Endocrine Glands and the effects of hormones

24 03 2010

Using a direct translation of the word endocrine, it means to secrete within and though the purposes of each different gland’s hormonal secretion is different, they all work in the same manner, releasing a chemical throughout the body (Barnes).  I found many conflicting resources in researching the endocrine system; some alluding to only seven or eight glands and others up to nine and ten.  Some of the contradictions I found debated the inclusion of the hypothalamus as its own separate gland or that it is part of the pituitary gland, and the hypothalamus as part of the thalamus, which in some sources was not indicated to be a gland at all.  Yet noting that much of the research and knowledge we do have on endocrine glands has been done in my lifetime, it makes sense that there is a good deal of confusion as to their functions and classification.  As this isn’t the period of da Vinci and other medical researchers of generations previous, thus cutting apart human bodies for study is a bit taboo, so they are left to study animals and other species and attempt to draw parallel conclusions.

“The pituitary is essential to normal life,” stated Dr. Fussell in his work, Monographic Medicine (Fussell 515).  And while it is true that the pituitary does appear to control all other glands within the body, the hypothalamus gland instigates the pituitary and would to this researcher appear even more essential.  The pituitary gland visually looks like the aril of a pomegranate, not only in size but also in colour with a bright crimson bulb at the base and the hypothalamus at the crown.  I found it interesting that these are formed during gestation as tissue in the roof of the mouth grows upwards while a tissue in the brain grows downwards and eventually the two tissues merge to form the pituitary gland, complete with attached hypothalamus (Bowen).  The hypothalamus connects the endocrine system to the nervous system, working with neurons in the brain to signal to the pituitary gland the appropriate actions, as discovered by Roger Guillemin and Andrew Schally (Nobel Foundation).  The secretions of the hypothalamus are neurohormones and regulate body temperature, emotions, sexual response, response to stressors, growth of the body and body parts, response to pain through thyrotropin-releasing hormone also known as TRH, gonadotropin-releasing hormone referred to as GnRH, corticotrophin-releasing hormone called CRH and gastrointestinal neuropeptides, respectively (Farr).

From the secretions received from the hypothalamus, the pituitary gland then sets in motion responses from other glands and parts within the body.  For example, upon receiving stimuli related to growth, the pituitary releases a hormone called somatropin, which then travels through the body to tissues and bones and muscles, signaling growth.  When there is an abnormal amount of somatropin released by the pituitary gland gigantism, dwarfism or other growth related disorders can result (Hormones Foundation).  The pituitary gland also secretes melanocyte-stimulating hormone called MSH, thyroid-stimulating hormone known as TSH, adrenocorticotropic hormone referred to as ACTH, endorphin, luteinizing hormone or LH, vasopressin or ADH, and oxytocin (Rose).  MSH has been found to impact the effect of melanin in non-human test subjects, but thus far scientists have been unable to determine its purpose within the human body (Kimball).  TSH is released to signal the thyroid gland into action to release thyroxine and triiodothyronine; ACTH is a signal for the adrenal glands; and LH sets the reproductive glands into motion (NIH).  ADH is released to regulate blood pressure and volume and signals the kidneys to increase the total amount of water within the body (Eckman).  “Oxytocin may be mediating emotional experiences in close relationships,” stated Dr. Rebecca Turner in her research article on the impact of oxytocin in the body, which stimulates contractions during labour, aides in orgasms during sexual intercourse, but also, per Dr. Turner and colleagues, appears to dramatically impact our responses to stress and emotions in relationships (Turner et al).  Endorphins, released also by the pituitary gland, reduce inflammation in the body and stimulate the dilation of the blood vessels, which in turn can reduce plaque formation by cholesterol through their release of nitric oxide (Miller).

This brings us to the thyroid gland which during gestation is located at the back of the tongue, but by birth moves into place, typically, at the front of the throat (Endocrine Web).  The hypothalamus releases TRH, as explained previously, which triggers the pituitary to release TSH, which stimulates the thyroid to create a hormone known as TH (Saul).  TH is composed of triiodothyronine or T3 and thyroxine or T4, which manage our body’s metabolism, directly impacting our heart rate, blood pressure and the activity level of our intestines (Keene).  Behind the thyroid are four segments, which some researchers have comingled with the thyroid gland and yet other sources set them apart as individual glands that are called the parathyroids.  No matter their classification, their function is to secrete a hormone referred to as PTH, parathyroid hormone, and the sole function of this gland is to regulate the level of calcium in our body (Norman).

