What does the prefix "endo-" refer to in medical context?

The prefix "endo-" is derived from Greek, meaning "inside" or "within." In a medical context, it is commonly used to refer to structures or processes that occur internally. For instance, "endoscopy" pertains to the examination of the inside of the body using an instrument, and "endocrine" describes glands that secrete hormones directly into the bloodstream. Understanding this prefix helps clarify many medical terms that involve internal processes or organs, making it essential for effective communication in healthcare settings.