Hormones secreted by thyroid gland, Biology

Hormones. The thyroid gland secretes following hormones.

Thyroxine (tetraiodothyronine or T4)' and tri-iodothyronine or T3 are secreted by the thyroid follicular cells.

Calcitonin is secreted by the C-cells of the thyroid gland.

(i) Thyroxine (T4) and Tri-iodothyronine (T3) T4 and T3 contain four and three atoms of iodine.

T3 is secreted in smaller amounts (10%) but it is more active and several times more potent than T4

T is converted into Tby removal of one iodine in the liver, kidneys and some other tissues.

T4 and T3 have similar effects on the target cells, they are generally considered together under the name, thyroid hormone (TH).

The thyroid gland is the only gland that stores its hormones in large quantity.

T4 and T3 are synthesised by attaching iodine to the aminoacid tyrosine.

Function of T3 & T4  -

(a) They regulate the metabolic rate of the body and thus maintain basal metabolic rate (BMR)

(b) They stimulate protein synthesis and, therefore, promote growth of the body tissues.

(c) They regulate the development of mental faculties.

(d) As they increase heat production, thus they maintain body temperature.

(e) They help in metamorphosis of tadpole into adult frog. If thyroid gland of the tadpole (larva) is removed, the larva fails to change into an adult.

(f) They increase action of neurotransmitters like adrenaline and noradrenaline.

(ii) Calcitonin (CT). It is secreted when calcium level is high in the blood. It then lowers the calcium level by suppressing release of calcium ions from the bones. Thus calcitonin has an action opposite to that of the parathy- roid hormone on calcium metabolism.

Posted Date: 10/2/2012 6:46:35 AM | Location : United States

Related Discussions:- Hormones secreted by thyroid gland, Assignment Help, Ask Question on Hormones secreted by thyroid gland, Get Answer, Expert's Help, Hormones secreted by thyroid gland Discussions

Write discussion on Hormones secreted by thyroid gland
Your posts are moderated
Related Questions

Kidney impairment is one of the long term complications of diabetes mellitus. Measurement and monitoring of kidney function parameters such as urea and creatinine, in addition to u

Development of Nutritional Biochemistry Nutrition,  in  general, and  particularly nutritional biochemistry, has  traveled a  long way since 1926, when nutrition was first reco

Specific Causes of Parental Anxiety   Some of the factors  that increase  their anxiety include following:  1)  Fear of the strange environment in the hospital  2)  Fear

What are the main events of the final mitotic period? The final mitotic phase is telophase. In telophase the following events happens: decondensation of chromosomes, every set

To get the idea on the process capability that whether the intended process provides the consistent results or not(precision).

Q. Explain about Tropical Rain Forests? As you approach the equator the climate becomes increasingly hot and seasonal variation in climate decreases resulting in practically th

Phases of Karyokinesis: Karyokinesis can further be divided into prophase, metaphase, anaphase and telophase. 1-Prophase: (pro= before) Chromatin: During Interphase (non

Q. How Tyndallisation used for sterilization? John Tyndall devised a process of sterilisation by steaming for a few minutes at 100 o C on 3-4 successive operations separated by

Q. What is the essential morphology of a protozoan cell? Protozoans are eukaryotic cells so they have structures and organelles common to this kind of cell endoplasmic reticula