The 𝐄𝐏𝐈𝐆𝐋𝐎𝐓𝐓𝐈𝐒 is a cartilaginous structure at the posterior of the tongue that closes when you swallow to keep food and liquids out of your airway. A series of elastic cartilages provide semi-rigid support to the epiglottis.

The 𝐓𝐑𝐀𝐂𝐇𝐄𝐀 is a passage that connects the larynx to the lungs allowing the passage of air. The respiratory epithelium found in this structure is a ciliated pseudostratified columnar epithelium with goblet cells resting on a thick basement membrane. It protects the lungs from irritants and secretes mucus to trap particles and prevent them from traveling further down respiratory passages.

The 𝐀𝐋𝐕𝐄𝐎𝐋𝐈 are the major sites of gas exchange. Their presence increases the lung’s surface area to maximize gas exchange, thus possessing a lining of thin squamous epithelium.

REFERENCES
BD Editors, (2019). Pseudostratified Columnar Epithelium. Retrieved from https://biologydictionary.net/pseudostratified-columnar-epithelium/

Brandt JP, Mandiga P. Histology, Alveolar Cells. [Updated 2021 Apr 25]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557542/

Cleveland Clinic, (2020). Respiratory System. Retrieved from https://my.clevelandclinic.org/health/articles/21205-respiratory-system#:~:text=The%20respiratory%20system%20is%20the,waste%20gases%20like%20carbon%20dioxide.

Histology Guide. Retrieved from https://histologyguide.com/slidebox/17-respiratory-system.html

Kia’i N, Bajaj T. Histology, Respiratory Epithelium. [Updated 2021 May 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK541061/