thyroid gland
Think of the thyroid as your body’s thermostat and pace-setter. It is a soft, butterfly-shaped gland wrapped around the front of your windpipe, just below the Adam’s apple, and the hormones it releases tell nearly every cell how fast to burn fuel and run its housekeeping.
The thyroid takes up iodine from the diet and uses it to build two iodine-containing hormones, thyroxine and triiodothyronine. These hormones travel through the blood and raise the basal metabolic rate, generate body heat, and are essential for normal brain development in the fetus and infant. The gland’s output is controlled by thyroid-stimulating hormone from the pituitary, which in turn responds to thyrotropin-releasing hormone from the hypothalamus, all held in balance by negative feedback.
Because thyroid hormone touches so many tissues, both too much and too little produce wide-ranging symptoms — from heart rate and weight to mood, bowel habit, and skin. The thyroid also contains scattered C cells that make calcitonin, a separate hormone involved in calcium handling, so the gland is not concerned with metabolism alone.
A clinician checking a patient’s thyroid asks them to swallow while palpating the neck; the gland rises with the swallow because it is attached to the windpipe, helping distinguish it from other neck lumps.
A bedside maneuver that uses the thyroid’s anatomy to identify it.
The thyroid is one of the most vascular organs in the body relative to its size, which is why thyroid surgery demands great care with blood vessels.