AP Biology Chapter 45 Guided Reading
What is a hormone?
hormones are chemical signals that are secreted into the cirulatory system and communicate regulatory messages within the body.
Why does a hormone elicit a response only with target cells?
A hormone may reach all parts of the body, but only specific target cells respond to specific hormones.
The body has two long-distance regulating systems. Which involves chemical signals by hormones?
What is the other major communication and control system?