For something to share, I remembered asking a friend, why a girl I am acquainted with, happens to be slimmer than me where in fact she eats more than what I do, My friend’s response was " Maybe it is because of her metabolism". At that time, in my mind, I am pondering what could have caused her metabolism to be that way?

Bearing in mind studies in Anatomy, it is stated that there are several processes occurring inside an organism. One of these processes important for humans consist of metabolism, given that human beings are complex organisms and are multicellular, the cells that assembles the human body needs nourishment in order to function suitably, and the food we get undergo metabolism so as to attain the nutrients that will nurture this cells. Reproduction on the other hand is also an essential process in sustaining life; nevertheless this could only ensue if our reproductive appendages have matured. Reproduction and Metabolism are some of the physiological processes regulated by chemical mediators we identify as hormones, and these mediators are the specialization of the field of Endocrinology.

Fig. 1 - The Different Glands of the Endocrine system
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Based on Etymology, Endocrine, if the name is dissected, came from the Greek words , endo or “within“ and crinis or“to secrete” putting all of this together, it could be conceived that the Endocrine system encompasses secretions happening within or inside our bodies, such secretions, called hormones are exuded by the glands which are some of the components of the aforementioned system. Supplementing another Greek word, logos, which meant to study, we could come up with the word Endocrinology. Endocrinology then, to sum it up, connotes the study of the Endocrine system.

Endocrinology focuses on the study of the chemical substances called Hormones (Chemical Mediators), this hormones standardize Growth and development, Metabolism, Reproduction and other tissue purposes, having said that, Hormones could be accountable for your built or physique due to their directive of food metabolism, like for instance a person with fast metabolism could be a lot emaciated compared to a person with slow or normal rate of metabolism despite the condition that they eat the same amount of food, just like my experience. A person with problems with their Growth Hormone could have stunted development or other diseases compared to those with normal hormones, this are some cases focused on this science, therefore Endocrinology is considered a branch of internal medicine which deals with“hormonal” problems.

Endocrinology, in addition, has something to do with case of sexuality and reproduction. The Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH), Estrogen and Testorone, are quite a few of this chemical mediators which motivates development of the secondary sexual characteristics of the male and female, on the other hand, the hormones Prolactin and Oxytocin are both noteworthy in child-bearing.

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Endocrinology as a division of medicine, also focuses on diseases taking place from the Endocrine system, such pathologies includes abnormalities in the hormones or other metabolic diseases such as Diabetes Mellitus, a lifestyle disease caused by the deficiency or malfunction of the hormone, Insulin, which regulates blood sugar. It converges on problems caused by "hormonal imbalance" which are either rooted by Hypersecretion or hyposecretion of the hormones. Diabetes, Thyroid Disorders, Bone Disorders, Reproduction/Infertility, Obesity, Pituitary Gland disorders and Growth Disorders are some of the ailments Endocrinologists works on to elucidate.

Fig. 2- The Locations of Endocrine Glands
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Table 1 – Summary of The Endocrine system

 

