Histology Testbank: Respiratory System 4a

Instructions: For each histology question, pick the one best answer. This histology test bank is also useful for the histology questions on the USMLE (USMLE step 1).

1.
Which cartilage of the larynx is made of elastic cartilage?
a. Thyroid cartilage
b. Cricoid cartilage
c. Arytenoid cartilage
d. Epiglottis
e. Corniculate cartilage

Answer: d

The larynx is composed of several cartilages. The thyroid cartilage, cricoid cartilage, arytenoid cartilages, corniculate cartilages and cuneiform cartilages are all composed of hyaline cartilage. The epiglottis is elastic cartilage. There is no fibrocartilage in the larynx.

2.
Which cell is rarely found in the alveolus?
a. Clara cell
b. Type I pneumocyte
c. Type II pneumocyte
d. Dust cell
e. Brush cell

Answer: e

The Clara cell is found in the terminal bronchioles. The type I pneumocyte is a squamous epithelial cell. It covers most of the surface of the alveoli. The type II pneumocyte is also called a septal cell. The type II pneumocyte secretes surfactant. The dust cell is also called the alveolar phagocyte. Brush cells are occasionally, but rarely, seen in the alveolar epithelium.

3.
What are the alveolar pores called?
a. Pores of Luschka
b. Pores of Descemet
c. Pores of Mall
d. Pores of Kohn
e. Pores of Disse

Answer: d

The alveolar pores are the pores of Kohn. These are openings between adjacent alveoli.

4.
What is the first portion of the respiratory tree where gas exchange can occur?
a. Alveolar duct
b. Alveoli
c. Alveolar sac
d. Respiratory bronchiole
e. Terminal bronchiole

Answer: d

The respiratory tract is made of branching structures, much like the branches of a tree. The trachea branches into two bronchi which branch into smaller bronchi. The bronchi ultimately branch into smaller bronchioles. Bronchioles are distinguished from bronchi in that they do not have cartilage and submucosal glands. The terminal bronchioles are the last part of the airway in which gas exchange does not occur. Terminal bronchioles lead to the respiratory bronchioles. The respiratory bronchioles are the first section of the respiratory tree that gas exchange can occur. The alveoli duct is analogous to a thoroughfare with many cul-du-sacs branching off of it. At the end of the alveoli duct is an alveoli sac. An alveoli sac is a cluster of alveoli, much like a cluster of grapes. Alveoli are individual sacs where gas exchange occurs.