The Importance of the Hypothalamus

Why the Hypothalamus has my vote!

Wham BAMM Thank You Gland

Meghan Kurz, Ameara Powell, Becca Fehrenbach, & Maggie Fehrenbach

Why the hypothalamus will implicate the change you want to see in the body!

The hypothalamus conveniently lives in head quarters (brain) just below the thalamus and right above the pituitary gland and brain stem allowing her close communication with some of our most important leaders. Though she be but small (almond size!), she is mighty.

She dedicates her life to maintaining balance and peace throughout the body (homeostasis). By responding to a variety of signals from the internal and external environment she is able to collect and combine information and implement changes to correct any imbalance and regulate bodily functions neccessary to life.

She produces and secretes releasing and inhibition hormones that regulate and govern physiologic functions such as temperature regulation, thirst, hunger, sleep, mood, sex drive, childbirth, milk production, functions of the gonads and ovaries, blood pressure and blood volume, stress, growth, emotions.

The primary function of linking the nervous system to the endocrine system via the pituitary gland is vital in maintenance of the human body.

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Credentials to Consider; The Hormones

Anti-Diueritic Hormone (arginine vasopressin) is synthesized by the hypothalamus and helps to control blood pressure by acting on the kidneys and the blood stream. The most important role is to conserve fluid volume by reducing the amount of water passed out in the urine. Low blood pressure or low volume (hypovolemic shock or dehydration) is detected by special sensory receptors in the hypothalamus, which stimulates ADH release. ADH is also released by thirst, nausea, vomiting, and pain working to keep fluid volume stable in the blood stream during times of stress or injury.


Growth hormone-releasing hormone is produced in the hypothalamus and stimulates the pituitary gland to produce and release the growth hormone into the blood stream. The hypothalamus monitors the amount of GH in the bloodstream and prevents or releases growth hormone-releasing hormone. Growth hormone is a somatotrophic secretory cell which regulates metabolic processes involving growth and adaptation to physical and emotional stressors, muscle growth, increased protein synthesis, increased liver glycogenolysis and increased fat metabolism. The growth hormone is neccessary to aid growth in children for bone and muscle development. As an adult, GH continues releasing to promote maintence of healthy bones and sufficient energy.


Corticotrophin-releasing hormone (CRH) is secreted by the paraventricular nucleus (PVN) of the hypothalamus in response to stress. It follows a 24 hour rhythm in non-stress circumstances. CRH levels are highest at 8am and lowest overnight. The main role in the body is to control the hypothalamic pituitary axis (HPA) which responds to stress in the body. The hypothalamus releases corticotrophin-releasing hormone. In turn this causes the release of the adrenocorticotropic hormone (ACTH) which travels through the bloodstream to cause the adrenal gland to secrete cortisol. Cortisol is a glucocorticoid hormone that will then initiate metabolic changes. Other roles of CRH are to suppress appetite, increase anxiety, improve memory and selective attention, this affects the body's response to stressful experiences.


Thyrotropin-releasing hormone (TRH) is a trophic, tripeptidal hormone which is produced by the hypothalamus. TRH stimulates the release of thyrotropin (thyroid-stimulating hormone or TSH), which stimulates the thyroid gland to produce thyroxine (T4) and then triiodothyronine (T3). T4 and T3 stimulate metabolism of almost every tissue in the body. TRH also controls prolactin secretion. Prolactin is secreted by the pituitary gland in pulsatile fashion in response to eating, mating, estrogen treatment, ovulation, and nursing, as well as playing a role in metabolism, regulation of the immune system, and pancreatic development.

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The Chaos to Expect without the Hypothalamus In Charge

Too much Growth Hormone leads to acromegaly which is a disorder in adults. It leads to over excessive growth. It is first noticed in the hands and the feet, but the internal organs can also be affected. Over secretion in children can cause gigantism, causing them to grow to extreme measures in inappropriate proportion to their age. Children with gigantism can have issues with delayed puberty, double vision, or problems with peripheral vision, frontal bossing, large hands and feet, thick fingers and toes, gaps between the teeth, and a prominent jaw.

