Endocrine System The endocrine system is a collectionofspecialized body tissues and organs that produce, store, and secrete chemical substances that transfer information and instructions from one set of cells to another. These chemical substance called hormones are secreted to the blood where it is transported to the rest of the body and absorbed by target tissues. These three, chemical signals, receptors and glands comprises the endocrine system.I. Functions:

1. Regulation of bodys activities (reproduction, growth and development, body to achieve homeostasis (state of equilibrium).

2. The endocrine system regulates the growth of tissues, as well as its rate of metabolism. Metabolism is the way by which chemical reactions by which the cells of an organism transform energy, maintain their identity, and reproduce.

3. The endocrine system influences the maturation of tissues, which causes the development of adult features and behavior.4. Blood components control

a. Water balance through maintaining a balanced solute concentration.

b. Ion regulation for it regulates Na+, K+, and Ca2+ concentrations in the blood.

c. Blood glucose control is also performed by the system as well as other nutrients in the blood.

5. The system controls as well the development and functions of the reproductive system, as well as uterine contractions during the delivery of newborns and milk release from lactating females.

6. The endocrine system helps regulate as well the heart rate and blood pressure.

7. The endocrine system plays a crucial role as well in helps control the production and functions of immune cells.

II. Three Key Areas

A. Chemical signals

Hormones chemical signals secreted by cells into the extracellular fluids and regulate metabolic activity of other cells. From its etymology itself to arouse, it brings about changes in other cells by increasing or decreasing the rate of a normal or usual metabolic process. Typically, one or more of the following occurs:

a. changes in plasma membrane permeability or electrical state

b. synthesis of proteins or enzymes

c. activation or inactivation of enzymes

d. stimulation of mitosis

Hormones of the endocrine system reaches nearly every living cell, have specific targets ,whcich means that each kind acts only on certain cell and are called target cells and its control tend to be slower than that of the nervous system. Hormones can either be:

a. Proteins/non-steroid

Proteins, peptides, and amino acid derivatives, hormones in this category are lipid insoluble thus, bind to membrane bound receptors on the

2 cells surface, and their binding either opens or closes cell membrane ion channels or activates enzymes within the cell

b. Lipids/steroids

Steroid hormones, all of which are derived from cholesterol, are lipid soluble and can enter the cells called intercellular chemical signals. (better illustration for both kinds in the next part).

B. Receptors

1. Membrane Bound Receptors extend through the cell membrane, with their receptor sites on the outer surface of the cell membrane. When chemical signals bind to these receptors, the part of the receptor that is inside the cell produces a response. There are three major mechanisms by which they do this:

a. Receptors that directly alter membrane permeability. In this case, once chemical signals bind to the receptor sites, ion channels open or close. That change in membrane permeability alters the movements of ions across the cell membrane, which is responsible for the response.

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b. Receptors and G proteins. This time, when chemical signals bind o the receptor, the result is the activation of the complex of G protein, which has alpha (), beta() and gamma() as subunits bound together. Guanosine Diphosphate (GDP) is bound to the alpha() subunit. Once this happens, the alpha subunit separates from the beta and gamma, and from GDP, Guanosine Triphospate is now bounded to it, and this GTP can either open or close membrane channels, activate enzymes that produce intracellular chemical signals or affect gene expression.

c. Receptors that directly alter the activity of enzymes. This happens in here ways: From the heading itself, inactive enzymes are directly affected and become active once these messages bind.

Moreover, when these chemical messages bind, they activate the enzyme guanylate cyclase which converts GTP to cyclic GMP (cGMP) plus two inorganic phosphate groups (PPi). this activated enzyme then alters other intracellular enzymes to produce a response. Lastly, once these messages bind, they may turn inactive or unphospholyrated sites to phosphorylated ones which produce a response inside the cell.

