All the neurons in our brains transmit electrical signals. The exchange of signals generates heat. The heat could be indirectly reduced by blood circulation. However, the nasal cavity and paranasal sinuses are more direct mechanism that can dissipate the heat, functioning as a cooling fan in a computer.
The heat generated from the brain while carrying out the vital functions to sustain life is cooled off by the air ventilation inside the nasal cavity and sinuses. That is to say, they are biological anti-overheating device by air cooling. The three nasal turbinates serve as anatomical structure to increase the surface where heat exchange occurs in the anti-overheating device.
The narrow inter-connecting passage between the nasal cavity and paranasal sinuses can be explained by the body’s attempt to maximize Bernoulli's effect. The effect would boost the air circulation inside the paranasal sinuses through nasal breathing.
The speed of air flow increases through the narrow ducts, connecting to the paranasal sinuses, where negative air pressure is generated by exhalation through the nose. This facilitates air ventilation. For that reason, surgical procedures of enlarging the ducts must be voided.