Deficiency of iodine in the diet results in a goiter (an enlarged thyroid gland).Which of the following statements offers the best explanation for this phenomenon?
A)The thyroid enlarges so that it can secrete more thyroid hormones to compensate for the lack of iodine
B)Decreased plasma iodine levels are detected by the hypothalamus, which stimulates the anterior pituitary to secrete more thyroid stimulating hormone
C)Without iodine, the thyroid gland cannot produce thyroid hormones.Thyroid hormones normally act as a negative-feedback signal for the hypothalamus and pituitary gland.Loss of this signal results in excessive secretion of thyroid stimulating hormone
D)All of the choices are correct
E)None of the choices are correct

Question

Quizplus · Accepted Answer

Without iodine, the thyroid gland cannot produce thyroid hormones. Thyroid hormones normally act as a negative-feedback signal for the hypothalamus and pituitary gland. Loss of this signal results in excessive secretion of thyroid stimulating hormone, which leads to the enlargement of the thyroid gland and the development of a goiter. The thyroid gland enlarges in an attempt to increase its capacity to absorb iodine and produce thyroid hormones, but without sufficient iodine, this mechanism fails, leading to the enlargement of the gland.

Deficiency of Iodine in the Diet Results in a Goiter