type II pneumocyte

cell

Also known as: granular pneumocyte

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

July 14, 2026

Quick Summary

Type II pneumocytes are cuboidal cells found in the walls of the pulmonary alveoli, which are the tiny air spaces in the lungs where gas exchange occurs. These cells cover a small portion of the alveolar surface, with type I pneumocytes covering the majority.12

The primary function of type II pneumocytes is to produce and secrete pulmonary surfactant. This substance is crucial for reducing the surface tension within the alveoli, preventing them from collapsing, especially during exhalation. Without surfactant, significant force would be needed to re-expand the alveoli, hindering breathing. Before release, surfactant is stored within the type II cells in structures called lamellar bodies.12

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

2 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

human respiratory system
The gas-exchange region
…more cuboidal cell type, the type II pneumocyte, covers the remaining surface. The type I cells form, together with the endothelial cells, the thin air–blood barrier for gas exchange; the type II cells are secretory cells. Type II pneumocytes produce a surface-tension-reducing material, the pulmonary surfactant, which spreads on the…
Read More
…more cuboidal cell type, the type II pneumocyte, covers the remaining surface. The type I cells form, together with the endothelial cells, the thin air–blood barrier for gas exchange; the type II cells are secretory cells. Type II pneumocytes produce a surface-tension-reducing material, the pulmonary surfactant, which spreads on the…
Read More

pulmonary alveolus
…walls are a group called granular pneumocytes (Type II cells), which secrete surfactant, a film of fatty substances believed to contribute to the lowering of alveolar surface tension. Without this coating, the alveoli would collapse and very large forces would be required to re-expand them. Another type of cell, known…
Read More
…walls are a group called granular pneumocytes (Type II cells), which secrete surfactant, a film of fatty substances believed to contribute to the lowering of alveolar surface tension. Without this coating, the alveoli would collapse and very large forces would be required to re-expand them. Another type of cell, known…
Read More