Thyroid Gland - Thyroxine and Calcitonin

Thyroid Gland is responsible for secreting and produce the hormones responsible for our metabolism rate. One of these hormones is called thyroxine (T4).
The thyroxine will increase the rate of metabolism of  fats, proteins and carbohydrates for energy. It stimulates the cells of several tissues through out the body. It also play an important role in the growth and development of children.

Disorders

If the thyroid fails to develop properly during childhood, the children will develop a condition called cretinism which will result in shorter individual with metal problems. Other condition called hypothyroidism is caused by the insufficient   production of thyroxine. Over production will lead to hyperthyroidism which will lead the individual to weight loss, heat intolerance, and irregular heart beat. Graves'disease is a severe state of hyperthyroidism that is result from the immune system attacking the thyroid gland.
The thyroxine production is controlled by a negative feedback loop. The anterior pituitary gland release the TSH which will cause the thyroid gland to secrete thyroxine. The thing is that thyroxine needs iodine to be produced. If there is no iodine, thyroxine level in the blood will never be reaches, therefore TSH will always be produced, generating the condition called goitre.

Calcitonin

Calcitonin is essential hormone used to control the calcium concentration in the blood. If it is to high, it will stimulates the bones to not release calcium and the kidney to not reabsorb calcium form urine.