Gas glands are cells that fill the swim bladder with oxygen in physoclists (bony fish with a closed swim bladder ). The gas glands are located on the swim bladder and anaerobically break down glucose into lactate and carbon dioxide. This anaerobic breakdown of glucose is maintained even with a good oxygen supply. This makes the blood very acidic and oxygen no longer binds to hemoglobin. This is known as the root effect . The increased lactate concentration also leads to the so-called "salting out effect" and the solubility of all gases in the blood is reduced. The oxygen then diffuses into the swim bladder and this can be filled under high pressure.
In addition, a miracle net ( rete mirabile ) ensures that lactate and carbon dioxide stay close to the swim bladder via a countercurrent circuit. The inlet and outlet capillaries are right next to each other and the concentration gradient keeps the glucose breakdown products in the area.
Gas glands in the eye
In fish eyes, the gas glands also serve to acidify, here the oxygen supply to the retina is maintained. Due to the acidification, however, the values here are not as low as with the swim bladders of the Physoclists. This ensures the continued functionality of the retina, as it is not able to tolerate extremely low pH values.
- Heldmeier, Neuweiler: Comparative animal physiology.
- Penzlin: Textbook of Animal Physiology.