The thymus is sometimes associated with the lymphatic system, rather than the endocrine system (Britannica), however its sole function is the creation of T-Cells, and thus this researcher selects not to include this in the list of endocrine glands as it has no known hormonal secretion and actually dissipates with age.

That brings us to the adrenal glands, of which the body has two, each located atop the kidneys.  These glands have two sections with separate functions, the cortex and the medulla (Eckman).  The cortex releases steroid hormones – Glucocorticoids, Mineralcorticoids, and Androgens.  Glucocorticoids regulate the functions of carbohydrates in the body with cortisol being the most common of these hormones.  I found it really interesting to learn that glucocorticoids are naturally anti-inflammatory and that medicines used to treat inflammatory disorders instigate the activity of production of glucocorticoids.  Mineralcorticoids prompt for the removal of electrolytes from the body and reabsorb sodium (King).  And androgens include testosterone and are the staple of most performance enhancing steroids as they promote muscle tissue growth (Bioidentical Hormone Therapy).  The medulla releases what are known as Catecholamines, such as epinephrine and norepinephrine, and function to help the body react to stress by increasing the heart rate, dilating the pupils, and interestingly enough – stimulates the body to utilize fat cells for energy (Bowen).  It was interesting to this researcher to put the two and two together, so to speak, of the benefit of exercise on weight loss, as the catecholamines can be triggered to begin working as a result of activity, such as exercise.

This brings us to the gonads, ovaries or testis depending on the sex of the individual (MedicineNet).  I never knew that the ovaries and testicles originated from the same gland during gestation and dependent upon the chromosomes and found that riveting!  As with each other gland, the gonad glands’ secretions begin with the hypothalamus secreting GnRH to the pituitary gland which then releases LH to the gonads.  When the gonad is in a female, the ovaries then secrete the female hormone called estrogen; in males, the secretion is testosterone (Kimball).  Both sexes have both hormones, though there should be a significantly higher level of hormone related to the sex of the individual as opposed to the amount of hormone related to the opposing sex.  Estrogen hormones in women prompt for the development of the sex organs – breasts, vagina and uterus, while also strengthening bones and aiding in the clotting of blood (Kimball).  In males, too much estrogen can lead to large breasts, erectile dysfunction, diabetes, and even put them at risk for certain cancers (BodyLogicMD).  Testosterone in males produces healthy sperm, and facial hair (Kimball), while in women it lowers muscle mass and can increase energy (BodyLogicMD).  I found it interesting that a gland that starts out unisex at conception later becomes so critical in the identity of individuals and that while it emits the same types of hormones; they are in such a perfect balance based on the sex of the person that a slight tip in the balance can have devastating results.

As you can tell, there are various schools of thought on which glands are included in the list of endocrine glands and which are viewed as subsets of a primary gland.  Their functions are wide reaching and are clearly a critical part of human life and function.

Work Cited

Barnes, Broda O. “Endocrine System.” Research Foundation, Inc., 10 Dec. 2007. Web. 17 Mar. 2010. <www.brodabarnes.org/endocrine_sys.htm>.

“Bioidentical Androgens Used to Enhance Performance and Risks Associated.” Androgens. Bioidentical Hormone Therapy. Mon. 22 Mar. 2010. <http://androgens.org/&gt;.

“Estrogen Levels.” BODYLOGICMD. Mon. 22 Mar. 2010. <http://www.bodylogicmd.com/for-men/estrogen-levels&gt;.

Bowen, R. A. “Pathophysiology of the Endocrine System.” Hypertexts for Biomedical Sciences. Colorado State University, 9 July 1997. Web. 17 Mar. 2010. <www.vivo.colostate.edu/hbooks/pathphys/endocrine/>.

“thymus.” Encyclopædia Britannica. 2010. Encyclopædia Britannica Online. Sun. 21 Mar. 2010 <http://www.britannica.com/EBchecked/topic/594569/thymus&gt;.

Eckman, Ari S. “ADH.” MedLine Plus. National Institutes of Health, 14 Oct. 2009. Mon. 22 Mar. 2010. <http://www.nlm.nih.gov/medlineplus/ency/article/003702.htm&gt;.

Eckman, Ari. “Adrenal Glands.” MedLine Plus. National Institutes of Health, 23 Nov. 2009. Sun. 21 Mar. 2010. <http://www.nlm.nih.gov/medlineplus/ency/article/002219.htm&gt;.

