Alveolar macrophage

The third cell type present in the alveolus is the alveolar macrophage, which can be can also be found in the interalveolar septum. Because the surface of the alveolus is continuous with the exterior, these cells actually function outside the body. 1000x

The third cell type present in the alveolus is the alveolar macrophage, which can be can also be found in the interalveolar septum. Because the surface of the alveolus is continuous with the exterior, these cells actually function outside the body. 1000x

Type I cells (pulmonary epithelial cells) line the alveolus; their nuclei protrude into the alveolar space. Endothelial cell nuclei face the capillary lumen and are frequently curved to assume the shape of that lumen. Septal cells (type II alveolar cells) are large, vacuolated cells that bulge into the alveolus.

Type I cells (pulmonary epithelial cells) line the alveolus; their nuclei protrude into the alveolar space. Endothelial cell nuclei face the capillary lumen and are frequently curved to assume the shape of that lumen. Septal cells (type II alveolar cells) are large, vacuolated cells that bulge into the alveolus.

Capillaries form 80% of the wall of the alveolus and are supplied with deoxygenated blood by branches of pulmonary arteries. After oxygenation, blood is returned by the pulmonary venous system. The air-blood barrier consists of a simple squamous epithelium (type I) lining the alveolus and a simple squamous epithelium (endothelium) lining the capillary, along with their fused basal laminae.

Capillaries form 80% of the wall of the alveolus and are supplied with deoxygenated blood by branches of pulmonary arteries. After oxygenation, blood is returned by the pulmonary venous system. The air-blood barrier consists of a simple squamous epithelium (type I) lining the alveolus and a simple squamous epithelium (endothelium) lining the capillary, along with their fused basal laminae.

Alveolar macrophages are derived from monocytes and normally phagocytose foreign debris that reaches the lungs. During congestive heart failure, they phagocytose extravasated blood accumulating in alveoli and are then called “heart failure” cells.

Capillaries form 80% of the wall of the alveolus and are supplied with deoxygenated blood by branches of pulmonary arteries. After oxygenation, blood is returned by the pulmonary venous system. The air-blood barrier consists of a simple squamous epithelium (type I) lining the alveolus and a simple squamous epithelium (endothelium) lining the capillary, along with their fused basal laminae.