Type II cell

Type II cell

System	Respiratory system
Location	Alveoli of the lungs

Type II cells, also known as Type II alveolar cells or pneumocytes, are specialized cells located in the alveoli of the lungs. These cells play a crucial role in the respiratory system by producing and secreting pulmonary surfactant, a substance that reduces surface tension within the alveoli and prevents their collapse during exhalation.

Structure

Type II cells are cuboidal in shape and are found interspersed among the more numerous Type I alveolar cells, which are responsible for gas exchange. Type II cells are characterized by their prominent cytoplasmic granules, known as lamellar bodies, which store surfactant.

Function

The primary function of Type II cells is the synthesis and secretion of pulmonary surfactant. This surfactant is composed of lipids and proteins and is essential for maintaining the surface tension of the alveolar lining fluid. By reducing surface tension, surfactant prevents the alveoli from collapsing and ensures efficient gas exchange.

In addition to surfactant production, Type II cells also serve as progenitor cells for the alveolar epithelium. In response to lung injury, Type II cells can proliferate and differentiate into Type I cells, aiding in the repair and regeneration of the alveolar surface.

Clinical significance

Dysfunction or deficiency of Type II cells can lead to respiratory distress syndrome (RDS), particularly in premature infants, where insufficient surfactant production results in alveolar collapse and impaired gas exchange. Surfactant replacement therapy is a common treatment for RDS.

Type II cells are also involved in the pathophysiology of various lung diseases, including pulmonary fibrosis and acute respiratory distress syndrome (ARDS), where their regenerative capacity and surfactant production are compromised.

See also

• Type I alveolar cell
• Surfactant
• Respiratory system

External links

• Type II cell on WikiMD