The thyroid gland, or simply the thyroid, in vertebrate anatomy, is one of the largest endocrine glands and consists of two connected lobes. The thyroid gland is found in the neck, below the thyroid cartilage. The thyroid gland controls how quickly the body uses energy, makes proteins, and controls how sensitive the body is to other hormones.
The thyroid gland regulates how the body uses energy for activity or fat storage via thyroid hormones triiodothyronine (T3) and thyroxine (T4), at least in part through interactions with the immune system. These thyroid hormones regulate the bodyâs metabolism, thermodynamics, and haemodynamics. Levels of T3 and T4 are controlled by thyroid stimulating hormone (TSH) released by the pituitary gland in response to thyrotropin releasing hormone (TRH) produced in the hypothalamus. Together these hormones also regulate brain growth and rate of function of many different body systems.
Abnormally decreased thyroid activity, or hypothyroidism, is characterized by an underproduction of hormones T3 and T4. Consequently, the low levels of thyroid hormones fail to meet the metabolic needs of the body. Symptoms of hypothyroidism include weight gain, lethargy, slow cognition, depression, menstrual irregularity, dry skin, and hair loss or baldness. Hypothyroidism is more common in women than men and its prevalence increases after 45 years of age. Hypothyroidism may also lead to congestive heart failure due to the increased systemic vascular resistance and decreased cardiac contractility. Autoimmune thyroiditis or Gravesâs disease treatments in humans are leading causes of hypothyroidism in the elderly. To clinically detect hypothyroidism, it is recommended to test free T4 levels.
A journal is a periodical publication intended to further progress of science, usually by reporting new research. Most journals are highly specialized, although some of the oldest journals publish articles, reviews, editorials, short communications, letters, and scientific papers across a wide range of scientific fields. Journals contain articles that peer reviewed, in an attempt to ensure that articles meet the journal's standards of quality, and scientific validity. Each such journal article becomes part of the permanent scientific record.
Last date updated on July, 2014