On the surface of the thyroid gland there are 2 pairs of very small oval parathyroid glands. It contains two types of cells. Principal cells and oxyphil cells. Its weight is 140 mg. Parathyroid hormone or parathormone parathyrin is released from this gland. It increases calcium levels and decreases phosphate levels in the body. It activates vitamin-D. Vitamin-D deficiency causes rickets in children and osteomalacia in adults.

It regulates metabolism, heart rate, protein synthesis, fetal development, sensitivity etc.

It regulates calcium levels in the body, phosphate metabolism and vitamin-U production.

95% of the hormones released from the thyroid gland are thyroxine hormones. This hormone regulates body metabolism and growth. Helps in the expression of sexual symptoms. Increases heart function. Increases milk production.

The two dark red lumps on either side of the trachea are called thyroid glands. Female thyroid gland is more prominent than male. Its weight is 20-25 grams. Three active hormones are secreted from this gland.
(i) Thyroxine hormone (Thyroxine-T4): 95% of the hormones released from the thyroid gland are thyroxine hormones. This hormone regulates body metabolism and growth. Helps in the expression of sexual symptoms. Increases heart function. Increases milk production.
(ii) Calcitosine: It regulates calcium levels in the body, phosphate metabolism and vitamin-U production.
(iii) Tri-iodothyronine-T3 : It regulates metabolism, heart rate, protein synthesis, fetal development, sensitivity etc.

Gonadrotropic hormone. It helps in growth of genitals.

Vasopressin Hormone. It regulates the amount of water in urine.

It accelerates uterine muscle contraction during childbirth. Helps in secretion of milk from mammary glands.

Somatotropic hormone. It regulates body growth.

Adrenal stimulating hormone. It regulates the secretion of adrenal cortex.