Hypothalamo-pituitary axis

ENDOCRINE AXISHYPOTHALAMIC- PITUITARYADRENAL AXIS. THE NEUROENDOCRINE SYSTEM FEEDBACK LOOPS NEUROENDOCRINE AXIS NEUROENDOCRINE AXIS HPA AXIS HPT AXIS HPG AXIS HPA AXIS It is a complex set of direct influences and feedback interactions between the hypothalamus, the pituitary gland and the adrenal gland. This complex communication system is responsible for effectively handling stress by regulating the production of cortisol, neurotransmitters and key hormones. HPA AXIS (OVERACTIVITY) In the following conditions HPA axis can be overactive: Depression Stress Disorder Anxiety Disorders Dementia When the HPA axis is overactive the Negative feedback gets progressively weaker. Leading to deterioration of Cognitive Functions. HPA Burn-out Syndrome HYPOTHALAMO ANTERIOR PITUITARY THYROID GLAND AXIS Thyroid Hormones The thyroid gland produces thyroid hormones. These are peptides containing iodine. The two most important hormones are tetraiodothyronine (thyroxine or T4) and triiodothyronine (T3). These hormones are essential for life and have many effects on body metabolism, growth and development. Thyroid Disorders Too much thyroid hormone production or hyperthyroidism. Too little thyroid hormone production or hypothyroidism The state of normal thyroid functions is called euthyroidism. HYPOTHALAMO PITUITARY GONADAL AXIS LH and FSH from the anterior pituitary stimulate the gonads (ovaries and testes). LH stimulates the testes to produce several kinds of steroid hormones called androgens. One of these androgens is testosterone, the main sex hormone in males. LH stimulates the ovaries produce estrogen and progesterone, the female sex hormones. DEPRESSION Major depression is associated with a dysfunction of the serotonergic activity and the hypothalamic-pituitary-adrenal (HPA) axis, dysfunction in 5-HT(1A) receptor activity could be due to a hypersecretion of cortisol. Increased CRF synthesis and secretion lead to a chain of events, starting from enlargement of the pituitary gland with increased ACTH secretion, and leading to enlargement of the adrenal cortex with increased baseline cortisol levels. This results in alterations in the glucocorticoid receptors, which become less functional, or downregulated, or "glucocorticoid resistant," in depressed patients. Psychoneuroimmunology plays an important role in depression. INTERACTION OF THE HPA AXIS AND SLEEP The hypothalamic-pituitary-adrenal (HPA) axis plays important roles in maintaining alertness and modulating sleep. Dysfunction of this axis at any level (CRH receptor, glucocorticoid receptor, mineralocorticoid receptor) can disrupt sleep. HPA axis hyperactivity may be lead to insomnia. THE IMMUNE SYSTEM AND HPA AXIS The HPA axis interacts with the immune system making it more vulnerable to colds and flu, fatigue and infections. High cortisol from prolonged stress could make the body more susceptible to diseases due to deactivation of WBC. STRESS CORTISOL - Cortisol is a major stress hormone. Cortisol responds to life threatening physical stress. Increased level of cortisol can break the body down and increase the risk of diseases. THE STRESS PATHWAYS The stress response begins in both the nervous system and the endocrine system. The two major stress response systems are the sympathetic-adrenal medullary (SAM) system and the hypothalamic-pituitary-adrenal (HPA) axis. To create homeostatic balance. (cortisol) HPA AXIS AND GIT (STRESS) A variety of stressor types play a role in the development of irritable bowel syndrome (IBS). HPA axis can also result in digestive problems. CRH directly hinders the release of stomach acid secretion and emptying of the stomach. High secretion of cortisol can increase the appetite and weight gain. Stress affects the intestinal flora. DISEASE INVOLVED DUE TO IMBALANCE IN HORMONAL SECRETION OF HPA AXIS ACROMEGALY HYPERPROLACTINAEMIA CUSHING’S SYNDROME ADDISON’S DISEASES HYPERTENSION HYPOPITUITARISM ACROMEGALY • Acromegaly is the clinical condition which results from prolonged, excessive circulating levels of growth hormone(GH) in adults. CUSHING’S SYNDROME Cushing's syndrome is a hormonal disorder caused by prolonged exposure of the body's tissues to high levels of the hormone cortisol. It is also called as "hypercortisolism," It results in obesity and muscle weakness. CUSHING’S SYNDROME ADDISON’S DISEASES Addison's disease occurs when the adrenal glands, which are located just above the kidneys, do not produce enough of the hormone cortisol and in some cases, the hormone aldosterone. HYPERTENSION ASSOCIATED WITH ABNORMALITIES OF THE HPA AXIS 17-hydroxylase (17-OH) deficiency syndrome is a rare genetic disorder of steroid biosynthesis causing decreased production of glucocorticoids and sex steroids and increased synthesis of mineralocorticoid precursors. Excessive mineralocorticoid activity produces varying degrees of hypertension and hypokalemia. Patients usually are diagnosed with this condition during an evaluation of delayed puberty, absent secondary sexual characteristics or primary amenorrhea. THE RENIN ANGIOTENSIN ALDOSTERONE SYSTEM The renin-angiotensinaldosterone system (RAAS) is a hormone system that helps regulate long-term blood pressure and extracellular volume in the body. It triggers the release of the hormone aldosterone from the adrenal glands and antidiuretic hormone from the pituitary gland. SUMMARY  The HPA axis acts as the body's energy regulator. . suppressed, the body will  When the HPA axis becomes not be able to properly regulate stress and energy levels, which can manifest in fatigue, suppressed immune system, depression and anxiety.  The HPA axis is linked to the proper functioning of all organ systems it plays a very important role in normal homeostasis ,that is maintaining the proper physiology of the body. BIBLIOGRAPHY Books referred - Name of the book: Clinical endocrinology Authors: G Michael Besser Michael O Thorner Foreword by : David N Orth Edition:2nd edition Publisher: Times mirror international publishers Ltd. 1) - Name of the book :Human Physiology Authors: Andrew Davies Asa G. H. Blakeley Cecil Kidd Publisher: CHURCHILL LIVINGSTONE 2)Websites referred : http://www.besthealth.com/besthealth/bodyguide/reftext/html/endo_sys_fin.html http://ajpgi.physiology.org/cgi/content/full/280/4/G519 www.biopsychiatry.com/hpasui.html www.neuroendo.org.uk/content/view/31/11/ www.mind-body-health.net/hpa.html “It is not stress that kills us it is our reaction to it. Adopting the right attitude can convert a negative stress into a positive one.” -Hans Selye STRESS TEST With ever-increasing demand in the energy industry and the constant pressure to do more with less we at PRCTL thought the following Stress Test might be useful. The test was developed by a team of world renown psychologists and is amazingly accurate. It was used in a case study on stress level at St. Mary's Hospital. There is a link to a picture on the bottom of the page. The picture has 2 identical dolphins in it. Look at both dolphins jumping out of the water. The dolphins are identical. A closely monitored, scientific study of a group revealed that in spite of the fact that the dolphins are identical; a person under stress would find differences in the two dolphins. If there are many differences found between both dolphins, it means that the person is experiencing a great amount of stress. Hope you got a good laugh! On a serious note, laughter is a great way to reduce stress and boost immune function. Next time you're feeling overwhelmed, call a friend who makes you chuckle or head off for a comedy club. You'll feel better for it!