BIOL 4390 Assignment Quiz 5 (15 pts) Due 7/19/18 in class as hardcopy - 2 pts/da

Question

BIOL 4390 Assignment Quiz 5 (15 pts) Due 7/19/18 in class as hardcopy - 2 pts/day late] 1. In Grave's Disease, hyperthyroidism is produced by an IgG that causes prolonged activation of the TSH receptors and results in excessive secretion of T, and T Explain why the negative feedback mechanism does not work in this disease. Reference an internet source (URL), journal article or book (5 points) 2. Chromatographic assay reveals that the total amount of T in the blood is 10 ug. You find that the various bound forms of the hormone are: 3(free,-0.5% T, ~ albumin-12 % T,~TBG 69 % and T-pro-albumin-18.5 % Target tissue: heart whose Bx of T, receptors 76 fmol of T receptor/mg protein have 100 ug protein (total protein of which T, receptors makes only a tiny fraction) in your heart assay. MW 68 kDal 68,000 g/mol [Dasmalopatra et al., Receptor, 2(4):213-223 1992 This reference is only for the MW of T, receptor, and not for the solution to this question. Note: You won't need the MW of T, because you already have the amount in g This is another conceptual question. So, don't get all caught up in equations. In fact, don't use the equations I provided in lecture, 6MemR. If you had freshman chemistry or physics (and all of you should have), then you can solve the following: Calculate the amount in g) of available T, and its receptor (also in g). How do the 2 amounts compare? Will Bmx be reached (10 points)? ( fmol 1015 mol, where you

Explanation / Answer

1.Graves disease is an autoimmune disease in which the B cells of our body produces TSI's(thyroid stimulating ig)=these bind into te TSH receptors--> and act like TSH and there is production of T3 and T4 hormone

2.Now T4 i.e thyroxine gets converted to T3--> leadin to protein synthesis

3.Thus,increased levels of T3 and T4 in blood--> leads to activation of negative feedback mechanism--> but this negative feedback mechanism fails--> because it is an autoimmune disease--> the B cells with their action of producing TSI's --> leading to overstimulation of thyroid hormones i.e T3 and T4

4.These antibodies that are produced bind to TSH receptors--> but they do not cause destruction of cells--> instead they stimulate te receptors to cause production of more T3 and T4

5.The negative feedback mechanism will lead to low TSH levels and also low TRH level(TRH=Thyrotropin releasing hormone)

6.Now,inspite of low TSH levels, te levels of T3 and T4 remain high because the stimulation of thyroid gland is independant of TSH

7.Therefore,in grave's disease there is low level of TSH and high levels of T3 and T4 leading to hyperthyroidism as negative feedback loop acts by decreasing levels of TSH but the autoimmune activity continues

Reference:- Textbook of Pathology by Dr Harsh Mohan

Textbook of Surgery by K.Rajgopal Shenoy

http://en.m.wikipedia.org

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