BIOL 1107 Lecture Notes - Lecture 49: Thyroid, Anabolic Steroid, Parathyroid Gland
Document Summary
Animals use at least six major types of chemical signals. Hormones are chemical signals that are present in tiny concentrations and travel throughout the body to affect target cells. The information carried by hormones helps animals develop as embryos, undergo sexual maturation, respond to environmental change, and achieve homeostasis. The production of a hormone is tightly regulated by input from the nervous system and by other hormones. Some hormones bind to receptors inside target cells and change gene expression. Other hormones bind to receptors at the cell surface and lead to changes in protein activation. A group of organs and cells called the endocrine system produces chemical signals and secretes them into the bloodstream. They circulate through the blood or other bodily fluids and have a relatively long-lasting effect on distant target cells. In combination, animal nervous systems and endocrine systems process and respond to information about the environment.
