Wednesday, September 9, 2009
Tuesday, August 25, 2009
1. What is the physiological inhibition loop that controls the suppression and regulation of most endocrine hormones?
2. When TRH is released into the portal system it directs the thyrotrophs in the anterior pituitary to secrete ______________.
3. After negative feedback mechanism has occurred the hormone levels will tend to be _________.
4. When thyroxine is released in the blood and circulates to the hypothalamus and pituitary to suppress further ______ and ______ production.
5. The mechanism mainly depends on factors which maneuver the ________ and ______ of the hormones.
True or False
6. The high concentration of the hormone alone will trigger the negative feedback mechanism.
7. Negative feedback is generally termed as the response of the system in the same direction.
8. Negative feedback must be triggered by the effect and result of overproduction of the hormone.
9. Its major function is to bring the hormone levels back within the normal range.
10. Hypothalamic-pituitary-thyroidal axis is an example of an endocrine negative feedback loop.
Discuss briefly what happens in the homeostatic negative feedback loop when a person’s thyroid hormone levels increases in the blood’s circulation.
Original Photo: by dube1111
Thursday, August 13, 2009
Negative Feedback Mechanism
- It’s the physiological inhibition loop controlling most of the endocrine hormones. In negative feedback, any change or variation from the normal range of function is divergent, or resisted. The change or variation in the controlled value signals the response that brings the function of organ back within the normal range. The mechanism primarily depends on factors which manipulate the metabolism and flow of the hormones. Therefore, the high concentration of the hormone alone will not trigger the negative feedback mechanism because it must be triggered by the effect and result of overproduction on the hormone.
A simple example of an endocrine feedback loop is the hypothalamic-pituitary-thyroidal axis. The hypothalamus produces the hypophysiotropic hormone, thyrotropin-releasing hormone (TRH), and releases it into the portal system where it directs the thyrotrophs in the anterior pituitary to secrete thyroid-stimulating hormone (TSH). TSH circulates to the thyroid and stimulates several steps in the thyroid that are critical in the production and release of thyroid hormone. Thyroxine is released in the blood and circulates to the hypothalamus and pituitary to suppress further TRH and TSH production.
References: Fundamentals of Clinical Chemistry by Bishop et al
Clinical Laboratory Diagnosis by John Bernard Henry et al (19th Edition)
Images: original is File:ACTH Negative Feedback.jpg
Tuesday, July 28, 2009
1. Doctor Z of Zorlone- His blog is very inspiring and I would always love to read his poems which are simple yet they are able to make every reader enjoy reading his blog.
2. Roy The Struggling Blogger- I would say that this blog is a must see and read. One of my favorite blog because of the topics that are being posted are magnificently done.
3. Jan Geronimo of WritingToExhale- Reading this blog makes me think "how would a person be this very creative?". Very nice blog.
4. Angel Cuala of Father Blogger dot com-Family matters, is this blog all about. One of the blog that I always read and I also let my friends read his blog because it can help a lot especially to us teenagers.
5. Irene of LifeLots- I love the way she uses her everyday learning to inspire us and share life's ups and downs.
6. Luke of A Walk In The Dark- Very informative blog. I think this man is born to be a blogger. Two thumbs up for his works.
7. Holly Jahangiri of It’s all a matter of Perspective: Mine- Wide range of topics are being discussed. One of the must read.
8. Bingkee of I Love/Hate America- I have seen lots of blogs but I would tell that this is one of the best blog to read. Topics are very well discussed and very interesting to read.
9. Kelvin Servigon of Kelvinonian Ideas 2.0- Most of his blog are about updates on new gadgets and technology in our era. Which made me visit his blog more often. Very influential I suppose.
10. Dee of Tales From The Mom Side- Another nice piece of art. I am sure that the topics are being read by lots of moms.
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Tuesday, July 14, 2009
Tuesday, June 30, 2009
3-4. Pituitary dwarfism and Hypopituitarism
5. Skeletal muscles
7. Laron's dwarfism
8. <5 ng/ml
9. 2-3 hours
Tuesday, June 16, 2009
2. The secretion of growth hormone is at its peak during ________.
3-4. Give two conditions which are caused by decreased levels of growth hormone.
5. Enhanced protein synthesis in this site is caused by the anabolic effects of growth hormone.
6. A coarse thickening of the bones of the skull, hands and feet over the course of years to decades.
7. An autosomal recessive disorder characterize by insensitivity to growth hormone, caused by a deviation of the growth hormone receptor. This disorder is associated with increased levels of GH.
8. Normal values of growth hormone in adult males?
9. Growth hormone is secreted in pulses, with an average interpulse interval of____ hours?
10. Obesity and the use of many drugs will cause false _______ result in the growth hormone suppression test.
A 48-year-old man seeks care for evaluation of muscle weakness, headaches, and excessive sweating. He has poorly controlled hypertension and, on questioning, admits to noticing a gradual increase in both glove and shoe size, as well as a reduction in libido. A review of older photographs of the man documents coarsening of facial features, progressive prognathism and broadening of the nose. Acromegaly is suspected.
1. What screening tests are available?
2. What is the definitive test for autonomous growth hormone production?
3. Because the patient complains of reduced libido, hypogonadism is suspected. What evaluation is appropriate?