4. A man in his 40s begins to notice that he is tired all the time and that he i
ID: 3523340 • Letter: 4
Question
4. A man in his 40s begins to notice that he is tired all the time and that he is gaining weight. He is somewha depressed and he has some joint pain. His doctor orders a TSH test. a. What does TSH do? The TSH test comes back showing higher than normal levels of TSH. The doctor explains that TRH, TSH and T are involved in a negative feedback loop, where high levels of T, inhibit the release of TRH from the hypothalamus. b. Why does a lack of T4 lead to an increase in TSH? Would you expect his TRH levels to be low or high? Why? C. d. The doctor believes the man has hypothyroidism. From its name, what do you think is wrong with his thyroid gland? 5. Why does a lack of iodine lead to enlargement of the thyroid?Explanation / Answer
Answer 4)
a) TSH (thyroid stimulating hormone) is released from pituitary glands, and acts upon tyroid gland to release thyroxine hormones.
The symptoms such as depression, joint paint and weight gain indicates hypothyroidism in the patient. Due to lack of thyroxine, metabolism is affected resulting in wieght gain.
Thus, doctor suggestes TSH test to determine the release to thyroxine from thyoid gland.
b) When there is low T4 levels in brain, negative feedback mechanism works. Low T4 levels signals hypothalamus to release more TRH ( Thyrotropin releassing hormone. TRH will trigger TSH release from pituitary gland.
Thus, in influence of TRH, there are high levels of TSH in lack of T4.
c) TRH levels will be high becuase in the influence of TRH, pituitary is releasing TSH.
Negative feedback works on hypothalamus to incresase TRH levels.
Hence, there will be high TRH levels.
d) Hypothyroidism means less thyroid gland secretions. The gland has to function by releasing thyroxine hormones but the gland is underactive. This term suggests that thyroid gland is unable to produce adequate amount of thyroid hormones.
Answer 5)
Iodine facilates the release of thyroxine. When there are low iodine levels in body, it influences the release of thryoid hormones and they are secreted in very low amounts. As a result of this, hypothyroidism occurs. This stimulates hypothalamus to secret TRH, eventuaally pituitary secrets high TSH levels.
Under the influense of TSH, thyroid gland increases many biochemical processes, the cellular growth and proliferation results in the swelling and enlargement of thyroid gland.
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