Question

Name hormones secreted by the Thyroid gland and specify one function

Answer 1

The thyroid gland is the largest endocrine gland which releases three types of hormones released by the follicular cell and the parafollicular cells of the thyroid gland. The two hormones are in the iodinated form whereas the third hormone is responsible for the calcium in the blood plasma.

Complete Step by Step Answer: Follicles and stromal tissues are made of the thyroid gland. The follicular cells that make up the follicles, synthesize two hormones, namely, Tetraiodothyronine or Thyroxine (${ T }_{ 4 }$) and triiodothyronine (${ T }_{ 3 }$). The parafollicular cells release calcitonin (TCT).
Tetraiodothyronine or Thyroxine (${ T }_{ 4 }$) and triiodothyronine (${ T }_{ 3 }$) are the iodinated forms of an amino acid called tyrosine and remain stored in the jelly-like semifluid material (colloid) in the lumen of the follicles.
The parafollicular or the C-cells are present in between the thyroid follicles which secrete Calcitonin (TCT) or parafollicular hormone. It is involved in calcium homeostasis. It is hypercalcemia or hypophosphatemic.

Additional Information: There are two associated lobes of the thyroid or thyroid gland in the neck. It is shaped like a butterfly or it is H-shaped. A thin band of tissue called the thyroid isthmus binds the lower two-thirds of the lobes.
Functions of thyroid hormones: - They control the metabolism of proteins, fats, and carbohydrates, hence regulate the growth of the body tissue. -These hormones regulate basal metabolic rate (BMR). - It enhances the actions of neurotransmitters like adrenaline, and nor-adrenaline. - Maintenance of water-electrolyte balance.
The deficiency of thyroid hormone causes Hypothyroidism. Excess of thyroid hormone causes hyperthyroidism.

Note: - ${ T }_{ 4 }$ contains four atoms of iodine and ${ T }_{ 3 }$ is secreted in small amounts but is more active and several times more potent than ${ T }_{ 4 }$, hence, ${ T }_{ 4 }$ is converted to ${ T }_{ 3 }$ by removal of one iodine atom in the liver, kidneys and some other tissues. - Thyroid is the only endocrine gland that stores its secretory products in large quantities also involved in iodine metabolism. - Since, Tetraiodothyronine or Thyroxine (${ T }_{ 4 }$) and triiodothyronine (${ T }_{ 3 }$) have similar effects on target cells they together are known as Thyroid Hormone (TH). - These hormones are not released on their own rather are released under the control of Thyroid Stimulating Hormone (TSH) released from the anterior pituitary.