«tasdiqlayman» Tabiiy fanlar fakulteti dekani K. Asqarov

Development[edit]
In the fourth week of development of the human embryo as the respiratory bud grows, the trachea separates from the foregut through the formation of ridges which eventually separate the trachea from the oesophagus, the tracheoesophageal septum. This separates the future trachea from the oesophagus and divides the foregut tube into the laryngotracheal tube.^[5] By the start of the fifth week, the left and right main bronchi have begin to form, initially as buds at the terminal end of the trachea.^[5]
The trachea is no more than 4mm diameter during the first year of life, expanding to its adult diameter of approximately 2cm by late childhood.^[2][3] The trachea is more circular and more vertical in children compared to adults,^[3] varies more in size, and also varies more in its position in relation to its surrounding structures.^[2]
Microanatomy[edit]
The trachea is lined with a layer of interspersed layers of column-shaped cells with cilia.^[3] The epithelium contains goblet cells, which are glandular, column-shaped cells that produce mucins, the main component of mucus. Mucus helps to moisten and protect the airways.^[6] Mucus lines the ciliated cells of the trachea to trap inhaled foreign particles that the cilia then waft upward toward the larynx and then the pharynx where it can be either swallowed into the stomach or expelled as phlegm. This self-clearing mechanism is termed mucociliary clearance.^[7]
The trachea is surrounded by 16 to 20 rings of hyaline cartilage; these 'rings' are incomplete and C-shaped.^[2] Two or more of the cartilages often unite, partially or completely, and they are sometimes bifurcated at their extremities. The rings are generally highly elastic but they may calcify with age.
Function[edit]
The trachea is one part of the respiratory tree that is a conduit for air to pass through on its way to or from the alveoli of the lungs. This transmits oxygen to the body and removes carbon dioxide.^[3]
Use in killing humans[edit]
Crushing the trachea is a common tactic for temporarily or permanently disabling another human and is taught in the military, martial arts and police forces around the world.
Clinical significance[edit]