Thyroid gland , Diseases of thyroid gland & Function of Parathyroid glands
Thyroid gland lies in the anterior part of neck and in a close contact with the trachea , Its colour is slightly red , It is surrounded by a membrane of connective tissue , It consists of two lobes that are connected together by an isthmus , the thyroid gland secretes two important hormones which are thyroxine hormone and calcitonin hormone .
Thyroxine hormone ( iodine element is essential for its formation ) that has many effects on different parts of the body such as :
- It affects and stimulates the physical and mental growth .
- It affects and controls the main metabolic rate .
- It increases the absorbtion of carbohydrates ( monosacchrides ) from the intestine .
- It maintains the skin and hair healthy .
Calcitonin hormone which decreases the calcium level in the blood and it prevents the withdrawal of calcium from the bones .
Diseases of thyroid gland : The diseases are caused due to the increase or decrease in the secretion of thyroxine hormone such as goiter and there are two types of this diseases which are :
- Simple goiter which arises due to the hyposecretion of thyroxine hormone .
- Exophthalmic goiter which arises due to the hypersecretion of thyroxine hormone .
Causes : hyposecretion of thyroxine hormone , due to the deficiency of iodine in food , water and air .
Treatment : addition of iodine to salt and different food .
Complications that result from the severe hyposecretion of thyroxine hormone :
Causes : acute hyposecretion of thyroxine hormone during childhood .
- Physical growth : large head , short stature and short neck .
- Mental growth : it may cause a permanent mental retardation .
- Sexual maturity : it may cause a delay in the sexual maturity .
Causes : acute hyposecretion of thyroxine hormone in adults .
- Skin dryness and loss of hair .
- Weight gain and obesity .
- Decreasing the main metabolic rate that causes cold intolerance .
- Decreasing the heartbeats and rapid fatigability .
Treatment : by using thyroid gland hormones or its extracts under the supervision and regular consultation of a specialist .
Causes : hypersecretion of thyroxine hormone .
- Noticed enlargement of the thyroid gland and anterior part of the neck with protrusion of the eye balls .
- Increase in the food oxidation and metabolic rate .
- Increase in the heartbeats .
- Loss of weight and nervous irritability .
Treatment is either by surgical removal of a part of the thyroid gland or using other medications to suppress the gland .
It consists of four small separate lobes , where each two of them are located on each side of the thyroid gland and it secretes parathormone hormone :
Function of parathormone hormone :
- It plays an important role with calcitonin hormone ( secreted from thyroid gland ) in preserving the normal calcium level in blood .
- Amount of parathormone hormone depends on the calcium level in the blood , where its secretion increases , when the calcium level in blood decreases .
Hypersecretion of parathormone hormone ( Hyperparathyroidism ) leads to increasing the calcium level in the blood , as most of the calcium is released from the bones which leads to bone resorption and the bones become fragile and liable for bending and fracture .
Hyposecretion of parathormone hormone ( Hypoparathyroidism ) leads to :
- Decreasing the calcium level in the blood .
- Painful convulsions and muscle spasm .
- Increasing the excitability of nervous system .