The human body is full of chemistry. There are many chemicals throughout the body that control homeostasis. The endocrine system is the main system involved in secretion of chemicals called hormones. Glands located all over the body help to secrete hormones. Parts of the brain aid in this process as well. Hormones are chemicals which act as tiny little messengers that go throughout the whole body and control aspects you wouldn't think are controlled by horomones. Each specific horomone has its own task and, if not completed correctly, homeostasis would not be maintained.

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The organs involved in the endocrine system are shown in the diagram above. Each gland secretes their own specific hormones. Endocrine glands secrete their hormones directly into the blood, but some of the organs secrete their hormones into ducts, called exocrine glands. There are four classifications of hormones. Amines come from amino acids tyrosine and trytophan. Proteins and polypeptides are another class. Polypeptides are big proteins. Glycoproteins are hormones that are a protein and one or more carbohydrates. Steriods come from cholesterol and are considered hormones are well. Now, there are different hormones made in different endocrine organs. Each hormone has its own responsibility throughout the body to maintain homeostasis. Nerves are stimulated somewhere in the body and that sends a message to the brain to release neurotransmitters. Neurotransmitters can be chemicals that alter parts of the body as well as hormones. If the hormones work together, they are synergistic; if they work in the opposite ways of each other, they are antagonistic. If a target cell's chemical level goes below normal, the endocrine system sends out a hormone to bring that chemical level back up to normal by affecting the target cell. The blood stream acts as the main way of transportation for hormones.

The pituitary gland located in the middle of the brain, is an important organ for the endocrine system. There are two parts to the pituitary gland, the anterior and posterior. The hypothalamus, which is right above the pituitary gland, secrets hormones into the posterior pituitary gland which then stores the hormones. The anterior pituitary gland secretes and makes its own hormones. These tiny glands inside the middle of the brain have such a huge impact on the entire body.

The anterior pituitary makes six main horomones. Growth hormone (GH), supports overall growth of tissues and organs. Thyriod-stimulating hormone (TSH), helps the thyroid to release and secrete it's own hormones. Adrenocorticotropic hormone (ACTH), aids the adrenal cortex to secrete glucocorticoids. Prolactin (PRL), has a various amount of areas it affects. The PRL helps stimulate milk control in the mammary glands, the kidneys, and the male reproduction system. Follicle-stimulating hormones (FSH), helps the growth of sperm cells and ovarian follicles. Together FSH and luteinizing hormone (LH), are called gonadotropic hormones. LH help to start the process of sex hormones, testosterone in males, and ovulation in females. The anterior pituitary secretes hormones that affect alot of the other glands in the endocrine system.

The posterior pituitary glad has only two main hormones it secretes. Oxytocin is one of the hormones that affects the reproductive organs of males and females. In females, oxytocin helps to stimulate uterine contractions during labor, and the stimulate mammary glands as well. When a male ejaculates, there is a rise in oxytocin. Antidiuretic hormone (ADH), is known as arginine vasopressin (AVP) in the human body. ADH helps the kidneys to retain water. Even though the posterior pituitary has two main hormones they are still very important throughout the body.

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On each side of the kidneys are the adrenal glands. The adrenal gland is broken down into two parts. The adrenal cortex stimulates hormones that help energy and mineral balance. Catecholamine hormones, secreted by the adrenal medulla, aid in the sympathetic nervous system. The "fight or flight" reaction is controlled by the sympathetic nervous system. The main job of the adrenal cortex is to secrete hormones called corticosteriods, which are then broken down into three categories. Mineralocorticoids, glucocorticoids, and sex steriods are the three types of functions by the corticosteriods. The adrenal medulla is in control of secreting hormones epinephrine, and norepinephrine, which are stimulated by the sympathetic nervous system. An example of a "fight or flight" situation would be if you are walking down the street and a man steps in front of you with a knife, demanding money. Do you "fight" the man to not give him your money; or "flight" and run away. The release of hormones from the adrenal medulla would increase the heart rate, increase breathing rate, maybe start perspiration, etc.

