| Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle | |
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عدد المساهمات : 9444 تاريخ التسجيل : 06/08/2009
| موضوع: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle الإثنين أكتوبر 18, 2010 8:14 pm | |
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عدل سابقا من قبل Admin في الإثنين مارس 21, 2016 10:23 pm عدل 2 مرات | |
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عدد المساهمات : 9444 تاريخ التسجيل : 06/08/2009
| موضوع: رد: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle الإثنين أكتوبر 18, 2010 8:25 pm | |
| how parathyroid hormone is regulated
The dominant regulator of PTH is plasma Ca2+. Secretion of PTH is inversely related to [Ca2+]. Maximum secretion of PTH occurs at plasma Ca2+ below 3.5 mg/dL. At Ca2+ above 5.5 mg/dL, PTH secretion is maximally inhibited.
PTH secretion responds to small alterations in plasma Ca2+ within seconds. A unique calcium receptor within the parathyroid cell plasma membrane senses changes in the extracellular fluid concentration of Ca2+. This is a typical G-protein coupled receptor that activates phospholipase C and inhibits adenylate cyclase—result is increase in intracellular Ca2+ via generation of inositol phosphates and decrease in cAMP which prevents exocytosis of PTH from secretory granules.
When Ca2+ falls, cAMP rises and PTH is secreted. 1,25-(OH)2-D inhibits PTH gene expression, providing another level of feedback control of PTH. Despite close connection between Ca2+ and PO4, no direct control of PTH is exerted by phosphate levels.
عدل سابقا من قبل Admin في الأربعاء أكتوبر 14, 2015 6:32 am عدل 1 مرات | |
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عدد المساهمات : 9444 تاريخ التسجيل : 06/08/2009
| موضوع: رد: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle السبت يونيو 02, 2012 4:55 am | |
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عدل سابقا من قبل Admin في الأربعاء أكتوبر 14, 2015 6:32 am عدل 1 مرات | |
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عدد المساهمات : 9444 تاريخ التسجيل : 06/08/2009
| موضوع: رد: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle الأربعاء أكتوبر 14, 2015 6:32 am | |
| WHY DOES POLYPHAGIA OCCUR WITH DIABETES MLLITUS? =========== ANSWER: ======= First reason for polyphagia: is the intracellular starvation. As in diabetes either there is absence or the resistance to insulin action so glucose cannot move into the cells and thus cells are starved of glucose.The cellular response to glucose starvation manifests in the form of frequent hunger pangs. Body cells use hormones like leptin and orexin to stimulate the hypothalamus of the brain, which eventually causes the desire to eat food. Thus, hunger signals sent out by the body cells and then received by the brain, is what causes excessive eating in diabetic patients.
Second reason can be: the "Glucostat theory of feeding regulation". According to this theory arteriovenous difference of glucose in the hypothalamic satiety and feeding centers regulate the feeding response. If the difference is high due to the reason that glucose is more utilized by satiety center, the satiety center is activated. And if the difference is low then feeding center is activated. In diabetes due to insulin resistance or absence of insulin, glucose cannot move into the satiety center thus the arteriovenous difference remains low and the feeding center is chronically active.
Thus polyphagia occurs. | |
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عدد المساهمات : 9444 تاريخ التسجيل : 06/08/2009
| موضوع: رد: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle الثلاثاء ديسمبر 08, 2015 6:36 am | |
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عدد المساهمات : 9444 تاريخ التسجيل : 06/08/2009
| موضوع: رد: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle الثلاثاء ديسمبر 29, 2015 5:42 pm | |
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عدد المساهمات : 9444 تاريخ التسجيل : 06/08/2009
| موضوع: رد: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle الثلاثاء يناير 26, 2016 9:30 pm | |
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عدد المساهمات : 9444 تاريخ التسجيل : 06/08/2009
| موضوع: رد: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle الإثنين مارس 07, 2016 10:40 am | |
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عدد المساهمات : 9444 تاريخ التسجيل : 06/08/2009
| موضوع: رد: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle الإثنين مارس 21, 2016 10:26 pm | |
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عدد المساهمات : 9444 تاريخ التسجيل : 06/08/2009
| موضوع: رد: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle الأحد مارس 27, 2016 4:04 pm | |
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عدد المساهمات : 9444 تاريخ التسجيل : 06/08/2009
| موضوع: رد: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle الإثنين مايو 02, 2016 5:56 am | |
| Question
What is priapism? ================ Answer
Priapism is a potentially painful medical condition in which the erect penis does not return to its flaccid state, despite the absence of both physical and psychological stimulation, within four hours. It may be associated with haematological disorders, especially sickle-cell disease, sickle-cell trait, and other conditions such as leukemia, thalassemia, and neurologic disorders such as spinal cord lesions and spinal cord trauma. It may also be associated with glucose-6-phosphate dehydrogenase deficiency, which leads to decreased NADPH levels. NADPH is a co-factor involved in the formation of nitric oxide, which may result in priapism. Raised levels of adenosine may also contribute to the condition by causing blood vessels to dilate, thus influencing blood flow into the penis.
