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.
Anurse is caring for a client who is learning how to take care of a newly created colostomy. when observing a return demonstration of the colostomy irrigation, the nurse evaluates that more teaching is required when the client carries out what procedure?