42. Intracellular Receptors are where small and lipid soluble messages bind to, once they enter the cells, they may be enzymes or even the DNA, which is the ultimate goal. Anyhow, once the chemical messages enter, they make their way to the nucleus to bind to a specific receptor protein in there. It then binds to specific areas on the DNA activating certain genes to transcribe messenger RNA (mRNA). The mRNA then is transmitted to the cytoplasm for the production of new proteins. Comparing the two processes, those chemical messages that bin to membrane bound receptors produce rapid responses. This is because a few intercellular chemical signal molecules can bind to their receptors and each activated receptor can produce many intracellular messages. These in turn, rapidly activate many enzymes inside the cell. What happens is called a cascade effect. On the other hand, it takes several hours for the new synthesis of mRNA and proteins to finish.

3. Hormone Secretion RegulationIn maintaining homeostasis inside the body, it is important that hormones and blood levels of compounds are just around the perfect amount, and the endocrine system does this through the negative feedback mechanism. In here, controlled variables (blood sugar, calcium etc.) and changes in its normal values are corrected by glands by secreting more or less of that hormone. Such negative feedback loop is a stable, self-adjusting mechanism for maintaining homeostasis of the controlled variable.

Another way is through hormone secretion itself. This way, specific hormones are released to trigger the secretion of another (eg. pituitary to ovary/testes). Lastly, some hormone secretion is controlled by the nervous system (eg. epinephrine released from adrenal medulla which is triggered by the nervous system stimulation.

5III. Endocrine Glands and their HormonesPancreas

Pancreas is a mixed glandular organ that is located close to the stomach in the abdominal cavity. As a mixed gland, the pancreas has exocrine function which act as part of the digestive system that produces digestive enzymes, and the endocrine function which produces and secretes hormones. Additionally, the regions of the pancreas that contain its endocrine cells are called pancreatic islets, formerly called islets of Langerhans. The islets are a compact collection of endocrine cells arranged in clusters and cords and are crisscrossed by a dense network of capillaries. The capillaries of the islets are lined by layers ofendocrinecells in direct contact with vessels, and most endocrine cells are in direct contact withblood vessels, by eithercytoplasmic processes or by direct apposition.

Glucagon and insulin are the two important hormones produced by the Alpha and Beta cells, respectively in the pancreatic islets. The glucagon increases the breakdown of glycogen (a moleculethat functions as the secondary long-termenergy storageinanimalandfungalcells) and release of glucose into the cardiovascular system which in effect, raises blood sugar. On the other hand, the insulin increases uptake and use of glucose and amino acids which in effect, lowers blood sugar.

Because of these two hormones, the body maintains normal range of values of blood sugar levels. A decline in the blood glucose level below its normal range causes the nervous system to malfunction because glucose is the nervous systems main source of energy. Furthermore, if blood glucose levels are too high, the kidneys produce large volumes of urine containing substantial amounts of glucose. Dehydration can result because of the rapid loss of water in the body.

Adrenal Gland

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Adrenal glands, which are also called suprarenal glands, are small, triangular glands located on top of both kidneys. An adrenal gland is made of two parts: the outer region is called the adrenal cortex and the inner region is called the adrenal medulla.

Both parts of the adrenal glands: the adrenal cortex and the adrenal medulla perform very separate functions.

The adrenal cortex, the outer portion of the adrenal gland, secretes hormones that have an effect on the body's metabolism, on chemicals in the blood, and on certain body characteristics. The adrenal cortex secretes corticosteroids and other hormones directly into the bloodstream. The hormones produced by the adrenal cortex include:

Mineralocorticoids (aldosterone) targets the kidneys primarily and the intestine and sweat glands to a lesser degree. It increases the rate of sodium transport into the body; increases the rate of potassium excretion and secondarily favor water retention.

Glucocoricoids (cortisol) targets most tissues. It increases the fat and protein breakdown, the glucose synthesis from amino acids, blood nutrient levels, inhibits inflammation and immune response.

Adrenal androgens also target most tissues. It is insignificant in male. But in females, it increases their sexual drive, pubic hair and axillary hair growth.

The adrenal medulla, the inner part of the adrenal gland helps a person in coping with physical and emotional stress. The adrenal medulla secretes the following hormones:

epinephrine(also called adrenaline) -this hormone increases the heart rate and force of heart contractions, facilitates blood flow to the muscles and brain, causes relaxation of smooth muscles, helps with conversion of glycogen to glucose in the liver, and other activities.

norepinephrine (also called noradrenaline) -this hormone has little effect on smooth muscle, metabolic processes, and cardiac output, increasing blood pressure.

