The+Endocrine+System

[Bao] **__THE ENDOCRINE SYSTEM __** The endocrine system acts with the nervous system to control body movements and activities (“Endocrine System”). It is made up of **glands** that produce chemical signals called hormones that help for growth, development and maintain homeostasis (Nowicki 904). These glands are found in many different places in the body (Nowicki 896). They release hormones into the bloodstream to be carried around the body and interact with many different cells during the journey (Nowicki 896). But they on ly join with the cells that have matching receptors (Nowicki 896). They will combine with that cell and it will make certain types of enzymes or proteins (Nowicki 896).

**__Structure __** The major organs of the endocrine system are mainly glands, which include hypothalamus, pituitary, thyroid, parathyroids, adrenals, pineal body and the reproductive organs (Rieser). Each gland makes hormones that target different cells at different places in the body (Nowicki 898). A few of these glands make **releasing hormones**, hormones that cause other glands to release their hormones (Nowicki). The **hypothalamus** is a section in the middle of the brain that has a main function of maintaining homeostasis (Bailey). It makes hormones that cause the pituitary gland to release its hormones (Nowicki 898). You can find more detailed information on the functions of the hypothalamus on this website []. The **pituitary gland** is a gland also in the middle of the brain producing hormones that help control growth, reproduction and body temperature (Nowicki 898). Another function of the pituitary gland is making hormones that control the water concentration in blood called osmoregulatory (Nowicki 898). Some of these hormones initiate other smaller glands and the pituitary is also a place where hormones produced by the hypothalamus go through before entering the bloodstream (Nowicki 898). The hypothalamus is a part of both the nervous and endocrine system. In the nervous system, it receives information from sensory organs, sorts and interprets them (Nowicki 900). In the endocrine system, it makes releasing hormones that affect tissues and other glands (Nowicki 900). On the right below is a diagram of the hypothalamus and pituitary gland location (“Location of the components…”). And more information about the anatomy of the endocrine system here []. (“Chapter 2: The Biolo gical Basis of Behavior”) (“Location of the components…”)

**__Hormones __** **Hormones ** are the chemical signals made by the glands of the endocrine system. There are two types of hormones: steroid hormones and nonsteroid hormones (Nowicki 896). Steroid hormones are made up of cholesterol, a type of lipid while nonsteroid hormones are made up of one or more amino acids (Nowicki 896). Steroid and nonsteroid hormones work with target cells in different ways (Nowicki 897). Target cells are cells that have matching receptors with certain hormones (Nowicki 896). To enter its target cells, the steroid hormone diffuses through the cell membrane and once inside, it sticks itself to the receptor protein of that cell (Nowicki 897). It then carries the hormone to the cell’s nucleus and binds with its DNA and this makes the cell produce the right protein for that part of DNA (Nowicki 897). (“Endocrine System”) Instead of entering the target cells, the nonsteroid hormones bind to t he receptor on the cell membranes to activate molecules inside the cells and cause chemical reactions to happen (Nowicki 897). These molecules then react with other molecules in the cell to start other chemical reactions or activate a gene in the nucleus (Nowicki 897). <span style="display: block; font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 150%; text-align: justify;">Hormonal imbalances can lead to bad consequences (Nowicki 901). Hormones are to maintain homeostasis, therefore if there is too much or too little, it can affect the body. If the hormone continues to be produced after reaching its ideal condition for maintaining homeostasis, it can cause diseases and illnesses. For example, diabetes is caused by the pancreas not releasing the right amount of insulin and glucagon that control sugar concentration in blood (Nowicki 901). You can read more about diabetes on here []. <span style="display: block; font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 150%; text-align: justify;">The endocrine system also uses a process called negative feedback to maintain homeostasis (Nowicki). Feedback loops are body responses when internal conditions are far above or far below the ideal condition for maintaining homeostasis. There are two kinds: positive and negative feedback. The negative feedback makes your body sweat so it cools down because the temperature is too high. Positive feedback can make the blood clots in your body warmer because the body temperature is too low. For more information on negative feedback, go here []. This is a diagram of a cycle regulating blood temperature. <span style="color: black; font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 115%;">(“ <span style="color: black; font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 115%;">All Lives Seek Balance: Homeostasis”).

<span style="display: block; font-size: 12pt; line-height: 200%; margin-left: 36pt; text-align: center; text-indent: -36pt;"> <span style="color: black; display: block; font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 24pt; margin-bottom: 0cm; text-align: center; text-indent: -36pt;">Works Cited

<span style="color: black; font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 14.25pt; margin-bottom: 0cm;"> "All Lives Seek Balance: Intro to Homeostasis." //Morning Earth Connects & Celebrates Arts & Ecology//. 2005. Web. 15 May 2011. < [] >.

<span style="color: black; font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 14.25pt; margin-bottom: 0cm;">Bailey, Regina. "Hypothalamus." //Biology//. Web. 15 May 2011. < [] >.

<span style="color: black; font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 14.25pt; margin-bottom: 0cm;">Carter, J. S. "Endocrine System." //Biology at Clermont College - University of Cincinnati//. 2 Nov. 2004. Web. 14 May 2011. < [] >.

<span style="color: black; font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 14.25pt; margin-bottom: 0cm;">"Chapter 2: The Biological Basis of Behavior." //Psychology - An Introduction//. Web. 15 May 2011. < [] >.

<span style="color: black; font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 14.25pt; margin-bottom: 0cm;">Hicks, Rob. "BBC - Health: Causes of Diabetes." //BBC - Homepage//. BBC. Web. 15 May 2011. < [] >.

<span style="color: black; font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 14.25pt; margin-bottom: 0cm;">"Homeostasis: Negative Feedback, Body Temperature, Blood Glucose." //Science Aid: High School, A Level and GCSE Science//. Web. 15 May 2011. < [] >.

<span style="color: black; font-family: 'Times New Roman',serif; font-size: 12pt;">"Location of the Components of the Hypothalamic-pituitary-adrenal (HPA) Axis." //NIAAA Home//. Feb. 2001. Web. 15 May 2011. < [] >. Nowicki, Stephen. //"The Endocrine System and Hormones".//

<span style="color: black; font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 18pt; margin-bottom: 0cm; text-align: justify;">Nowicki, Stephen. "The Endocrine System and Hormones". McDougal Littell Biology. Evanston, IL: McDougal Littell, 2008. 858-61. Print.

<span style="font-family: 'Times New Roman',serif; line-height: 14.25pt; margin-bottom: 0cm;"> Rieser, Marianne. "Anatomy of the Endocrine System." EMedicineHealth. Web. 15 May 2011. < [] >.