Endocrine Gland	Hormone(s) Secreted	Function(s) of Hormones
(1) Hypothalamus	Part of the Brain: The Control and Relay Centre of the Endocrine System.
(2) Pituitary	Known as the "Master Gland", this part of the brain consists of three lobes called "anterior", "interior" and "posterior".
Posterior	Oxytocin	Stimulate utrine contraction and brest contraction for milk release.
Posterior	Anti-Diuretic Hormone (ADH), also known as "vasopressin"	Stimulates re-absorption of water from kidney tubules. Hypo- causes Diabetes Insipidus (large amounts of urine produced).
Anterior	Prolactin (PRL)	Production of breast milk (works in men too).
Anterior	Human Growth Hormone (HGH)	Growth Hypo- Dwarfism Hyper- Gigantism
	Thyroid Stimulating Hormone (TSH)	Stimulates the thyroid to release thyroxin.
Anterior	Adrenocorticotrophic Hormone (ACTH)	Stimulates the adrenal cortex to produce: Corticosteriods: mineral corticoids glucocorticoids cortisol (natural anti-inflammatory) androgens, e.g. acdosterone
Anterior	Luteinizing Hormone (LH)	Brings about ovulation and maintains the corpus luteum.
Anterior	Follicle Stimulating Hormone (FSH)	Stimulates growth/development of Graafin follicles (= a mature follicle in the ovary prior to ovulation, containing a large fluid-filled cavity that distends the surface of the ovary) on approx. 28 day cycle.
	Gonadotrophins	Secondary sexual characteristics
Anterior	Interstitial Cell Stimulating Hormone (ICSH)	Works on the seminiferous tubules in the testes – to produce sperm – which take 21 days to mature. (If not ejaculated within 21 days, the sperm are re-absorbed back into the body.)
Intermediate	Intermedin	Control of melanocyte production.
(2) Pineal	A pea-sized mass of nerve tissue attached by a stalk to the posterior wall of the third ventricle of the brain, deep between the cerebral hemispheres at the back of the skull. (It functions as a gland, secreting the hormone melatonin - which regulates the pituitary gland and is associated with the biological clock.)
	Melatonin	A hormone produced by the pineal gland in darkness but not in bright light. Melatonin receptors in the brain react to this hormone and synchronize the body to the 24 hour day/night rhythm, thus informing the brain when it is day and when it is night. Melatonin is derived from seratonin, with which it works to regulate the sleep cycle.
(3a) Thyroid Gland	Part of the Thyroid/Parathyroid Gland, which is in the neck
	Thyroxin	Concerned with the Basal Metabolic Rate (BMR), which is the amount of energy the body uses, just to ‘tick over’ Hyper-Thyroidism = ‘over-active thyroid’ = Thyrotoxicosis Symptoms: increase in BMR; increase in heart-rate; loss of weight; hyper-activity; insomniac; develops bulging eyes due to accumulation of fluid behind the eye; may develop Goitre; possible link with Attention Deficit Disorder. Hypo-Thyroidism Symptoms; decrease in BMR; weight gain; lethargy; skin becomes dry and puffy; hair becomes thin and brittle. Causes: Derbyshire Neck (originally due to insufficient iodine in the soil in Derbyshire), Graves Disease, and Cretinism (= metal and sexual development imapaired, if occurs in children).
	Calcitonin	Uptake of calcium to bone.
(3b) Parathyroid Gland	Part of the Thyroid/Parathyroid Gland, which is in the neck.
	Parathormone	Associated with the growth of muscle and bone. Distribution of calcium and phosphate in the body. Hyper- Causes transfer of calcium from the bones to the blood; bones become fragile & easily broken; osteoporosis. (Parathormone activity is inhibited by oestrogen.) Hypo- Lowers blood calcium levels, causing tetany (which may be treated by injections of the hormone); low calcium levels in skeletal muscle (which may cause cramps).<><><>
(4) Thymus	The thymus gland is located straddled across the trachea & bronchi in the upper thorax (a bi-lobed organ in the root of the neck, above and in front of the heart). The thymus (a gland associated with the immune system), is enclosed in a capsule and divided internally by cross-walls into many lobules (full of T-lymphocytes). In relation to body size the thymus is largest at birth. It doubles in size by puberty, after which it gradually shrinks, its functional tissue being replaced by fatty tissue. In infancy the thymus controls the development of lymphoid tissue and the immune response to microbes and foreign proteins (accounting for allergic response, antoimmunity, and the rejection of organ transplants). T-lymphocytes migrate from the bone marrow to the thymus, where they mature and differentiate until activated by antigen.