The adrenal glands work interactively with the hypothalamus and pituitary gland in the following process: the hypothalamus produces corticotropin-releasing hormones, which stimulate the pituitary gland and the pituitary gland, in turn, produces corticotropin hormones, which stimulate the adrenal glands to produce corticosteroid hormones.

Thymus Gland

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Thymus gland is located between the lungs, behind the breastbone and near the heart. Sometimes it is considered part of the lymphatic system.

The thymus gland produces thymosin and thymopoietin which targets the lymphocytes which are white blood cells that travel the body through the bloodstream. It helps lymphocytes mature, especially in children. The main function of the thymus gland is in the processing and maturation of special lymphocytes called T-cells.

The thymus gland is most active during early life, playing a critical role in the development of a child's immune system before birth and for a time thereafter. Usually by the age of two, the thymus gland has reached its maximum size (weighing about 30 to 40 grams or 1.06 to 1.41 ounces) with the immune system becoming fully functional. Because of this, vaccinations before the age of two are not really necessary since these young immune systems are not mature enough to handle the strength of a vaccine.

If thethymusglandis removed in infancy, theimmune systemwill never fully develop. There is a great degree of infection risk in patients who have nothymusgland, or whosethymusnever developed properly. The majority of lymphocyte production happens early in life, so thethymusglanddeteriorates with age. In youth, thethymuswill reach the size of an apple, but it is reduced to the size of a small marble in the elderly. By the time a person reaches senior citizen status, it is likely their thymusis barely discernible from surrounding fatty tissues. After puberty, the gland begins to shrink and is replaced by connective tissue and fat.

Parathyroid Gland

The parathyroid glands are tiny masses of glandular tissue most often found on the position on the posterior surface of the thyroid gland which produces parathyroid hormone (PTH). The parathyroid hormone targets the tissues of the bone of kidney wherein it increases the rate of bone breakdown by osteoclasts (a type ofbone cellthat removesbone tissueby removing its mineralized matrix and breaking up the organic bone) and PTH also increases vitamin D synthesis that is essential for maintenance of normal blood calcium levels. When blood calcium levels drop below a certain point, thecalcium-sensing receptorsin the parathyroid gland are activated to release hormone into the blood. Parathyroid also controls how much calcium is in the bones, and therefore, how strong and dense the bones are.However, thethyroidgland regulates the bodys metabolism and has no effect on calcium levels while parathyroid glands regulate calcium levels and have no effect on metabolism. When the calcium in our blood goes too low, the parathyroid glands makemorePTH. Increased PTH causes the body to put more calcium into the blood. Increased PTH causes the bones to release their calcium into the blood.Parathyroid hormone (PTH) has a very powerful influence on the cells of the bones which causes them to release their calcium into the bloodstream.When bones are exposed to high levels of parathyroid hormone for several years they become brittle and muchmore prone to fractures.If blood calcium levels fall too law, neurons become extremely irritable and overactive.Pineal Gland

The pineal gland is a small cone shaped gland found on the roof of the third ventricle, near the center of the brain.

It is known to produce a derivative of the serotonin hormone, melatonin. Levels of melatonin fluctuate during the course of a day. This hormone plays a role in the bodys circadian rhythm. This rhythm regulates the physiological functions that occur in the body within a 24-hour period, such as sleep-wake cycles, fluctuations in body temperature, heart rate, and blood pressure.

According to studies, melatonin is believed to be a sleep trigger, making it crucial for the human bodys internal clock for the day and night cycle. Also, it coordinates the hormones of fertility and inhibits the reproductive system, so that sexual maturation is prevented from occurring before adulthood.

Thyroid gland

An endocrine gland found in the neck area, near the parathyroid, that controls metabolism and helps regulate the calcium balance of the body.

The two main hormones it produces are: Thyroxine and Calcitonin. Thyroxine is used in keeping the metabolism going, turning food into energy, also it influences physical development. Calcitonin on the on the hand promotes bone growth, stimulating the uptake of calcium absorption by the bones also inhibiting the activity of bone resorption. Another notable hormone is triiodothyronine.

