Timmy is a cantankerous toddler who has just threatened that he will hold his breath until Mom gives him some chocolate. His mother refuses to be manipulated and watches in amusement as Timmy stubbornly refuses to breathe. To her horror, Timmy loses consciousness and collapses onto the floor. Her cousin, who is enrolled in a course for emergency medical technical (EMT) training, is visiting, and

tells her there is no need to call for an ambulance. Why did Timmy lose consciousness? Should his mother trust her instincts and call for help and begin CPR, or should she listen to her well-meaning but young and inexperienced cousin? Explain.

What will be an ideal response?


Timmy loses consciousness due to hypoxia in his brain. There is no need for alarm, because the loss of consciousness indicates mainly that cerebral activity has decreased. The parts of the brain involved in respiratory control are in the brain stem. As long as Timmy was awake and determined, his cerebral signals were able to inhibit brain stem control of pulmonary ventilation. Once he loses consciousness, however, the respiratory control areas are released from inhibition and he starts breathing again. Soon normal oxygen content in the brain will be restored, and Timmy will wake up.

Anatomy & Physiology

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