QUESTION FOR THE GENIUS☺☺Quality answer required...Describe about thyroid gland in detail----location,parts,capsule, blood supply,and its histology,,,No copy answer...If you don't know the perfect answer then left it...No useless answer
Answers
-it is made up of two lateral loads and one long is present on either side of the larynx. both letter notes are connected with each other by thin filament structure called isthmus.
-thyroid gland is made up of many spherical bags like structure called follicle all follicles bind Together by connective tissue called stroma it is vascularized in structure.
-follicles are made up of single layer of cuboidal epithelium and it encloses a small lumen is filled with a colloidal solution of hormones.
-there are two types of cells in thyroid gland
* principal cells which are follicular cells of thyroid gland. secret several hormones like thyroxine
* parafollicular cells which is present in stroma between follicles. It secrets calcitonin hormone.
*function of thyroxine hormone
-thyroxine helps in metamorphosis in amphibians animals if larval stage is present throughout the life called neoteny it is sexually mature state
- it causes moulting in reptiles
- it helps in growth of mammalian body by multiplication of cells
- it also controls basal metabolic rate. (more in kids)
- it controls metabolism of proteins fats carbohydrates and Minerals
- also helps in conservation of Vitamin B complex in the body
- and at last it maintains shape and size of heart
* function of calcitonin
-it controls of optimum level of calcium in the blood.
* diseases
:in hypo secretion of thyroxin
- cretinism and it occurs in child as it is characterized by retardation of mental and physical growth
- myscodema it occurs in adults only and it is characterized by swelling of body increase weight increase in Heartbeat and impotency.
- simple goitre it is characterized by enlargement of thyroid gland
:in hyper secretion of thyroxin
- exophthalmic goitre popularly known as graves goitre in this eyeball became large and protuided from eyes Orbit, enlargement of thyroid gland and increase in body temperature
The Human endocrine system has the presence of thyroid gland.
Location, structure, histology and origin:
The thyroid gland is originated and devloped from the endoderm of the embryo.
The thyroid gland I said the largest endocrine gland present in the body which is located at the anterior region to the thyroid cartilage of the larynx (voice box) in the meck. The gland is well supplied with blood vessels connected to it. It is a bilobed or a bilobular organ. The two lobes are now connected by a narrow structure called the isthmus. The microscopic structure of the thyroid gland shows they have thyroid follicles composed of cubical epithelium and filled with a homogenous material called colloid. Small amounts of loose connective tissue are also present which collectively form Stroma of the gland.
Besides containing blood capillaries, the Stroma contains small clusters of specialized highly functional "parafollicular cells" or "C cells". The thyroid gland is the only gland that has some stored hormones in large quantities for about two months to be specific.
Hormones: The thyroid gland secretes three main hormones. Thyroxine (tetraiodothyronine or T4) and tri-iodothyronine or T3 which are secreted by the thyroid follicular cells. Thyrocalcitonin is secreted primarily by the C cells or the parafollicular cells of the thyroid gland. This gland is particularly stimulated to secrete its horizons by thyroid stimulating hormone (also called or known as thyrotropin) which are secreted by the anterior lobe of the pituitary glamd.
1) Thyroxine (or T4) and Tri-iodothyronine (or T3): T4 and T3 contain about four and three atoms of iodine respectively, therefore, they are named so because of it. T3 is secreted in very small amounts or smaller amounts but it is more active and several times more potent than T4. T4 is converted into T3 by the actual removal of one iodine in the liver, kidneys and some other major and minor tissues. Since both T4 and T3 have similar effects on their target cells, they are generally considered together under the specific name of, thyroid hormone (TH).
The thyroid gland Is the only gland That stores its own hormones in a larger than required quantity . T4 and T3 are further synthesized by attaching iodine to tyrosine (tyrosine is an aminoacid which forms thyroxine, nonadrenaline and adrenaline hormones) aminoacid. The function of thyroxine (T4) and tri-iodothyronine (T3) are as given, under the points:
A) They are regulating the metabolic rate of the body and thus maintain the required basal metabolic rate (BMR).
B) They are stimulators when it comes to protein synthesis and, therefore, promote the growth of bodily tissues.
C) They regulate the development of mental faculties (making the humans mentally stable).
D) As they are increasing continuously, the heat production of the body, thus, they maintain a stable body temperature.
E) They are also helpful in metamorphosis of tadpoles into an adult frog. If thyroid gland of the tadpole or the larvae has been removed, the larvae just fails to change or transform into an adult frog.
F) They are capable of increasing the action of neurotransmitters like adrenaline and nonadrenaline which is crucial for fright, flight and fight development and to react in the environmental conditions.
2) Thyrocalcitonin (TCT): It is primarily secreted when the calcium level is abnormally high in the blood. It then lowers the calcium level by suppressing the release of its calcium ions from the bone. Thus calcitonin hasn't an action opposite to that of the parathyroid hormone on the metabolism of calcium ions. Calcitonin is a peptide which contains about 32 amino acids.