Without the Thyroid, during childhood years, growth and development would be impossible. Bones would not absorb calcium and the food eaten would not be converted into energy used to promote physical development.

Pituitary Gland

A small endocrine gland located below the hypothalamus about the size of a grape. It is considered to be the master gland, secreting eight different hormones and regulates majority of the other endocrine glands. It consists of two lobes, a posterior lobe and an anterior lobe. It is also known as hypophysis.

Anterior Pituitary

The anterior pituitary is responsible for releasing the growth hormone, thus most cells are target cells. It also secretes the Thyroid Stimulating Hormone (TSH) which increases the thyroid hormone secretion. Moreover, it also secretes the Adrenocorticotropic Hormone (ACTH) which increases cortisol increasing skin pigmentation. Melanin also increases through its secretion of the Melanocyte-stimulating Hormone. The Luteinizing Hormone (LH) promotes ovulation and progesterone production in the ovary, and sperm support and testosterone production in males. Lastly, Prolactin is a hormone which stimulates milk production and prolong progesterone secretion following ovulation and during pregnancy in women.

Posterior Pituitary

The Antidiuretic Hormone (ADH) is secreted to increase water absorption in the kidney so less water is excreted through urine. Oxytocin increases uterine contractions and milk let down from mammary glands.

The pituitary gland is considered the master gland. Any disorder would cause problems in the production of sex cells and would trigger a chain reaction leading to a dysfunctional thyroid gland, adrenal gland and organ failure. 10

Ovaries

The ovaries are paired, almond-sized organs located in the abdomen or pelvic cavity. Aside from producing female sex cells (ova, or eggs), it also produce two groups of steroid hormones, estrogens and progesterone.

During puberty, the anterior pituitary starts to release luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These hormones stimulate the ovaries to begin secreting estrogen and progesterone. This results in the rhythmic ovarian cycles in which ova develop and blood levels of ovarian hormones rise and fall.

Estrogen, produced by the Graafian follicle of the ovaries, initiates the development of female secondary sex characteristics primarily growth and maturation of the reproductive organs and the appearance of hair in the pubic and axillary regions and also so such as breast development, widening pelvis, and distribution of body fat. In addition, the estrogens work with progesterone to prepare the uterus to receive a fertilized egg. This results in cyclic changes in the uterine lining, which is called the menstrual cycle. Estrogens also help maintain pregnancy and prepare the breasts to produce milk (lactation). However, the placenta and not the ovaries is the source of the estrogens at this time.

Progesterone quiets the muscles of the uterus during pregnancy so that an implanted embryo will not be aborted and helps prepare breast tissue for lactation. It is produced by another glandular structure of the ovaries, the corpus luteum. The corpus luteum produces both estrogen and progesterone but progesterone, is secreted in larger amounts. Release of LH, FSH, estrogen, and progesterone continues throughout a womans productive years.

Testes

The testes, located in the scrotum, produce androgens, the male sex hormones. The primary androgen produced by males is testosterone. During puberty the anterior pituitary gland begins to release luteinizing hormone (LH), which stimulates the testes to resume testosterone production. Testosterone causes development of the adult male sex characteristics. It promotes the growth and maturation of the reproductive system organs to prepare the young man for reproduction. It also causes the males secondary sex characteristics (growth of facial hair, development of heavy bones and muscles, and deepening of the voice) to appear and stimulates the male sex drive. LH, FSH, and testoseterone continue to maintain the male reproductive system after puberty.OVARIES AND TESTES:

The adrenal glands in both sexes produce a small amount of a testosterone-like androgen called dihydroepiandrosterone (DHEA). DHEA has no demonstrable effect in males because they have an abundance of the more powerful testosterone. In females, DHEA form the adrenal glands is responsible for many of the same actions as testosterone in males, including enhancement of the female puberta growth, the development of axillary (armpit) and pubic hair, and development and maintenance of the female sex drive.

Intestine

Cells in the lining of the stomach and small intestine secrete hormones that stimulate the production of digestive juices from the stomach, pancreas, and liver. These hormones aid the process of digestion by causing secretion or digestive juices when food is present in the digestive system but not at other times. Hormones secreted from the small intestine also help regulate the rate at which food passes from the stomach into the small intestine, so that food enters the small intestine at an optimal rate.

