Question

Explain the difference in a person's respiratory movements when hyperventilation takes place in and out of a paper bag?

Answer 1

Hyperventilation is a reactive phenomenon performed by the lungs in response to abrupt fall in oxygen concentration in the blood. As a person hyperventilates inside a paper bag, the carbon dioxide build up is accumulated slowly in the blood. This activates the pons region in the brain to start hyperventilation. The lungs tend to hyperventilate but since the volume of air in the bag is fixed and the amount of oxygen is already depleted, the person actually inhales more and more carbon dioxide. This further suppresses the depth of ventilation and there are chances that the person suddenly faints.

On the other hand, when a person hyperventilates outside the bag, the pons region again activates the pulmonary vascular to perform rapid inhalations and exhalations. However in this case, the environment contains sufficient amount of oxygen and thus, the oxygen build up is eventually restored and hyperventilation ceases.