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

What ions must a plant obtain from the soil in order to make (a) ATP, (b) chlorophyll?   (a) To create ATP (adenosine triphosphate) a plant requires a supply of phosphate io

Determine some assessment measures of Zinc? Measurement of zinc in plasma: This is the most common method. Fasting concentrations of less than 70 μg/litre suggests deficie

How does the synthetic theory of evolution incorporate knowledge from Genetics and Molecular Biology into the darwinism? Today it is known as that variation of inherited charac

In vitro Studies - Nutrition of Embryo Studies involving culture of embryos excised of various stages of development (i.e., early globular proembryo, late globular proembryo o

Intravenous Route This route of administering drugs is becoming more popular in the paediatric practice. Purpose of this Route When rapid action is required.

DIVERGENC E - In it blastomeres move in different directions i.e. inside the blastocoel the blastomeres move in different directions. The blastomeres which move inside i

Non-threshold  approaches For  genetic carcinogenes, the  "NOEL-safety factor"  approach  is generally  not considered a suitable method for setting the acceptable intake level


Q. Why is it said that during photosynthesis carbon dioxide is improved to form glucose? During photosynthesis carbon dioxide is energetically improve with hydrogen from water.