air sac
Avian respiratory cavity
An air sac is a thin-walled cavity filled with air.
In birds, air sacs connect to the lungs and extend into the bones, enabling their highly efficient respiratory system.
Insects have similar structures as part of their tracheal breathing apparatus.
In mammals, the term sometimes refers to the alveoli—the tiny sacs in the lungs where gas exchange occurs.
Respiratory chest organs
- gas exchangeTransfer of respiratory molecules
- respirationGas exchange in organisms
- bronchiolesSmallest respiratory passages
- oxygenElement eight, colorless gas
carbon dioxide · pulmonary · bronchi · trachea · inhalation · exhalation · ventilation · diffusion
Aerial journey by aircraft
- respirationGas exchange in organisms
- syrinxBird's sound-producing organ
- buoyancyFluid's upward resistance
- thermoregulationMaintaining stable internal heat
ornithology · dinosaur · pterosaur · vocalization · diving bird
External respiratory aperture
- respirationGas exchange in organisms
- exoskeletonExternal skeletal structure
- ventilationCirculation of fresh air
- grasshopperJumping insect, long legs
locust · beetle · caterpillar · metamorphosis
Fish buoyancy organ
- floatationCapacity to stay buoyant
- bladderOrgan holding urine
- kelpLarge brown marine algae
- seaweedSaltwater aquatic plants
neutral buoyancy · inflation · deflation · aquatic · gas-filled · cephalopod · buoyant
lungs
Respiratory chest organs
- gas exchangeTransfer of respiratory molecules
- respirationGas exchange in organisms
- bronchiolesSmallest respiratory passages
oxygen · carbon dioxide · pulmonary · bronchi · trachea · inhalation · exhalation · ventilation · diffusion · capillaries
flight
Aerial journey by aircraft
- respirationGas exchange in organisms
- syrinxBird's sound-producing organ
- buoyancyFluid's upward resistance
thermoregulation · ornithology · dinosaur · pterosaur · vocalization · diving bird
spiracle
External respiratory aperture
- respirationGas exchange in organisms
- exoskeletonExternal skeletal structure
- ventilationCirculation of fresh air
grasshopper · locust · beetle · caterpillar · metamorphosis
swim bladder
Fish buoyancy organ
- floatationCapacity to stay buoyant
- bladderOrgan holding urine
- kelpLarge brown marine algae
seaweed · neutral buoyancy · inflation · deflation · aquatic · gas-filled · cephalopod · buoyant
- egg biologyegg, eggshell, egg white, egg yolk, yolk
- pollenpollen, pollen grains, pollen grain, bee pollen, grass pollen
- sacspouch, bladder, vesicle, bursa, cyst
- swim bladdersswim bladder, oval window
- poultrychicken, hen, turkey, duck, goose
- bird breedingegg, nest, hatch, chick, hatching
air sacblood vessel
Tube conveying circulation
cyst · bladder · lymph node · amniotic sac · yolk sac