Deficiency of Iodine in the Diet Results in a Goiter

question 53

Multiple Choice

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

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Definitions:

Median

The middle value in a set of numbers, which separates the higher half from the lower half of the data set.

Upper Quartile

A statistical measure indicating the value below which 75% of the data in a data set falls, marking the top end of the middle 50% of data.

Lower Quartile

The value below which 25% of the data falls, marking the lower end of the middle 50% of a dataset.

Median

The middle value in a list of numbers, which separates the higher half from the lower half.