Thyroid hormone is vital hormone that is produced by the thyroid gland present in the neck. There are basically two types of thyroid hormones that are produced but there functions are the same. Thyroid hormone has effects on almost every part of the body. From the contractility of the heart to metabolic functions of the cell, thyroid hormones have effect over every aspect. Thyroid hormones increase the metabolic processes that are going on in the body on a cellular level. Carbohydrates, fats and proteins are all used up by the body in order to produce more cells and hence growth occurs. The contractility of the heart increase and a larger amount of blood reaches various organs in a shorter amount of time. The release of the neurotransmitters and the conduction of the neurons also increase that help in boosting memory and concentration span. Weight of the person, stays within a normal range according to age due to increased metabolic rate. All in all, thyroid hormones play a vital role in the development of the human body