The structure that lies between the trachea and bronchi is the:

The part of the conduction system that is located on the floor of the right atrium is the:

A. SA node. B. AV node. C. bundle of His. D. Purkinje network.

Patients often develop ________ mechanisms, or unconscious efforts to protect themselves from anxiety, guilt, and shame.

Fill in the blank(s) with the appropriate word(s).