What is it called when oxygen passes into the capillaries that surround these sacs?

It's called alveoli when oxygen passes into the capillaries that surround these sacs

Technically it's breathing but the answer to that is aveoli while air passes through the capillaries what are the sacs you mean

Wetlands form where water and land meet. a lake with a wetland fringe can fill in with decayed plant and animal material to become a wet meadow. a pond can fill in to become a bog or fen. sediment can fill in a river marsh to become a swamp.flooding of coastal lowlands from rising sea levels has created broad coastal marshes that are protected from wave action by barrier islands or reefs. coastal wetlands also form when rivers deposit sediment as they reach the ocean. plants then take root and hold the soil firm against the forces of tides and waves.