"If someone's airway is blocked with a blanket, for example, they are unable to expel CO2, which causes their CO2 blood levels to rise. Normally, this triggers a series of reactions that cause the individual to wake up and either re-position themselves so that they can breathe again, or cry out for help, like in the case of a baby," says author Gordon Buchanan, an associate professor of neurology at the University of Iowa. "However, in instances of SIDS and SUDEP, evidence is beginning to suggest that elevated CO2 doesn't trigger this wake-up response like it should, which can ultimately result in death."
Why a person would fail to wake up from increased CO2 is not fully understood, but a potential explanation is that a malfunctioning serotonin receptor in the midbrain may be responsible.
Neurons - Medulla - Regulation - Breathing - Ones
"Serotonin neurons in the medulla are involved in regulation of breathing, and we think the ones in the midbrain are involved in regulating a person's ability to wake up," says Buchanan. "In instances of SIDS and SUDEP, autopsies frequently reveal that there are abnormalities in the individual's serotonin system in the brain.
"It is very possible that there is a direct path by which CO2 is sensed by serotonin receptors in the midbrain, and when there is too much CO2 present, the brain reacts by waking up the individual," he says. "The existence of this...
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