You have responded to a local pool for a drowning patient. lifeguards have pulled the patient out of the pool prior to your arrival. you find the 16-year-old patient unresponsive with agonal respirations and a weak carotid pulse. what is your first action?

answer: the blood-brain barrier is a layer of specialized membranes and cell processes designed to keep undesirable substances from passing from the bloodstream into the precious tissues of the brain. while the blood-brain barrier does keep most bad things out of the central nervous system, it is not impermeable.

explanation:

he is very short, and he can only reach halfway up on the elevator buttons. but on a rainy day, he has his umbrella with him, and he uses it to poke the button at the top.