Question

Examine your thyroid-pituitary diagram, Remember that TSH is released at a constant moderate level in order to maintain normal thyroxin levels in the blood. a. What would be the immediate result of high TSH level on thyroxin level? b. How would the feedback mechanism function to restore homeostasis after high TSH levels? Include receptor details. c. what would be the immediate result TSH level? d. How would the feedback mechanism function to restore homeostasis after low TSH levels? Include receptor details. e. Summarize: Which of the two gland systems is considered to be "on" until it is turned "off"?

Answer 1

Answer: a) High TSH increases Thyroxine (T4) in the blood.

B)When large amount of TSH is released from the anterior pituitary gland it acts on thyroid gland and increases thyroxine release from it. This increased thyroxine in blood causes a decrease in release of TSH from pituitary gland by *negative feedback* mechanism.

Receptor details: T3 and T4 receptors on the anterior pituatry

And TSH receptor on the thyroid gland.

C) After the immediate relase of TSH thyroxine relase increases but after negative feedback mechanism

It would decrease.

D) when the TSH level decreases in blood, TRH (thyroid releasing hormone) from the hypothalamus is released and it acts on the pituatry to increase the TSH secretions.

Receptor details: TRH receptors on the pituarty and TSH receptors in the hypothalamus.

e) anterior pituatry is considered to be on until the thyroid gland is turned off.

Explanation:

TRH is released from hypothalamus which acts on anterior pituatry which causes the release of TSH in blood ... This TSH in blood acts on the thyroid gland whoch causes the release of thyroxine and increases the level of thyroid hormones in blood.