where is the most of the iodine in the body concentrated
Iodine in biology Iodine's main role in vertebrate biology is as constituents of the thyroid hormones, thyroxine (T4) and triiodothyronine (T3). These are made from addition condensation products of the amino acid tyrosine, and are stored prior to release in an iodine-containing protein called thyroglobulin. T4 and T3 contain four and three atoms of iodine per molecule, respectively. The thyroid gland actively absorbs iodine from the blood to make and release these hormones into the blood, actions which are regulated by a second hormone TSH from the pituitary. Thyroid hormones are phylogenetically very old molecules which are synthesized by most multicellular organisms, and which even have some effect on unicellular organisms.
Eccrine sweat gland Eccrine glands (/ˈɛkrən/, /ˈɛˌkraɪn/, or /ˈɛˌkrin/; from ekkrinein "secrete";[3] sometimes called merocrine glands) are the major sweat glands of the human body, found in virtually all skin, with the highest density in palms and soles, then on the head, but much less on the trunk and the extremities. In lower mammals, they are relatively sparse, being found mainly on hairless areas such as foot pads. They reach their peak of development in humans, where they may number 200–400/cm² of skin surface.[4][5] They produce a clear, odorless substance, consisting primarily of water.