“How Your Thyroid Works.” Endocrine Web. Vertical Health, 21 Mar. 2009. Sun. 21 Mar. 2010. <http://www.endocrineweb.com/thyfunction.html&gt;.

Farr, Gary. “The Nervous System.” BecomeHealthyNow. 2 July 2002. Fri. 19 Mar. 2010. <http://www.becomehealthynow.com/article/bodynervousadvanced/956/&gt;.

Fussell, M. Howard. Monographic Medicine. Vol. V. New York and London: D Appleton and Company, 1917. Print.

“Growth Disorders Overview.” The Hormones Foundation. Matrix Group International. Sat. 20 Mar. 2010. <http://www.hormone.org/Growth/overview.cfm&gt;.

Keene, Nancy, and Kevin Oeffinger. “Late Effects to the Thyroid Gland.” Candlelighters Childhood Cancer Foundation. CCCF Newsletter, Spring 2001. Fri. 19 Mar. 2010. <http://www.candlelighters.org/Information/lateeffectsthyroid/tabid/345/Default.aspx&gt;.

Kimball, John W. “Melanocyte-Stimulating Hormone (MSH).” Kimball’s Biology Pages. 7 Nov. 2009. Thurs. 18 Mar. 2010. <http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/M/MSH.html&gt;.

Kimball, John W. “Hormones of the Reproductive System.” Kimball’s Biology Pages. 14 Nov. 2009. Mon. 22 Mar. 2010. <http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/S/SexHormones.html&gt;.

King, Michael W. “Steroid Hormones.” MedicalBiochemistry. 19 Dec. 2009. Mon. 22 Mar. 2010. <http://themedicalbiochemistrypage.org/steroid-hormones.html&gt;.

“Definition of Gonad.” MedicineNet, 1 Apr. 1999. Mon. 22 Mar. 2010. <http://www.medterms.com/script/main/art.asp?articlekey=8980&gt;.

MedLine Plus. National Institutes of Health, 14 Oct. 2009. Mon. 22 Mar. 2010. <http://www.nlm.nih.gov/medlineplus/ency/article/003702.htm&gt;.

Miller, Michael. “Tune Up Your Health.” National Institutes of Health, 29 Jan. 2010. Fri. 19 Mar. 2010. <http://www.nlm.nih.gov/medlineplus/news/fullstory_94715.html&gt;.

“1977 Press Release.” Nobel Prize. Nobel Foundation, Oct. 1977. Fri. 19 Mar. 2010. <http://nobelprize.org/nobel_prizes/medicine/laureates/1977/press.html&gt;.

Norman, James. “Introduction to the Parathyroid Glands.” Norman Parathyroid Center, 11 Aug. 2009. Fri. 19 Mar. 2010. <http://www.parathyroid.com/parathyroid.htm&gt;.

Rieser, Marianne, and Stephen Kemp. “Anatomy of the Endocrine System.” EMedicineHealth. EMedicine.com, Inc., 30 Dec. 2005. Sun. 21 Mar. 2010. <http://www.emedicinehealth.com/anatomy_of_the_endocrine_system/&gt;.

Rose, Norman. “Pituitary Gland.” The Hormone Shop, LLC, 10 Nov. 2009. Fri. 19 Mar. 2010. <http://www.thehormoneshop.com/pituitarygland.htm&gt;.

Saul, Leif. “Endocrine System.” Biology in Motion. http://www.biologyinmotion.com/thyroid/index.html, 2005. Mon. 22 Mar. 2010. <http://www.biologyinmotion.com/thyroid/index.html&gt;.

Swerman, Marshall. “What Does Your Endocrine System Do?” Articles Base. 29 Aug. 2008. Web. 17 Mar. 2010. <www.articlesbase.com/health-articles/what-does-your-endocrine-system-do-541020.html>.

Turner, Rebecca, Teresa McGuinness, Margaret Altemus, Teresa Enos, and Bruce Cooper. “HORMONE INVOLVED IN REPRODUCTION MAY HAVE ROLE IN THE MAINTENANCE OF RELATIONSHIPS.” Psychiatry 65.7 (1999): 97-113. Print.




6 responses

26 06 2010

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14 07 2010

Thank you.

12 07 2010

Can I source your infro?

14 07 2010

Yes, Yodma. Thank you for asking.

20 10 2010

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