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
Incompatibility - Pollination and Fertilization Plants growing under natural conditions have a preference for their mating partners. The stigma of the female parent receives a

Signify the term - Pectoral girdle. Bones in vertebrates that connect the appendages on the left and right side of the anterior appendicular skeleton to each other. Pectoral gi

Determine the Syndrome of Listeriosis Syndrome: Listeriosis in humans is not characterized by a unique set of symptoms since the course of the disease depends upon the state

Fibro-osseous Retention V/S Osseointegration Fibro-osseous retention is the tissue to implant contact interposition of the healthy, dense collagenous tissue between the implant

Q. What do you mean by Periodical? A periodical is a publication appearing at regular intervals. Each issue is called a number and collectively these numbers comprise a volume.

Describe Pharmacologic Agents in amyl nitrite ? Amyl Nitrite : It produces vasodilatation which initially results in marked fall in BP and in the next 30-60 seconds there is

Which factors are altered when cells are moved from an in vivo to an in vitro environment, and how do cells respond to these changes?

Q. Etiology of constipation? The etiology and management of two distinct disorders of the bowel viz., diarrhoea and constipation. We small continue our discussion on certain ot

Q. What are the catalysts? Catalysts are substances that decrease the activation energy of a chemical reaction, facilitating it or making it energetically viable. The catalyst

Explain Generation of sound in MVP? Generation of sound in MVP: These are generated due to sudden tensing of redundant leaflets and elongated of chordae tendinae. Interventions