Thyroxin (sometimes written "thyroxine") is a hormone sectreted by the thyroid gland, which is an endocrine gland in the human body - see the diagram of the locations in the body of the endocrine glands.
Functions of thyroxin :
Thyroxin is important for the regulation of the body's Basal Metabolic Rate (BMR), which is the amount of energy the body uses, just to ‘tick over’.
The consequences of both excessive quantities of thyroxin in the body (hyper-thyrodism), and insufficient thyroxin in the body (hypo-thyroidism), are summarised below:
Hyper-Thyroidism = ‘over-active thyroid’ = Thyrotoxicosis
- increase in BMR
- increase in heart-rate
- loss of weight
- develops bulging eyes due to accumulation of fluid behind the eye
- may develop Goitre
- possible link with Attention Deficit Disorder (speculation).
- decrease in BMR
- weight gain
- skin becomes dry and puffy
- hair becomes thin and brittle.
Can lead to:
- Derbyshire Neck (originally due to insufficient iodine in the soil in Derbyshire),
- Graves Disease, and
- Cretinism (= metal and sexual development imapaired, if occurs in children).
See also: What is a Hormone ?
For further general information including the locations of the endocrine glands, see the Endocrine Glands of the Human Body.
- Introduction to the Endocrine System
- What is a hormone ?
- Water Soluble Hormones vs Fat Soluble Hormones
- Triggers for Hormone Release
- Hormone Regulation Feedback Mechanism
- Major Glands of the Endocrine System
- The Pituitary Gland
- The Adrenal Glands
- Non-endocrine tissues that release hormones
- Conditions of the Endocrine System