The primary function of the thyroid is the production of the iodine-containing thyroid hormones, triiodothyronine (T3) and thyroxine (T4) and the peptide hormone calcitonin. 1  T3 is so named because it contains three atoms of iodine per molecule and T4 contains four atoms of iodine per molecule.
Explorations of Africa. In the official role of a medical missionary, he set forth to Africa, arriving in Cape Town, South Africa in March of 1841. A few years later, he married Mary Moffat; the couple would have several children.
At the end of the 15th century the Portuguese started to explore the west coast of Africa. They set up trading posts and collected gold and silver. They were convinced that by sailing around the coast of Africa they would find a route to India. In 1487, the Portuguese explorer Bartholomeu Dias sailed around the southern part of the continent and got as far as the east coast of Africa, but a storm made him turn back.