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عدد المساهمات : 9444 تاريخ التسجيل : 06/08/2009
| موضوع: رد: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle السبت مايو 21, 2016 6:47 am | |
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عدد المساهمات : 9444 تاريخ التسجيل : 06/08/2009
| موضوع: رد: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle الخميس أكتوبر 06, 2016 9:34 am | |
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عدد المساهمات : 9444 تاريخ التسجيل : 06/08/2009
| موضوع: رد: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle الجمعة أكتوبر 07, 2016 8:56 am | |
| Question Mention the cause of menstrual disorders in thyroid dysfunction =================== Answer
Thyroid dysfunction is associated with a range of menstrual abnormalities, including oligomenorrhea, amenorrhea, and menorrhagia. Women with hypothyroidism may also be at increased risk of pregnancy loss. The connection between thyroid hormone levels and the menstrual cycle is mainly mediated by thyrotropin-releasing hormone (TRH), which has a direct effect on the ovary. Additionally, abnormal thyroid function can alter levels of sex hormone-binding globulin, prolactin, and gonadotropin-releasing hormone, contributing to menstrual dysfunction. For example, increased levels of TRH may raise prolactin levels, contributing to the amenorrhea associated with hypothyroidism.
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عدد المساهمات : 9444 تاريخ التسجيل : 06/08/2009
| موضوع: رد: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle الإثنين نوفمبر 14, 2016 6:40 am | |
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عدد المساهمات : 9444 تاريخ التسجيل : 06/08/2009
| موضوع: رد: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle الثلاثاء نوفمبر 22, 2016 5:28 pm | |
| Questions Why testosterone has higher plasma level than DHT Why testosterone-receptor complexes are less stable in target cells ======= Answer
The enzyme 5α-reductase catalyzes the formation of Dihydrotestosterone (DHT) from testosterone in certain tissues including the prostate gland, seminal vesicles, epididymides, skin, hair follicles, liver, and brain Thus, logically the substrate (testosterone) is more than the product (DHT).
===== DHT has an affinity to the human androgen receptor (AR) of about 2- to 3-fold higher than that of testosterone .The dissociation rate of DHT from the AR is 5-fold slower than that of testosterone. The half maximal effective concentration (EC50, the concentration of the hormone which induces a response halfway between the baseline and maximum after a specified exposure time) of DHT for activation of the AR is about 5-fold higher than that of testosterone.
The biological half-life (terminal half-life, the time taken by a substance to lose half of its physiologic, activity) of DHT in the body (53 minutes) is longer than that of testosterone (34 minutes), and this may account for some of the difference in their potency
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عدد المساهمات : 9444 تاريخ التسجيل : 06/08/2009
| موضوع: رد: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle السبت يناير 07, 2017 8:10 am | |
| Question: ======= WHICH HORMONE IS RESPONSIBLE FOR MALE SECONDARY SEX CHARACTERS, DHT OR TESTOSTERONE? ======================================= Answer: ====== Testosterone and DHT are important for sexual development as well as secondary sexual characteristics such as thick skin and male-pattern hair growth ========= For DHT: -During male embryogenesis, DHT has an essential role in the formation of the male external genitalia. -In the adult male, DHT acts as the primary androgen in the prostate gland, seminal vesicles, skin, and hair follicles. -In congenital 5α-reductase deficiency, male pseudohermaphroditism results. It presents with underdeveloped male genitalia and prostate. Males with this condition are often raised as girls due to their lack of conspicuous male genitalia. At the onset of puberty, although their DHT levels remain very low, their testosterone levels elevate normally. Their musculature develops like that of other male adults. After puberty, men with this condition have a large deficiency of pubic and body hair and reportedly no incidence of androgenic alopecia (pattern hair loss). ========= For Testosterone: -It plays a key role in the development of male reproductive tissues such as the testis and prostate, as well as promoting secondary sexual characteristics such as increased muscle and bone mass, and the growth of body hair. -In addition, it is essential for health and well-being, and for the prevention of osteoporosis. -Insufficient levels of testosterone in men may lead to abnormalities including frailty and bone loss.
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عدد المساهمات : 9444 تاريخ التسجيل : 06/08/2009
| موضوع: رد: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle الخميس فبراير 09, 2017 8:37 am | |
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عدد المساهمات : 9444 تاريخ التسجيل : 06/08/2009
| موضوع: رد: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle الإثنين مايو 08, 2017 9:59 pm | |
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عدد المساهمات : 9444 تاريخ التسجيل : 06/08/2009
| موضوع: رد: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle الإثنين أكتوبر 09, 2017 9:28 am | |
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| موضوع: رد: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle الأحد ديسمبر 17, 2017 8:33 pm | |
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| موضوع: رد: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle الجمعة سبتمبر 21, 2018 11:33 am | |
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| موضوع: رد: Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle السبت أبريل 09, 2022 10:32 am | |
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| Questions and answers on endocrine & Reproduction Physiology by dr khaled Abulfadle | |
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