type of pneumocyte

Features	Type 1 pneumocyte (squamous alveolar cell )	Type 2 pnemocyte (great alveolar cell, secrerory epithelial cell)
Numbers	97% of alveolar surface	3% of alveolar surface
Shape	Flat simple squamous epithelial cell	Low cuboidal cell
Cytoplasm	*little *few organelles -cluster around nucleus -small pnocytic vesicles	*large amount *many organells -large amount of mithocondria, ribosomes,ER, well develop golgi body (characteristic of secrerory cell)
Nucleus	Flat	Round
Cell division	*they are differentiated cells. *can’t divide	*can divide. *stem cell of both type.
Function	-small pnocytic vesicles >assist in turnover of pulmonary surfactant. >removal of small particles from	*secrete pulmonary surfactant -contain phospholipid, proeins and GAG -forms a film over the alveolar epithelium, > which reduce surface tension > prevents collapse of the alveolus during expiration.
Cell connection	Tight junction( among each other) -prevent leakage of tissue fluid into the alveolar cavity.	Tight junction -with type 1
Others	Provide very thin membrane -gaseous exchange occur	*have membrane limited multilamellar bodies( cytosome ) -exhibit many parallel membranes (lamellae) *theor free surface -bulge into the alveolar cavity -covered with short microvilli