The Thyroid itself secretes three main hormones: 1  Thyroxine contains iodine which is essential for the body's normal growth, and metabolism. 2  Triiodothyronine has similar functions to thyroxine. 3  Calcitonin causes a decrease in the concentration of calcium in the blood.
acre. acre, measure of land area used in the English units of measurement. The acre was originally the area a yoke of oxen could plow in a day and therefore differed in size from one locality to another.It is now fixed as 10 square chains or 160 square rods, i.e., 4,840 sq yd, 43,560 sq ft, or 1/640 sq mi. Share | Cite. acre, measure of land area used in the English units of measurement. The acre was originally the area a yoke of oxen could plow in a day and therefore differed in size from one locality to another. It is now fixed as 10 square chains or 160 square rods, i.e., 4,840 sq yd, 43,560 sq ft, or 1/640 sq mi.
An acre is a unit of area primarily used in the imperial and U.S. customary measurement systems. It is equal to 4,047 square meters, 4,840 square yards, 0.405 hectares, 1/640 or 0.0015625 square miles. The acre is defined in square units because it is a measure of area and not length, and it can take any shape.