Histology Guide

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Chapter 17 - Respiratory System

The respiratory system is responsible for taking in oxygen and expelling carbon dioxide. It can be divided functionally into two regions:

Respiratory epithelium is a pseudostratified ciliated columnar epithelium with goblet cells that lines much of the conducting passages.

Nasal and Oral Cavities

The nasal cavities provide an extensive surface area for removing debris, warming, and humidifying the air. The nasal and oral cavities are separated by the hard and soft palate.


The epiglottis is a flap located in the throat that covers the entrance to the larynx during swallowing.



The larynx is a hollow, tubular structure at the upper end of the trachea. It is involved in breathing and producing sound. The epithelial lining varies depending upon the region of the larynx.


The trachea (windpipe) is a fibromuscular tube supported by C-shaped rings of hyaline cartilage. It extends from the larynx toward the lungs.


The adult lungs are sponge-like organs. The main function of the lungs is to provide oxygen and remove carbon dioxide from blood.

Fetal Lung

The fetal lung is not capable of supporting respiration.