The effects of T 3 on target cells increase the oxygen consumption and heat production in the cell, accounting for the calorigenic effect. This effect is stimulated by cold weather and pregnancy. This results in skeletal system stunting, thickened facial features, low body temperature, and mental retardation. Adult hypothyroidism causes myxedema, a condition characterized by low metabolic rate, weight gain, elevated blood pressure, sluggishness, and other symptoms. A goiter is a pathological enlargement of the thyroid gland.
Endemic goiter is due to dietary iodine insufficiency.
PTH raises blood levels of calcium by promoting its absorption through the intestines, by inhibiting urinary excretion of calcium, and by increasing osteoclast activity. Hyperparathyroidism elevates plasma levels of calcium and phosphate ions, softens bones, and causes kidney stones to develop. Their effects mimic those of the sympathetic nervous system but last longer because they are secreted into the bloodstream. The pancreas is located retroperitoneally, below and behind the stomach. Pancreatic Hormones Insulin, from beta cells, is secreted in response to rising blood levels of glucose and other nutrients.