air sac

• Poche ou cavité à paroi mince remplie d'air dans un organisme, en particulier chez les oiseaux (reliée aux poumons pour la respiration) et chez certains insectes ou végétaux, servant à la flottabilité, à la production de sons ou aux échanges gazeux.

A thin-walled, air-filled space or cavity in the body of an organism, particularly found in birds (connected to the lungs for respiration) and in some insects or plants, serving functions such as buoyancy, sound production, or gas exchange.

1. Anatomical structureB2formal

   A small, thin-walled cavity in the body, especially in the lungs of mammals or the respiratory system of birds, that facilitates gas exchange.

   sac aérien

   • The air sacs in the lungs allow oxygen to enter the bloodstream.
   • Birds have a complex system of air sacs that helps them breathe efficiently during flight.
   • Damage to the air sacs can lead to respiratory problems.

2. Plant structureC1formal

   A cavity filled with air found in some aquatic plants, providing buoyancy.

   sac aérifère

   • The air sacs in the seaweed help it float towards the sunlight.
   • Certain water lilies have air sacs in their stems to keep them upright.
   • The plant's air sacs allow it to survive in deep water.