Why lungs are divided into very small sac-like structures??

1.	Why lungs are divided into very small sac-like structures??
Answer» Thanks..... Lungs are divided in sac like structures to increase the surface area for exchange of gases .And these sac like structures are called alveoli Because in our body there is neccesary to store some oxygen gas in our lungs to use it in worst time so that the lungs is divided into two sac like structures

Discussion