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The thyriod gland is located just below the larynx, and the parathyroids are located on the thyroid gland itself. These two glands help control growth throughout the body and the level of calcium in the blood. The thyroid gland has two main hormones, thyroxine (T4) and triiodothyronine (T3). The main function of T4 and T3 is for growth rate and the basal metabolic rate (BMR). The parathyroid glands secrete only one hormone, parathyroid hormone (PTH), helps keep the level of calcium in the blood at a constant rate. Calcitonin and PTH work together to help regulate the blood calcuim level. The thyroid is really important because it controls growth. If the thyroid is not working correctly hypothyroidism or hyperthyroidism may occur. Hypothyroidism is when the thyroid isn't producing enough and hyperthyroidism occurs when the thyroid is over-working. The thyroid needs to maintain a constant state in order for the body to keep homeostasis.

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The pancreas contains specific cells called the islets of Langerhans which are part of the endocrine system. Alpha cells control the hormone glucagon and the beta cells control the hormone insulin. The amounts of glucose must be kept at certain levels in order for the body to be kept at equilibrium. When the glucose levels get too high, the beta cells secrete insulin to lower the levels of glucose. If the level of glucose gets too low, the alpha cells secrete glucagon so the cells have enough energy to keep up their job. The islets of Langerhans are very important to keep the body going at the right healthy rate.

Another important gland is the pineal gland located in the middle of the brain. This gland is very small but still controls the entire body. Melatonin is the main hormonal secretion done by the pineal gland. Inside the hypthalamus, the suprachiasmatic nucleus (SCN), controls the pineal gland and its secretions of melatonin. Each day we wake up and the sun is shining, or going to shine soon, and when the sun goes down, it's time to go to sleep soon. Every 24 hours creates a pattern for our bodies, and that pattern is called the circadian rhythm. During the day when the sun is shining, the dose of melatonin is decreased, and at night the rate of melatonin is increased. Staying up at night or sleeping all day can alter the physiological processes. It's important that we stay awake during the day and sleep during night so the body works at a normal rate.

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Another kind of regulatory molecules are autocrine regulators and paracrine regulators. Autocrine regulators work in the same place they are produced, and paracrine regulators are produced in one place and control another place. Prostaglandins are the biggest and most different group of autocrine regulators. Being produced in almost every organ of the body and producing many different actions, they can be somewhat complicated. Prostaglandins are composed of twenty-carbon-long fatty acids. Throughout most of the systems in the body, prostaglandins aid in their function.

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Every human being has an endocrine system. My future patients' bodies are being controlled by this system. One common disorder of the endocrine system is hyperthyroidism. If I was treating a patient who had recent weight loss, weakness, or nervousness, I should be able to put those symptoms with the disorder of hyperthyroidism. On a personal note, my Mother has hypothyroidism, where the thyroid isn't putting out enough product. She has to take medication to keep up with the levels of hormones in the body. I should become aware of the symptoms of hypothyroidism in case I see them in myself someday. Understanding why something is happening in your own body helps answer questions you may have about your health. Usually when there is an illness or a disorder, patients are going to ask why this is happening. I need to be able to answer that question as a nurse. Being understanding, knowledgable, and caring are all characteristics of a good nurse.

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The pituitary gland is located below the hypothalamus. There are two parts to the pituitary gland, posterior and anterior. The infundibulum is where substances and horomones come from the hypothalamus to the pituitary gland. The anterior pituitary gland produces its own hormones, and it is controlled by the hypothalamus. The posterior pituitary gland does not produce its own hormones, but it does store chemicals from the hypothalamus. One example of a hormone produced by the anterior pituitary is the follicle-stimulating hormone (FSH) that helps in the production of sperm cells and the growth of the ovarian follicles. The sperm cells are made in the testes of the males. In females, the FSH helps in the production of eggs and the menstrual cycle. In males, the FSH usually remains at a constant rate. In females, the levels vary throughout each month. One example of a hormone the posterior pituitary receives is oxytocin. Oxytocin helps women during labor by increasing the uterine contractions and after birth, it helps in the milk production. In men, oxytocin levels rise during ejaculation. Trophic hormones are secreted from the anterior pituitary. They help by regulating the secretion of other hormones by other endocrine glands. Trophic hormones have the ability to turn on or activate the endocrine gland to start secreting its own hormones. Their importance is great, because the anterior pituitary gland controls a large abundance of the body. Trophic hormones need to happen in order for other glands to complete their responsibility too.

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