Question

Squamous epithelium is found in
A. Lung alveoli
B. Trachea
C. Intestine
D. Oviduct

Answer 1

Hint: Squamous epithelium is made up of large flat cells in contact with the basal lamina i.e. one of the two-layer of the basement membrane of the epithelium. These types of membranes are permeable and located where small molecules need to pass quickly through the membrane either via diffusion of filtration.

Complete answer:
A. Lung alveoli- Lung alveoli composed of an epithelial layer of simple Squamous epithelium which is very thin containing flat cells, and an extracellular matrix that is surrounded by capillaries. The epithelial layer is the part of the alveolar membrane which is also known as the respiratory membrane allowing the exchange of gases.
B. Trachea- The trachea which is the conducting passageway of the respiratory system is lined by the pseudo stratified columnar epithelial tissue, which is ciliated and having mucus-secreting goblet cells which help in trapping foreign substances.
C. Intestine- Intestine is lined by simple columnar epithelium which mainly consists of absorptive cells (enterocytes), with scattered cells and also enteroendocrine cells. This epithelium mainly lined the organs of the digestive tract. It primarily functions in absorbing nutrients from the lumen of the intestine.
D. Oviduct- Oviduct or fallopian tube is lined by ciliated columnar epithelium with secretory cells and it is folded out in the lumen so that the ovum always remains in the lumen close to the cilia for transport to the uterus.

Hence, the correct answer is option (A).

Note: As we know alveoli are the site for the exchange of gases in the lungs because quick diffusion is required between the alveoli and capillaries for that permeable, thin membrane is needed that is why alveoli are lined with Squamous epithelium so that easy gas exchange takes place to and from the bloodstream.