Regulation

	III. Chemical Control Hormones * used by all organisms * similar to nerve control, however NEURONS are not used to control and coordinate all the body activities; chemicals called hormones are also used * hormones are also called chemical messengers * they are produced in glands which secrete them into the bloodstream; this transports the hormone to a TARGET TISSUE which will react a certain way * hormones can either simulate (start) or inhibit (stop) a reaction * hormones control-- 1) overall metabolism 2) maintenance of homeostasis 3) growth and reproduction 4) reproductive cycles A) Adaptations of Chemical Control 1) plants-- * plant hormones are chemicals produced by cells which affect growth and development of other cells * plant hormones are produced in areas of the plant that grow quickly (root tips, stems, buds, seeds) * a plant growth (mistakenly called movement) because of a stimulus is called a tropism phototropism--response to light geotropism--response to gravity hydrotropism--response to water thigmotropism--response to touch the plant hormones that are responsible for this kind of growth or "movement" are called AUXINS* 2) animals (in general)-- * different than chemical control in plants because there are certain tissues that produce specific hormones * these are found in ENDOCRINE GLANDS hormones are made in one place in the organism hormones carried by the circulatory system to their target tissues * animal hormones control specific tissues and have many, many different functions
Regulation



		hormones--the chemical messengers of the body; see how they were discovered