The endocrine system is made up of glands that secrete hormones to regulate various bodily functions. The main glands include the adrenal glands, which release epinephrine during the fight or flight response; the thyroid gland, which controls growth hormone secretion; and the thymus gland, which produces immune cells. These glands utilize feedback mechanisms to control hormone release and ensure balance, though imbalances can occur if a gland produces too much or too little of a certain hormone.

1. Life Science 4.3The Endocrine System

2. Objectives:Explainwhy the endocrine system is important to the body.Identify five glands of the endocrine system, and describe what their hormones do.Describe how feedback mechanisms stop and start hormone release.Name two hormone imbalances.

3. Hormones as Chemical MessengersEndocrine systemCollection of glands and groups of cells that secrete hormones.Glandgroup of cells that make special chemical messengers, called hormones, for your body.HormoneChemical messenger made in one cell or tissue that causes a change in another cell or tissue in another part of the body.

4. Adrenal GlandsEpinephrine – also known as adrenaline, is released in “fight or flight” response.Prepares you to fight or run from danger.

5. More Endocrine GlandsThyroid glandControls the secretion of growth hormones for normal body growth.Thymus glandProduces killer T cells that help destroy or neutralize cells or substances that invade your body.MetabolismSum of all the chemical processes that take place in an organism.

7. Controlling the Endocrine GlandsEndocrine glands control feedback mechanisms in the body.Occasionally, an endocrine gland makes too much or not enough of a hormone. For example, sometimes a child’s pituitary gland doesn’t make enough growth hormone. As a result, the child’s growth is stunted.Hormone Imbalances