Complete Overview of Thyroid Gland


The thyroid gland is one of the vital glands in the endocrine system of our body. The endocrine system produces hormones. Endocrine system comprises eight major glands. We are well aware that the glands of the endocrine system are ductless, well, even the thyroid gland falls into that order. The meaning of ductless glands or the thyroid gland definition is that they secrete their product i.e, hormones directly into the bloodstream instead of using ducts to secrete the hormones. The secretion from thyroid gland helps in the regulation of growth and development of the human body. This piece of information on the thyroid gland must be highly valued. 

Thyroid Gland Structure

The thyroid gland is generally bilobed in mammals. It closely resembles a butterfly in its appearance. Since it is bilobed, the lobes are divided into left and right. But ultimately connected by a small bridge-like structure known as Isthmus. Each lobe is about 5 cm long, 3 cm width and 2 cm thick. And the complete thyroid gland weighs a mere 25 grams in a grown adult. (if it is healthy, of course!) It measures around 2 inches in length, which is approximately equal to 5.08cm. The thyroid gland is sheathed with a thin fibrous capsule which has two layers. And there are small structures known as Parathyroid glands embedded in the back of the thyroid gland between these two layers.

  • The Dimensions of the thyroid gland are a bit larger in women than in men, and also you can spot a substantial increase in the size of the thyroid gland in pregnant women.

Thyroid gland Location

Let’s delve into the question of Where is the thyroid gland located? The answer to this question is as follows. The thyroid gland is located or it can be seen in the front of our neck or head region. Ok, maybe we can’t see without tearing down the throat skin. It usually covers the frontal part of the larynx and trachea (windpipe). It lies just below Adam’s apple in your throat region. Even if you try to find the gland you will be not successful when it is in normal size.

But when you are ridden with any one of those Thyroid related disorders, the difference is explicitly visible. This gland shares its space, in the visceral compartment of the neck with trachea, esophagus, and larynx. During the initial stages of the human development, it is present near the base of the tongue; but it gradually descends as we grow into adulthood and settles near the trachea.

Thyroid Gland Functions

The primary function of thyroid gland is to secrete hormones, store them and release them at the times deemed necessary. This particular gland is in fact supplied by the bundles of nerves from the sympathetic trunk, but like a headstrong fellow, it is not used to follow orders from the nervous system. The pituitary hormone that triggers the release of thyroid hormone from the thyroid gland is It directly reports to the pituitary hormone that triggers the release of thyroid hormone from the thyroid gland is Thyroid stimulating hormone (TSH) when it comes to the orders of secretion of hormones. TSH regulation is stimulated by the Thyrotropin-Releasing Hormone(TRH) released by the hypothalamus.

Thyroid Gland

Now, you are wondering what hormones does the thyroid gland produce, making the function of the thyroid gland sound so important Right? The thyroid gland secretes mainly two hormones namely:

  • T3 (Triiodothyronine)
  • T4 (Thyroxine)

This gland also secretes calcitonin, a peptide hormone. Normal thyroid functioning is of utmost importance for a healthy body. To determine the condition of normal thyroid functioning, the first step is the production of T3 and T4 in normal levels.

[Also See] Normal TSH levels and Optimal TSH levels in the Body

About the Thyroid Hormones

The hormones are prepared from the food you eat. Yes, they are indeed and it is true. Only the thyroid gland can absorb the iodine from our food. The iodine present in the foods is useful in the formation of the two main hormones namely Thyroxine and Triiodothyronine. T3 and T4 are chemically created form the hydrophobic tyrosine amino acid and iodine, a chemical element. Tyrosine is one of the 20 standard amino acids. The ratio of T3 is to T4 in the total released hormone in a healthy human being is 20:80. These three hormones are created from the thyroglobulin, a protein with 123 units of tyrosine in its structure.

The production is stopped as soon as the body’s requirement if the T3 hormone is fulfilled, through a negative feedback mechanism. No sooner the hormones are released, they are automatically bound to the carrier protein molecules, but some of it remains free in the bloodstream. And this percent of free-floating thyroid hormone is known as free or total thyroid hormone. The next time you see your thyroid reports you are bound to get a clear picture about the functioning of your thyroid gland. 

Quick Q/A: How is Iodide brought into follicular cells from the bloodstream in the thyroid gland?

Through Sodium/iodide symporter. 

T3 Hormone

The T3 hormone is the prominent one of the thyroid gland hormones in regulating the healthy operation of our body. Triiodothyronine is the alternative name of the T3 hormone. The chemical formula of T3 hormone is C15H12I3NO4. Triiodothyronine is basically the active counterpart of thyroxine. The production of T3 effects almost all the cells in every nook of our body. The functions of T3 is to regulate the:

  • Body’s metabolic rate
  • Brain development and function
  • Heart and digestive functions
  • Muscle control
  • The maintenance of bones

thyroid gland

T4 Hormone

The main purpose of the T4 or Thyroxine hormone is nothing but the conversion of it into the useful and active form of the T3 hormone. T3 is almost the same as T4, except with a minor difference that is the T4 has an extra molecule of Iodine. This extra molecule of iodine causes it to be in its inactive form. So, it obviously needs to be converted into T3 which usually takes place in the liver. But it is equally likely for the conversion to take place in the cells of heart, stomach, muscles, and nerves. Now, for proper functioning liver needs to be in a good condition if it is needed to convert the T4 into T3 and convert into the active state.

thyroid gland

[Check More] Normal Thyroid Hormone Levels in Humans


Calcitonin is also a hormone produced by the parafollicular cells of the thyroid gland. The parafollicular cells of the thyroid gland are commonly known as C-cells. The c cells of the thyroid gland produce this particular hormone which helps in Lowering the calcium levels in the blood when it reaches peaks. Not only that, this calcitonin also helps in the bone building process. Furthermore, this hormone opposes the effects of the parathyroid gland, whose sole aim is to increase the calcium levels.

Thyroid Gland Problems

The normal levels of thyroid hormone are to be maintained unless you want to face the wrath of complicated thyroid gland diseases related to the thyroid gland. Hormones play a vital in the smooth functioning of our body. The problems related to thyroid defect are many.

The main thyroid gland disorders that arise with the malfunction of the thyroid gland are:

  • Hypothyroidism
  • Hyperthyroidism

However, there are certain other complications too apart from the above two thyroid gland problems like Four common disorders of the thyroid are Graves’ disease, Hashimoto’s disease, goiter, and the nodule on thyroid gland etc.

[Know More] Best Exercise Plan and Yoga Asanas for Thyroid Problem


Hypothyroidism defines the condition of the underactive thyroid gland. Due to this, the amount of thyroid hormone which is to be produced for the smooth working of our body is declined or decreased. The lower levels of the hormones mean changes in heart rate, body temperature and all aspects of metabolism. In addition to that, this change in metabolic rate boosts the unexpected weight gain. This condition often visits the aged women. 

[ALSO CHECK] What is Hypothyroidism- Causes, Symptoms, & Diet


Hyperthyroidism relates to the overactive thyroid gland which leads to the enlargement of the thyroid gland also known as goiter. Overactive thyroid gland means an excess of production of thyroid hormone, mainly T4 or thyroxine. Contradictory to the hypothyroidism, the patients suffering from hyperthyroidism suffer unexpected and unexplained weight loss. Also, Apart from the weight loss one of the most prominent slow thyroid gland symptoms is a swollen thyroid gland or an enlarged thyroid gland.

[READ MORE] Information about What is Hyperthyroidism?

To know about the thyroid problems in detail please visit My Thyroid Problems. Don’t forget to check the info regarding the TSH Range levels and the Thyroid Treatments available medically.