Deficiency of Growth Hormone happens in bones in children and adults. In children this can be caused by a genetic mutation, in adults this is normally linked with structural or functional abnormalities of the pituitary gland. In children this can cause growth failure and hypopituitary dwarfism. In adults, symptoms are less noticeable such as social withdrawl, fatigue, loss of motivation, diminished feeling of well being, osteoporosis, as well as alterations in body composition.


Too much anti-diuretic hormone results in retention of water in the kidneys. When excess ADH is released when it is not needed it causes a condition called syndrome of inappropriate anti-diuretic hormone secretion (SIADH) which is a type of hyponatremia. In this condition the water retention causes dilution of the blood causing low salt concentration. Too much ADH can be caused by drug side effects and diseases of the lungs, chest wall, hypothalamus, or pituitary.

Low levels of anti-diuretic hormone will cause the opposite, making the kidneys release too much water. This causes urine volume to decrease, leading to dehydration and decrease in BP. Low levels of ADH indicate pituitary and hypothalamus damage, as well as primary polydipsia. A condition that can cause decreased ADH is diabetes insipidus, usually due to a tumor, trauma, or inflammation in the pituitary or hypothalamus.


Too much corticotrophin-releasing hormone can cause nervous problems, anxiety, sleep disturbances, and anorexia. High levels of the hormone can cause inflammatory problems to get worse. These type of problems include rheumatoid arthritis, psoriasis, ulcerative colitis, and chron's disease.

Low corticotrophin-releasing hormones has been shown to play a role in Alzheimer patients. Lack of corticotrophin-releasing hormones can also cause chronic fatigue syndrome (sometimes called myalgic encephalomyelitis). People with chronic fatigue syndrome present with sleep, memory, and concentration problems. During pregnancy low corticotrophin-releasing hormone results in miscarriage.


There is no known case of too much thyrothrophin-releasing hormone (TRH). However, decreased amounts of TRH can cause development of hypothyroidism (thyroid under activity), but this is a rare scenario usually resulting from an injury or tumor that destroys this specific area of the hypothalamus. When this occurs, it is referred to as secondary or central hypothyroidism.

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Diagnostics and Treatment (Crisis Control)

Diagnosis of hypo and hyper secretion and activity of any of these hormones can be found by various tests. Each of these hormones can be tested for in blood work. You can test the patient's blood for the increased or decreased levels of the specific hormone or you can test for the hormones that are affected by these increases or decreases. For example, if a patient is suspected of having increased GH, the health care provider would preform a blood test and a OGTT (oral glucose tolerance test) in which the patients glucose and GH levels would be measured initially and after intake of a glucose beverage. After the drink the patient's glucose and GH levels are tested again to determine if they are producing too much GH. Normally after consumption of that much glucose, a patient's GH levels would decrease. If the levels do not decrease, then the patient is suspected of hyperactivity, meaning growth hormone releasing hormone is malfunctioning.

Health care providers can also look for the physical findings and assessment of the signs and symptoms, as well as patient history for diagnostics. To rule out or discover tumor growth or injury to the hypothalamus, causing the decrease or increase, patient can also undergo MRIs or CT scans.


There are also a variety of treatments for hyper and hypo activity of these hormones such as removal or excision of tumors if possible. If surgical excision is not possible, you can reduce tumor size or sometimes remove tumor with growth hormone blocking injections or radiation to the tumor. Treatments depend on the specific disorder, and medication treatment generally focuses on adjusting hormone balance using synthetic hormones.

Special Thanks
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References

Huether, S., & McCance, K. (2008). Understanding pathophysiology (5th ed.). St. Louis, MO: Mosby/Elsevier.


You & Your Hormones | Home. (2012, September 1). Retrieved November 21, 2015, from http://www.yourhormones.info/


All Endocrine Disorders. (n.d.). Retrieved November 21, 2015, from http://www.endocrineweb.com/conditions


Johns Hopkins Medicine, based in Baltimore, Maryland. (n.d.). Retrieved November 21, 2015, from http://www.hopkinsmedicine.org/


Medscape. (n.d.). Retrieved November 21, 2015, from http://www.medscape.com/


Nursing apps for iPhone, iPad, Android - Unbound Medicine. (n.d.). Retrieved November 20, 2015, from http://www.unboundmedicine.com/products/nursing