective mucins.
Inflammation or infection of the trachea may happen as a consequence of a viral illness impacting other areas of the respiratory tract, including the larynx and bronchi, known as croup, which can cause a barking cough. A bacterial infection affects mainly the trachea, causing narrowing or obstruction.
Since the human trachea is such a vital part of the respiratory system, it may become blocked and restrict oxygen from accessing the lungs, necessitating a tracheostomy. In contrast, if mechanical ventilation is needed while a patient is medicated, a tube called intubation is introduced into the respiratory system trachea.
Trachea Structure
When you learn about the structure of the trachea, it becomes easier to understand what is trachea. The trachea structure or trachea anatomy shows that an adult is 1.5 to 2 centimeters (0.59 to 0.79 in) in diameter and 10 to 11 centimeters (3.9 to 4.3 in) in length, with males having a broader trachea than females. It starts at the base of the larynx and finishes at the carina, in which the trachea divides further into left and right key bronchi.
The trachea in human body is enclosed by 16 to 20 hyaline cartilage rings that are 4mm long, unfinished, and C-shaped in adults. Ligaments link the circles together. The trachealis muscle passes across the back wall of the trachea, linking the ends of the incomplete loops. The trachea anatomy displays that the trachea starts at the bottom of the laryngeal cricoid cartilage and finishes at the carina, in which the trachea splits across the left and right major bronchi. The respiratory system trachea starts only at the sixth cervical vertebra (C6) and ends at the fourth thoracic vertebra (T4), however, its location might change during breathing.
Cilia in Trachea:
A sticky mucous membrane layer lining the trachea is made up of cells with thin hairlike projections called cilia (Cilia in the trachea). To capture particles, the cilia expand into the trachea's channel (lumen). Mucus particles and molecules of water are secreted by cells and tubes in the mucous membrane.
Microanatomy
A surface of interspersed layers of column-shaped cells with cilia lines the trachea. Goblet cells, which seem to be column-shaped, glandular cells that are composed of mucins, the key part of mucus, are located in the epithelium. Mucus keeps the airways moist and secure.
Mucus surrounds the ciliated cells of the trachea, trapping inhaled foreign particles, which the cilia eventually waft upwards through the larynx, therefore the pharynx, where it could be swallowed or released as phlegm. Mucociliary clearance is the name given to this self-clearing process.
16-20 rings of hyaline cartilage cover the trachea; such 'rings' are unfinished and C-shaped. Two or maybe more cartilages frequently bind together, partially or entirely, and are occasionally differentiated at their extremities. The rings are usually very elastic, but as they age, they can calcify.
Clinical Significance
Inflammation and Infection:
Tracheitis is the swelling of the trachea, which is typically caused by an infection. Viruses are the most common cause, with bacterial infections appearing nearly exclusively in infants.
Infections of the trachea are more often characterized by inflammation of several other parts of the respiratory tract, including the larynx and bronchi, which is recognized as croup. Nevertheless, bacterial infections can impact the trachea on their own, but they are more commonly affected by the latest viral infection.
Croup is caused by parainfluenza viruses 1-3, with influenza viruses A and B often inducing croup but typically resulting in more severe infections. Bacteria such as Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, and Moraxella catarrhalis can also induce croup. Additional bacteria which can develop tracheitis in hospitalized patients include Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa.
Intubation:
The introduction of a tube down the trachea is known as tracheal intubation. This technique is widely used throughout surgery to guarantee that a patient gets sufficient oxygen while sedated. The catheter is mounted to a system that controls oxygenation, airflow, and a number of other parameters. This is frequently one of an anesthetist’s duties during surgery.
A tracheostomy is done to introduce a tube for breathing during an emergency and whenever tracheal intubation is considered impossible, typically when complex forms of surgery must be conducted and the airway must be held open. A tracheostomy is the provision of an opening by a tracheotomy.
Narrowing:
A narrowed or squeezed trachea might happen as a consequence of enlarged nearby trachea, lymph nodes, or nearby structure tumours, large thyroid goiters, or, less frequently, certain mechanisms including excessively swollen blood vessels.
