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.
David Livingstone was born on March 19, 1813, in Blantyre, South Lanarkshire, Scotland, and grew up with several siblings in a single tenement room.
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.