|
|
Article: Thyroid Gland
- Article from:
- Biology
- Author:
CopyrightCOPYRIGHT 2002 The Gale Group Inc. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
|
Thyroid Gland
The thyroid gland, the largest of the
endocrine
glands, is located in the neck just below the thyroid cartilage of the
larynx
. It consists of two lobes, one on either side of the trachea, joined by a narrow band or isthmus. It is composed of numerous hollow ball-shaped follicles with small, interspersed clusters of parafollicular cells.
Follicle cells concentrate and attach iodine to the
amino acid
tyrosine, producing two forms of thyroid
hormone
(TH): thyroxine or tetraiodothyronine (T
4
), and smaller amounts of triiodothyronine (T
3
). Manufacture and release of these hormones into the blood is regulated by thyroid stimulating hormone, TSH, from the pituitary gland. ...