The windpipe (trachea) is a tube of 12 cm length whcih connects the larynx to the principal bronchi that lead to the lungs.
The tracheal functions comprises air flow into the lungs, mucociliary clearance, and humidification and warming of air.
Mucociliary clearance is done by kinocilia and goblet cells in the mucosa, by tracheal glands.
Development of trachea is from the endodermal lining of the foregut in interaction with the visceral mesoderm.
During adult life, stem cells which are having different types is reside in the mucosal epithelium and glandular ducts.
Anatomy and Physiology of Trachea
Anatomy of the Trachea
- The trachea has a long tube that extends from the pharynx and larynx till the bronchi of the lungs.
- It is an inner diameter of about 25.4 millimeters (1.00 in) and also a length of about 10 to 16 centimeters.
- It started from the lower border of the larynx, level with the sixth cervical vertebra, and bifurcates into the primary bronchi of the vertebral level of thoracic T5, or two vertebrae lower or higher, it is depending on breathing.
- Top of the trachea and bottom of the larynx is found the cricoid cartilage, the only complete ring of cartilage found in the trachea.
- The tube is extending downward throughout the length are about 15 to 20 incomplete C-shaped cartilaginous rings that reinforce made up the outer structure and shape of the trachea, leaving a membranous wall on inside of the tube.
- The hylaine cartilage the present in trachea, which is simple, transparent, and made primarily of collagen.
- The trachealis muscle connects at the ends of the incomplete rings of cartilage and it contracts during coughing, reducing the size of the tracheal lumen, to increase the air flow rate.
- The esophagus is lies behind the trachea. The function of the incomplete cartilaginous rings to allow the trachea to collapse slightly so that food would be passed down the esophagus after swallowing.
- The epiglottis function as closes the opening to the larynx during swallowing of food material to prevent swallowed matter from entering the trachea.
Physiology of the Trachea
- This mucus and cilia of the trachea form the mucocilliary escalator, that lines the cells of the trachea with mucus to trap inhaled foreign particles/material, then waft upward toward the larynx and then the pharynx where it would be either swallowed into the stomach (destroyed by acid) or expelled as phlegm.
- The important function of the trachea is the mucocilliary escalator and it is also considered a barrier component of the immune system which preventing pathogens from entering into the lungs.
- The epithelium and the mucocilliary ladder would be damaged by smoking tobacco and alcohol consumption, and person suffers pneumonia (an infection of the alveoli of the lungs) from bacteria in the upper respiratory tract.
- As the zone of the lungs, the trachea is having an important function in warming and moistening air before it would be reached into the lungs.
- The trachea is considered as a part of normal anatomical dead space (space in the airway that is not involved in alveolar gas exhange) and its volume to be contributed to calculations of ventilation and physiological (total) dead space.
- Alveolar is not considered is dead space, a term that refers to alveoli that do not prticipate in gas exchange due to damage or lack of blood supply.