Placenta

A temporary organ formed during pregnancy, produces hormones generally thought of as ovarian hormones (estrogen and progesterone). Placenta is a remarkable organ formed temporarily in the uterus of pregnant women. In addition to its roles as the respiratory, excretory, and nutrition-delivery systems for the fetus, it also produces hormones that help to maintain the pregnancy and pave the way for delivery of the baby.

During very early pregnancy, a hormone called human chronic gonadotropin (hCG) is produced by the developing imbryo and then by the fetal part of the placenta. Similar to LH (luteinizing hormone), hCG stimulates the corpus luteum of the ovary to continue producing estrogen and progesterone so that the lining of the uterus is not sloughed off in menses. In the third month, the placenta assumes the job of producing estrogen and progesterone, and the ovaries become inactive for the rest of the pregnancy. The high estrogen and progesterone blood levels maintain the lining of the uterus (thus, the pregnancy) and prepare the breasts for producing milk. Human placental lactogen (hPL) works cooperatively with estrogen and progesterone in preparing the breasts for lactation, and relaxing another placental hormone causes them to relax and become more flexible, which eases birth passage. The heart and the kidneys all have functions unrelated to the endocrine system. Nevertheless, all of these organs secrete at least one hormone.12

KidneysErythropoietin and renin are secreted by the kidneys. Erythropoietin stimulates the production of red blood cells in bone marrow. Renin ultimately stimulates aldosterone secretion and constricts blood vessels.

Heart

Atrial natriuretic hormone (ANH) is a peptide (nonsteroid) hormone secreted by the atria f the heart that helps regulate blood pressure. When blood pressure rises, ANH increases the rate at which sodium and water are excreted in urine. This decreases blood volume and lowers blood pressure.

Common diseases of the Endocrine System

Because our Endocrine system is one of two primary systems for controlling bodily functions, the other being the Nervous system, any disruption or Homeostatic Imbalance to it can have dramatic and widespread effects on the body. (Note: many disorders of this system are often chronic conditions of too much (Hypersecretion) or too little (Hyposecretion) Hormone, or tumors (benign or malignant) of the endocrine glands; some of them are inherited condition.)

Here are some of its common disorders.

Hypersecretion of the Antidiuretic hormone (ADH) the ADH is a hormone secreted in the Posterior Pituitary gland that targets the kidney in reducing the amount of water thats lost in urine. This condition is called syndrome of inappropriate ADH secretion (SIADH). People who have SIADH retain too much water to be in a state of water balance. This could result in Hyponatremia, an electrolyte disorder, or fluid overload, a condition wherein there is too much fluid in the blood. Some symptoms may include headaches, nausea, and vomiting. Underlying disorders ranging from HIV infection, meningitis and brain injuries to pneumonia or chronic lung conditions can cause SIADH; some drugs that can increase ADH production can also cause the condition.

Treatments for this condition may include:

a) Treating the underlying causes when possible (i.e. treatment of the meningitis, pneumonia etc.)

b) Long term fluid restriction to lower or correct the water imbalance and to increase serum sodium* (because of hyponatremia wherein sodium concentration in theblood serumis lower than normal.)

c) Drugs such as Demeclocycline, Conivaptan, Tolvaptan etc. that are prescribed by physicians.

Diabetes Insipidus this disorder is the opposite of the SIADH because instead of retaining too much water, the condition is characterized by the inability to save water properly which is caused by either the lack of ADH or by lack of the receptors for ADH in kidney cells. The symptoms may include excessive thirst, excretion of large amounts of severely diluted urine, with the lessening of fluid intake having no effect on the latter; signs of dehydration may also appear in some people since the body cannot conserve much of the water that it takes in. Some cases of Diabetes insipidus can be caused by head trauma or brain surgery that disrupts the normal production of ADH. People with this condition must to drink large amount of water in order to keep up with the amount of water lost by their kidneys. 13Pituitary Dwarfism or Growth Hormone Deficiency (GDH) this condition is caused by Hyposecretion of the growth hormone during childhood. The Growth Hormone (GH), from the Anterior Pituitary gland, is importantly involved in the growth and development process of children therefore abnormalities of growth hormone secretion are most damaging when they happen before puberty. It is characterized by having poor growth and/or shortness, and having cherubic facial feature or that which resembles a kewpie doll. In order to correct this disorder, it should be diagnosed early and treated with growth hormone throughout childhood; otherwise, if the patient reaches adulthood, even administering the growth hormone cannot overcome the disorder. This is because during puberty, the sex steroid hormones causes the cartilaginous growth plates at the ends of long bones to be replaced by bone so after that, bones do not grow in length again.

