The thyroid is a butterfly-shaped gland that lies in front of the windpipe (trachea), just below the voice box. The parathyroid glands are four tiny glands located behind the thyroid gland. The parathyroid glands produce a substance (parathyroid hormone) that helps control the amount of calcium in the blood.
Earth's atmosphere helps maintain a constant temperature.
The organ that is important in processing substances after being absorbed during digestion is the liver.
all living things are composed of cells
cells are the basic units of structure and function in living things
all cells are produced from other cells
