What are the three most commonly identified classes of endogenous opiates?

A stiff dressing used for immobilization of various body parts is a:

A) sling B) clamp C) ratchet D) cast

A flexible instrument, passed through a body channels for withdrawal of fluids from or introduction of fluids into the body cavities, is called a:

A) cautery B) hemostat C) cystocentesis D) endotracheal tube E) catheter