alleryStart learning →Which comparison of triiodothyronine and thyroxine is correct?
AT3 holds four iodines and is the more potent
BT3 holds three iodines and is the more potent
CT4 holds three iodines and is the more potent
DT4 holds two iodines and is the less potent
Answer & Solution
Correct answer: B. T3 holds three iodines and is the more potent
1. Both hormones are assembled in the colloid from iodinated tyrosines on thyroglobulin.
2. Triiodothyronine carries three iodines, which its name states directly.
3. Thyroxine, also called tetraiodothyronine, carries four.
4. Many cells convert thyroxine to triiodothyronine by removing one iodine atom.
5. That conversion happens because triiodothyronine is the more potent of the two.
6. Options that give thyroxine three iodines or triiodothyronine four simply swap the two names, and thyroxine is the more abundant hormone rather than the more potent one.
_Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 17 "The Endocrine System", section 17.4 The Thyroid Gland_
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