1. Endocrine System Ch. 18 Sect 3
The Endocrine System consists of groups of organs and tissues that release chemical messages into the bloodstream.
Endocrine glands – endocrine tissues that secrete chemicals.
Hormones – a chemical that is produced by an endocrine gland in one part of an organism and is carried in the bloodstream to another part of the organism.
Chemical messages are sent less often then electrical messages (nervous system) and last longer.
Ex: Nervous system message might cause you to move your body. Endocrine system message might cause you to grow taller.

2. Endocrine Glands and Their Hormones

3. Hormones
Hormones affect the functions of organs and tissues by carrying messages to specific cells called target cells.
Target cells have certain receptor proteins that attach the hormones.
Once the hormone binds with the target cells, it delivers the message and the target cell responds by taking a specific action.

4. Hormone Path

5. Endocrine System & Homeostasis
Glands help maintain homeostasis by releasing hormones in response to stimuli.
Hormones change the function for other tissues and organs in the body that regulate internal condition.
Negative Feedback – is a control system where the effect of a hormone inhibits further release of the hormone.
Positive Feedback – is a control system in which the effect of a hormone causes more of the hormone to be released.

6. Negative Feedback

7. Positive Feedback