A contraction of the trachea might be caused by bruising from intubation, or tracheobronchial injury, or inflammation involved with granulomatosis with polyangiitis (tracheal stenosis).
Stridor is a loud breathing sound that is invariably caused by obstruction. Bronchoscopy is a technique that involves inserting a camera through the mouth into another trachea that investigates the source of obstruction.
The treatment of obstructions is determined by the cause. Surgery, chemotherapy, or radiotherapy can be used to treat obstructions caused by cancer. Over the barrier, a stent might be inserted. Benign lesions, including scarring-induced narrowing, are more prone to have been surgically removed.
FAQs on Trachea: Structure, Functions, and Significance
1. What is the trachea and where is it located in the human body?
The trachea, commonly known as the windpipe, is a cartilaginous tube that forms a crucial part of the respiratory system. It is located in the neck and chest, extending from the bottom of the larynx (voice box) down into the chest cavity, where it divides into the two primary bronchi that lead to the lungs. It is positioned directly in front of the esophagus (food pipe).
2. How is the trachea structured to support its function?
The trachea's structure is uniquely adapted for airflow and protection. It is composed of 16-20 C-shaped rings of hyaline cartilage stacked vertically. This cartilage provides rigidity, ensuring the airway remains open (patent) for air to pass through. The inner surface is lined with a special tissue called pseudostratified ciliated columnar epithelium, which contains mucus-producing goblet cells that are essential for trapping debris.
3. What are the primary functions of the trachea?
The trachea has several vital functions in the respiratory system:
- Air Conduction: It serves as the main passageway for air to travel from the upper respiratory tract to the lungs during inhalation and back out during exhalation.
- Protection: Its mucous lining and cilia form the mucociliary escalator, which traps dust, pollen, and pathogens and moves them upwards and out of the airways.
- Air Conditioning: As air passes through, the trachea helps to warm, clean, and humidify it before it reaches the delicate tissues of the lungs.
- Cough Reflex: The smooth muscle in the trachea can contract forcefully to increase the velocity of air, aiding in the expulsion of irritants during a cough.
4. Why are the cartilaginous rings of the trachea C-shaped and not complete circles?
The C-shape of the tracheal rings is a critical design feature. While the hard, cartilaginous front provides support to keep the airway from collapsing, the open part of the 'C' faces the esophagus. This soft, muscular back allows the esophagus to expand into the space of the trachea when a large bolus of food is being swallowed, preventing choking and facilitating digestion without compromising the airway.
5. How does the trachea protect the lungs from foreign particles?
The trachea has a sophisticated self-cleaning mechanism called the mucociliary escalator. Goblet cells in its lining secrete a sticky mucus that traps inhaled foreign particles like dust, bacteria, and allergens. This mucus layer is constantly propelled upwards towards the pharynx by the coordinated, wave-like beating of tiny hair-like structures called cilia. Once it reaches the throat, the mucus can be either swallowed or coughed out, effectively clearing the lower respiratory tract.
6. What is the relationship between the larynx, trachea, and esophagus?
The larynx (voice box) sits at the top of the trachea and houses the vocal cords. The trachea begins just below it, acting as the main airway to the lungs. The esophagus is the tube for food and liquids and runs parallel and directly behind the trachea. A flap called the epiglottis, located at the top of the larynx, closes over the trachea during swallowing to ensure food correctly enters the esophagus and not the airway.
7. What happens if the trachea gets blocked?
A blocked trachea is a life-threatening medical emergency known as an airway obstruction. If the passage of air to the lungs is cut off, the body is deprived of oxygen (a condition called asphyxia). This can quickly lead to loss of consciousness, brain damage, and death if the obstruction is not removed immediately. This is why immediate first aid, such as the Heimlich manoeuvre, is critical in choking incidents.
8. Does the trachea play any role in the digestive system, such as carrying food?
No, the trachea is exclusively part of the respiratory system and its sole purpose is to transport air. It plays no role in digestion. The tube responsible for carrying food and liquid from the mouth to the stomach is the esophagus. A common misconception arises because they are located next to each other, but their functions are entirely separate and regulated by the epiglottis to prevent food from entering the airway.
