Released directly into the bloodstream by organs known as endocrine glands, hormones circulate through the body until they make contact with their target areas.

The initial contact a hormone makes with a cell starts a series of important reactions carried out within that specific cell or tissue.

Some of the activities of hormones include:

  • Prompting cell or tissue growth and development
  • Helping with food metabolism
  • Initiating and maintaining sexual development and reproduction
  • Maintaining body temperature
  • Controlling thirst
  • Regulating mood and cognitive functioning

Humans, animals, and plants all produce hormones that play important roles in helping these organisms function properly.

Glands and Hormones

The following are examples of endocrine glands and some of the hormones they produce.

Pineal gland: Located near the back of the skull, this gland produces melatonin in response to darkness, which encourages sleep.

Pancreas: This organ plays a major role in regulating blood glucose levels by producing the hormones insulin, amylin, and glucagon.

Pituitary gland: Nicknamed the “master gland,” this pea-size gland is located at the base of the brain.

Hormones produced by the pituitary gland include:

  • Growth hormone (GH), which influences development and cell production
  • Prolactin, which stimulates milk production in breastfeeding women and has wide-ranging effects on behavior, reproduction, and the immune system
  • Follicle-stimulating hormone (FSH), which regulates egg release in ovaries and sperm production in testes
  • Luteinizing hormone (LH), which regulates the female menstrual cycle and works with FSH to produce sperm in men

Testes: Best known for producing testosterone (the “male hormone”), the testes actually release several different hormones, including estrogen (the “female hormone”).

Testosterone is responsible for sex drive in men and women, encouraging oil production in the skin, increasing bone mass, and male characteristics such as facial hair, deepening of the voice, and the development of male genitalia during pregnancy.

Ovaries: These organs produce estrogen, which helps regulate reproduction and is responsible for characteristically female traits such as breast development and increased fat stores.

The ovaries also produce progesterone (the “pregnancy hormone”), which regulates both the menstrual cycle and the stages of pregnancy.

Liver: Among its many functions, the liver releases insulin-like growth factor 1 (IGF-1), a hormone involved in cell growth.

Scientists are studying how IGF-1 may be linked to cancer and the aging process.

Hormone Imbalances

Age, genetic disorders, diseases, exposure to environmental toxins, and even disruption of your body’s natural rhythm (circadian rhythm) can harm the body’s ability to produce hormones in the exact amount needed.

Over- or underproduction of hormones can cause serious health problems.

Examples of hormone-related treatments include:

  • Hormone replacement therapy (HRT) for a woman who has either entered or finished menopause
  • Thyroid replacement drugs such as Levoxyl or Synthroid (levothyroxine) to treat an underactive thyroid (hypothyroidism)
  • Cytomel (liothyronine) to help shrink tissue in an overactive thyroid (hyperthyroidism)
  • Testosterone injections for a man with a greatly diminished sex drive, or a genetic sexual disorder like Klinefelter syndrome
  • Melatonin supplements to help initiate asleep while traveling across time zones
  • Zemplar (paricalcitol) to manage overactive parathyroid (hyperparathyroidism) caused by kidney failure