Your thyroid is a small gland located in the front of your neck just below the voice box and above the collar bone. There are two portions to the thyroid gland, called lobes, with one on either side of your windpipe. The thyroid secretes thyroxine and triiodothyronine, and these hormones regulate the rate of your metabolism--the chemical processes occurring in cells throughout your body. The thyroid hormones influence the functioning of all the organs in your body.
Metabolism Defined
The life-sustaining processes that go on in the cells of your body are referred to as metabolism, and it comprises two separate parts. One of these is called anabolism, which means the building of large, complex substances from simpler, smaller substances. Anabolism consumes energy from the cell. An example is the assembly of proteins from single amino acids. Catabolism is the other part of metabolism, and it involves the breaking down of complex molecules into simpler ones. Catabolism gives off energy to the cell, and an example is the breakdown of carbohydrates into glucose, according to Medical News Today.
Effect on Lipid Metabolism
According to Professor Richard Bowen of Colorado State University, your thyroid hormones play a part in the metabolism of lipids, also called fats, because they stimulate the process of fat mobilization. Fat in the body resides in fat cells in the form of triglycerides, fatty acids bonded to glycerol. Fat mobilization means the triglycerides are broken down into free fatty acids which can then enter the bloodstream and travel to cells such as muscle cells that need energy. In a process of catabolism promoted by the thyroid hormones, the muscle cells oxidize the fatty acids and use the energy given off in the oxidation.
Effect on Carbohydrate Metabolism
Your body, particularly liver and muscle cells, stores glucose in the form of a large, complex molecule called glycogen. When glucose is needed for energy, the thyroid hormones take part in a process called glycogenolysis, which is the catabolic breakdown of glycogen into glucose. In addition, thyroid hormones stimulate gluconeogenesis, the synthesis of glucose from amino acids or other non-carbohydrate materials. Thyroid hormones also participate in the process whereby insulin ushers glucose from the blood into various types of cells in the body.
Cardiac Effects
Thyroid hormones influence the metabolism of heart muscle cells, and this influence shows up in your heart rate and heart function, according to Dr. Ramaswami Nalini of the Baylor College of Medicine. If your thyroid gland is not producing enough thyroid hormone, a condition called hypothyroidism, your heart rate will be too slow and your doctor may treat you by administering thyroid hormone to bring you to the right level. If you are producing too much thyroid hormone, known as hyperthyroidism, you may have shortness of breath and a rapid heart rate.
References
- University of Maryland Medical Center; Endocrinology Health Guide: The Thyroid Gland; August 2010
- Medical News Today; What is Metabolism? How Do Anabolism and Catabolism Affect Body Weight?; Christian Nordqvist; August 2009
- Colorado State University; Mechanism of Action and Physiological Effects of Thyroid Hormones; Richard Bowen; July 2010
- Baylor College of Medicine; Thyroid Problems Often Overlooked; Dipali Pathak; January 2010
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