An earlier Insight discussed the body as the overlapping operations of three different machines—biochemical, physical, and computational. Let’s take a look at that description to help us better understand the vital operation of the thyroid.
The basic function of the thyroid is well known: as a gland, it produces hormones that regulate many body functions, and particularly functions related to energy. (A small set of glands that are embedded within the thyroid, called the parathyroid, produces a hormone that control calcium levels—which is critically important, but not our focus here.)
The thyroid may produce and release hormones that increase the force with which your heart contracts, increasing blood flow. The increased blood flow supplies additional oxygen to the cells, carries away the additional waste products and transfers the heat that is generated.
The thyroid hormone also increases the rate at which your liver converts protein and fat components to glucose and the rate at which fat molecules are broken up into elements that can be oxidized (fatty acids) or converted to glucose (glycerol).
That covers the biochemical and physical machines. Let’s talk about computation. What causes the thyroid to produce and release more hormones, or less? That is controlled by a part of the brain called the hypothalamus, found in the lower center area of the brain. The hypothalamus receives information from the nervous system, including the state of various substances in the blood such as glucose and insulin, as well as body temperature. The hypothalamus is also known to be influenced by one’s emotions. Depending on these and other inputs, it may or may not issue hormonal instructions to the pituitary gland to either generate or withhold yet another hormone that stimulates the thyroid to produce and release its own activating hormones.
It looks like this:
There’s a lot more one could learn about the thyroid and hypothalamus, but the big picture shown above illustrates three aspects of the control of ALL body systems:
- Hormones that regulate chemical and physical changes are activated due to
- computations made in the nervous system based on
- information about the state of the body.
