Question

Lining of trachea is made up of _______.
A) Simple squamous epithelium
B) Simple cuboidal epithelium
C) Pseudostratified epithelium
D) Stratified cuboidal epithelium

Answer 1

Hint: Trachea is one of the parts of the respiratory system that functions as a connecting pipe between the lungs and larynx (voice box). It is a hollow tube like structure that allows air to pass through.

Complete answer
Let's study about each of the options mentioned above in detail to find out which one is capable enough to provide a protective shield to the organ.
Simple squamous epithelium is a kind of easily permeable layer. It is generally present within the organs that are concerned with frequent exchange of molecules. It uses a filtration or diffusion process to allow movement of specific particles. This kind of layer is commonly observed within blood capillaries or alveoli sacs that are concerned with frequent exchange of Oxygen or Carbon dioxide molecules. As trachea does not require frequent exchange of particles, therefore, it cannot be the part of this organ, therefore, A is an incorrect answer.
Simple cuboidal epithelium is a kind of layer that is concerned with absorption or secretion tasks. they are commonly found to form inner lineage of kidneys, pancreas, etc. which are absorbing and secreting organs of the body. Since, the trachea is nowhere concerned with absorption or secretion tasks so, it cannot form trachea’s inner lining. Thus, option B is also an incorrect answer.
Pseudostratified epithelium is a single cell layer specially the goblet cells. The Goblet cells are one to produce moisty fluid called mucus that attracts germs entering into the organ and thus purifies the tract. Also, it has ciliary muscles that perform a lashing movement making passage of air even easier through the Trachea. Since it is concerned with providing protection to the organ, we can say that the option C is the correct option.

Stratified cuboidal epithelium is a kind of layer that is again concerned with providing absorption and secretion services to the organ. however, this service is only for specific particles. Since, Trachea has got nothing to do with absorption or secretion purposes therefore, it cannot form the inner lining. So, D is an incorrect answer.

Note:
Trachea is a pipe- like organ connecting the two blades of lungs, thus, it interacts directly with the outer environment by giving pathway to atmospheric air for conduction of respiratory processes. Therefore, it has got to bear a kind of protective mechanism against germs coming along with oxygen, in its inner lining.