Gigantism this disorder is caused by hypersecretion or overproduction of the growth hormone during childhood and adolescence. Excess GH secretion can come from hormone-secreting tumors on the pituitary gland. Exaggerated bone growth occurs when excess GH is present before bones complete their growth in length, this results in the person being abnormally tall. There is no known cure for gigantism and many of those identified with it have suffered multiple health problems regarding their circulatory and skeletal system.

Acromegaly this disorder is similar to gigantism except it does not make the individuals whole body grow abnormally taller, rather it only makes some parts of the body grow to abnormal proportions. This is because if the excess hormone is secreted after growth in bone length is complete, the bone growth continues in diameter, but not in length (the reason why this disorder is only common in adults or those reaching adulthood); as a result, the bones and muscles of the face, hands, and feet (the bones that arent affected by sex steroids) become abnormally large, changing patients facial features but not their height. The excessive production of GH in adults usually comes from tumors of the pituitary or hypothalamus. Nowadays however, this disorder is no longer common since the GH-secreting tumors are now usually being diagnosed and treated early enough that the condition never develops.

Diabetes mellitus commonly known as Diabetes, this condition is a disorder of blood sugar regulation involving insulin (a hormone thats produced in the pancreas, it is important in regulating carbohydrate and fat metabolism in the body, and causes cells in the liver, muscle, andfat tissuesto take upglucosefrom theblood, storing it asglycogenin the liver and muscle.). There are two types of diabetes:

a) Type 1 diabetes this is caused by a failure to produce enough insulin, because of this, the patient only depends on daily doses of insulin for survival, which is why it is also called insulin-dependent diabetes. It normally develops during childhood or adolescence, but adults can develop it as well. Generally it has an autoimmune (failure of an organism to recognize a constituent as part of itself, therefore causes immune responses against its own cells and tissues) cause: the persons immune system destroys the beta cells (cells that make and release insulin) of the pancreas.

b) Type 2 diabetes also referred to as non-insulin-dependent diabetes, unlike Type 1, insulin levels may be low, normal or quite high, however, it is characterized by insulin resistance which means cells fail to respond adequately to insulin even though it is present.

Both types of Diabetes mellitus can damage the blood vessels and nerves if not managed correctly. Chronic untreated diabetes is a leading cause of blindness, kidney failure, heart disease and stroke. People who are overweight and sedentary (no or irregular physical activity) are more prone to develop this disease, specifically Type 2 diabetes. The symptoms of having Diabetes are: polyuria(frequent urination),polydipsia(increased thirst) andpolyphagia(increased hunger), which may develop rapidly (weeks or months) in Type 1 while in Type 2 they usually develop much slower and may be subtle or absent. In addition, Type 2 diabetics may experience having frequent infections, blurred vision, cuts that heal very slow, and tingling in the feet or hands. To manage their condition, Type 1 diabetics need daily injections of insulin to stay alive, while Type 2 diabetics have numerous options depending on their condition. Some may take insulin, but others manage with drugs that stimulate insulin production. Others can be managed without drugs through lifestyle changes like maintaining a healthy weight, eating nutritious food, and regular, if not daily exercising.

Goiter this disorder is of the Thyroid gland wherein the lack of iodine, (which is required to produce active Thyroid hormones) which results in an absent or abnormally low level of thyroxine, makes the hypothalamus and pituitary to secrete large unchecked quantities of Thyrotropin-releasing hormone (TRH) and Thyroid-secreting hormone (TSH). And in doing so, the high TSH levels stimulate the thyroid gland to grow to enormous size in an effort to get the thyroid to make more hormone, which it cannot do because it lacks iodine. As a result, the thyroid gland is abnormally enlarged and causes a swelling of the neck or larynx (voice-box) which we call a Goiter.

