Endocrine System Essay

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| The Endocrine System | | | | | Carson Neal P.2 | The endocrine system is one of the most complex body systems, and it is also one of the most intriguing. It is known as the second great controlling system of the body. Much like the nervous system sends electrical messages to control and coordinate the body; the endocrine system uses special chemicals called hormones to “communicate” messages to the body’s cells so that they can perform their actions and maintain homeostasis. A hormone is a specialized type of messenger molecule created and secreted by an endocrine gland, which is made up of a group of certain specialized cells. Hormones can nearly all be classified as either amino-acid based molecules or steroids. Endocrine glands are ductless; therefore their contents (hormones) are secreted directly into the bloodstream. Once hormones are released, they travel through the blood to a target organ, which they act upon. A target organ will respond to a hormone because it has special “receptors” for that hormone. Hormones each have their own specific shape and will therefore fit into certain receptors but not others. When the hormone binds to the receptor site, a molecule will either act as an “agonist” or an “antagonist”, or a combination of the two. Agonists are molecules that bind to the receptor site of a target organ and produce biological effects (physical changes) as a result. Antagonists are molecules that bind to the receptor site, but fail to trigger any biochemical effects. There are usually four things that can happen when hormone binding occurs: 1) Changes in plasma membrane permeability or electrical state. 2) Synthesis of proteins or certain regulatory molecules in the cell. 3) Activation or inactivation of enzymes. 4) Stimulation of mitosis. In other words, hormones bring about their effects on the body’s cells by altering

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