	Thymosin	Activates the immune system by activating the T-Cells (T-Killer Cells; T-Helper Cells; T-Memory Cells). <><><> <><><><><>
	T-Lymphocytes	The thymus consists of lobules full of T-lymphocytes (white blood cells associated with antibody production). T-lymphocytes migrate from the bone marrow to the thymus, where they mature and differentiate until activated by antigens. <><><> <><><><><>
(5) Pancreas	The pancreas lies behind the stomach. It is both exocrine (ducted) and endocrine (ductless). As an exocrine gland it secrets enzymes (organic catalysts) into the small intestine: The enzymes are: Pancreatic amylase (which breaks down polysaccharides, i.e. starch into sugar) Lipase (which breaks down fats into fatty acids and glycerol) Proteases (which breaks down protein (polypeptide) into di-peptides). <><><> The islets of Langerhans are within the pancreas.
Islets of Langerhans	Located within the pancreas. Contains groups of both Alpha- and Beta- cells.
Beta Cells	Insulin	Conversion of glucose to glycogen. Cellular up-take of Glucose. Conversion of excess glucose to fat. Hyper- Hypo- causes Diabetes Mellitus: Symptoms: Blood glucose levels rise (hyperglycaemia). Glucose is excreted into the urine (glycosuria) - which increases levels of urination, causing dehydration. As glucose levels in the blood increase, fa and protein are broken-down for energy. Coma and death may follow if the symptoms are not treated.
Alpha Cells	Glucagon	Conversion of glycogen to glucose.
(6) Adrenal Glands
Adrenal Medulla	Adrenalin	Prepares the body for "fright, fight or flight" and has many effects: Action of heart increased. Rate and depth of breathing increased. Metabolic rate increased. Force of muscular contraction improves. Onset of muscular fatigue delayed. Blood supply to the bladder and intestines reduced, their muscular walls relax, the sphincters contract.
	Noradrenalin	Similar effects to adrenalin: Constriction of small blood vessels leading to increase in blood pressure. Increased blood flow through the coronary arteries and slowing of heart rate. Increase in rate and depth of breathing. Relaxation of the smooth muscle in the intestinal walls.
Adrenal Cortex	Corticosteroids	Glucocorticoids (e.g. cortisol, cortisone, corticosterone) Utilization of carbohydrate, fat and protein by the body. Normal response to stress. Anti-inflammatory effects. Hypersecretion of cortisol results in Cushings Syndrome. Mineralocorticoids (e.g. aldosterone) Regulation of salt and water balance. Hypersecretion of Alderosterone decreases the potassium in the body (affecting nerve impulse transmission and leading to muscular paralysis).
(7) Ovaries	Produce mature ova. Theoretical potential for 400-450 viable ova. (Therefore the more and the longer pregnancies a woman has, the later her menopause because there is no ovulation during pregnancy.)
	Oestrogen	Break-down of the utrine wall.
	Progesterone	Builds up and maintains the uterus wall for embedding of fertilized egg. Associated with secondary sexual characteristics, e.g. body hair, breast enlargement, changes in physical body.
(8) Testes	Located outside the pelvic cavity.
	Testosterone	Development and function of male sex organs. Secondary sexual characteristics. e.g. body hair, muscle development, voice change.

Table Data Source: http://www.ivy-rose.co.uk/HumanBody/Endocrine/Endocrine_Glands.php

Tests carried out on endocrinology, involves measurement of hormones in order to assess certain anomalies, some examinations even entail radioactive substances seeing as these hormones are very intricate. Treatments could either be suppression or stimulation of the hormone production.

To know more about Endocrinology Click on this link. and on the links provided below.

· Becker, J., Behavioral Endocrinology, 2nd Edition, 2002, Massachusetts Institute of Technology

· Becker, K., Principles and Practice of Endocrinology and Metabolism, 3rdEdition, 2001, Lippincott Williams and Wilkins

· Goodman, H.M., Basic Medical Endocrinology, 3rd Edition, 2003, Elsevier Science (USA)

· Turgeon, M.L., clinical Laboratory Science, 5th Edition, 2007, Elsevier Inc. (Singapore)

· http://emedicine.medscape.com/endocrinology

· http://www.hormone.org/Public/endocrinologist.cfm

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