Note: the TRH is a hormone that stimulates the release of TSH by the anterior pituitary. TSH on the other hand is a hormone which is also secreted in the anterior pituitary gland but regulates the endocrine function of the Thyroid gland. Thyroxene is the hormone secreted by the thyroid gland.

Hypothyroidism: Underactive thyroid gland this refers to the hyposecretion of thyroid hormones. In children, not enough thyroxene production can slow body growth, alter brain development, and delay the start of puberty. If not treated, the hypothyroidism can lead to cretinism, a condition of mental retardation wherein the child is left with short stature with an abnormally formed skeletal structure. In adults, thyroxene deficiency can lead to myxedema, a condition characterized by swelling under the skin, lethargy (Fatigue), weight gain, low BMR (Basal-metabolic rate refers to the amount of energy expended while at rest), and low body temperature. This condition however, can be treated by means of thyroxine pills which can increase thyroxene production.

Hyperthyroidism: Overactive thyroid gland this refers to the hypersecretion of the thyroid hormones. Too much thyroxine increases BMR and causes hyperactivity, nervousness, agitation, and weight loss. Graves disease, an autoimmune disorder wherein the persons own aintbodies stimulate the thyroid to produce too much thyroxine, is the most common form of hyperthyroidism. Graves disease is often associated by protruding eyes, a condition called exopthalmia, caused by fluid accumulation behind the eyes.

Addisons disease: Too little cortisol and aldosterone this condition is caused by the failure of the adrenal cortex to secrete sufficient cortisol (a steroid hormone used in increasing blood sugar) and aldosterone (a hormone that increases blood volume, therefore, increasing blood pressure). The disease tends to develop slowly with chronic symptoms of fatigue, weakness, abdominal pain, weight loss, and characteristic bronzed skin color. It can be successfully treated by replacing the missing hormones.

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Cushings syndrome: Too much cortisol too much cortisol may result in excessive production of glucose from glycogen and protein, and retention of too much salt and water. Some of the extra glucose is converted body fat, but only in certain areas of the body like the face, abdomen, and the back of the neck.

Some symptoms include muscle weakness and fatigue, edema (swelling due to too much fluid), and high blood pressure. It can be caused by tumors of the adrenal gland or Adrenocorticotropic hormone(ACTH a hormone produced in the anterior pituitary gland that increases production and release of corticosteroids and cortisol from the adrenal cortex)-secreting cells of the pituitary. It can also be due to excessive use of cortisol or cortisol-like drugs (cortisone, prednisone, dexamethasone, and others) to control chronic inflammatory conditions such as allergies and arthritis. Most Cushing's syndrome cases are caused by steroid medications, consequently, most patients are effectively treated by carefully tapering off (and eventually stopping) the medication that causes the symptoms.Bibliography

(n.d.). Retrieved 02 04, 2011, from http://www.restorativemedicine.com/books/fundamentals-of-naturopathic-endocrinology/professionals/clinical-handbook-diagnostic-therapeutic-protocols/pineal-gland-disorders

(n.d.). Retrieved 02 04, 2011, from www.wayfinding.net: http://www.wayfinding.net/pineal.htm

Johnson, M. (2006). Endocrine System. In M. Johnson, Human Biology, 3rd Edition (pp. 290-309). San Francisco, California: Pearson Benjamin Cummings.

Premium, M. E. (2009). Microsof Encarta Premium DVD 2009. Endocrine System.

Seeley, R., Stephens, T., & Tate, P. (2007). Endocrine System. In R. Seeley, T. Stephens, & P. Tate, Essentials of Anatomy and Physilogy 6th Edition (pp. 266-269). New York: Mc Grw Hill Companies Inc.

www.cartage.org. (n.d.). Retrieved 02 09, 2011, from http://www.cartage.org.lb/en/themes/sciences/lifescience/generalbiology/physiology/endocrinesystem/Hormones/Hormones.htm

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