Endo 101: Endocrine-Related Organs

Several organs play a major role in the helping the endocrine system to work well. Although these organs are not glands themselves, they do produce, store and send out the types of hormones that help the body to function properly and maintain a healthy endocrine system.

Placenta

Besides providing a connection between mother and fetus, the placenta is a special endocrine organ. It produces hormones that are similar to those produced elsewhere in the body. Human chorionic gonadotropin (hCG), estrogens and progesterone are among the most important of these, because they maintain a pregnancy and prepare a woman's mammary glands for nursing.

hCG stimulates the ovary to produce estrogens and progestins and helps control normal development of the fetal genitals. The estrogens in the placenta stimulate breast development, promote normal labor, and help produce a steady rise in prolactin. The progestins stimulate breast development and help reduce uterine muscle contractions. Human placental lactogen is a hormone that decreases the mother's level of growth hormone and increases the amount of blood glucose and lipids (fatty substances) circulating in the mother's blood.

Skin, Liver And Kidneys

These three organs work together to synthesize 1,25-diydroxyvitamin D, the active form of vitamin D, which controls levels of calcium and phosphorus in the blood. In the skin, a modified cholesterol (fatty) molecule is converted to vitamin D by chemical changes through ultraviolet rays from the sun. In the liver, vitamin D3 is converted to 25-hydroxyvitamin D (calcidiol) before going to the kidney where it is converted to 1,25-dihydroxyvitamin D3 (calcitriol) with the help of parathyroid hormone. Calcitriol acts on the intestine, kidneys, and bones to maintain normal levels of blood calcium and phosphorus. Too little calcium in the diet can lead to rickets in children and osteoporosis in adults.

Stomach And Small Intestine

The digestive tract is the largest endocrine-related organ system in the body. It makes and secretes several different types of hormones that play a role in the body's metabolism. Gherlin and leptin are two such hormones that have been shown to regulate appetite and may be important in obesity and weight loss.