The thyroid gland is an organ shaped like a butterfly that can be found in our necks. More specifically, it’s inferior to the larynx–aka the voice box–and anterior to the trachea, which is also colloquially known as the windpipe.
The thyroid’s medial region is known as the isthmus; on either side are its left and right lobes, which look like wings. The parathyroid glands are embedded within these lobes, and are mostly found on their posterior surfaces. For the most part, the thyroid’s tissue is made up of thyroid follicles, which are central cavities filled with colloids, or sticky fluids. The colloid is where the thyroid produces its hormones, and is gated by a wall of epithelial follicle cells.
Though the thyroid’s anatomy seems quite simple, its function is important: it produces a set of hormones that are instrumental in metabolism, protein synthesis, and tissue growth as well as development when we’re children.
Our basal metabolic rate (aka how much energy we use when at rest) is influenced by two hormones produced by the thyroid: T3 and T4. Because of this, they are frequently referred to as the “metabolic hormones.” Additionally, we need sufficient amounts of T3 and T4 in order to successfully assemble proteins, as well as to develop and grow tissues from when we’re in fetal development through childhood. T3 and T4 are, in fact, especially important in the healthy development of our nervous system; the hormones continue to support our nervous system’s function in adulthood.
T3 and T4 also have complicated relationships with our reproductive hormones. As a result, imbalances in T3 and T4 could have a profound impact on our sex drive, fertility, and other reproductive behaviors. Excessive levels of T3 and T4 speed up our heart rate and increase our blood pressure, as well as strengthen the heartbeat.