What Are Hormones?

They are types of chemical that the body uses to send a signal from one body part to another. A hormone might be made in the brain, released into the blood and travel to some distant organ, such as the kidney. When it reaches the kidney, this chemical will usually trigger some effect. Hormones are powerful. It takes only a tiny amount to cause big changes in cells or even the whole body. That is why too much, or too little of a certain hormone can be serious.

Below are some activities that bodily hormones are responsible for:

  • Growth and development
  • Metabolism – how your body gets energy from the foods you eat
  • Sexual function and reproduction
  • Mood
  • Maintenance of body temperature and thirst

Where Are They Secreted From?

A body showing the endocrine glands, and their respective positions

A body showing the endocrine glands, and their respective positions

Hormones are secreted from the endocrine glands in the body, and they are secreted directly into the blood stream. In addition, men produce hormones in their testes and women produce them in their ovaries. Some of the major endocrine glands in the body include:

  • Pituitary gland – It is found at the base of the brain, below the hypothalamus. Two of the hormones it produces are vasopressin – which regulates the volume of water in the kidneys and oxytocin – which stimulates the contraction of the uterus during birth, and the release of milk for suckling . Pituitary gland hormones either act on other glands, stimulating them to produce hormones, or act directly on tissues and organs.
  • Pineal gland – It is found in the brain. It secrets the hormone melatoninwhich regulates our sleep and wake cycles. It is usually produced in high quantities in the dark, especially at night, which is what makes us feel sleepy at night.
  • Thyroid gland: The thyroid gland is located in the front part of the neck, just below the Adam’s apple. With the aid of the pituitary, it produces two hormones; thyroxine (T4) and triiodothyronine (T3) which are responsible for growth and development, and the breaking down of food into energy for use by the body.
  • Thymus – It is located in the chest, in an area in front of the heart. It forms part of the immune system and produces and equips T Cells, also known as lymphocytesthese attack, kill, and remove foreign substances from the body, called antigens.
  • Adrenal glands – They are located at the top of each kidneys. They produce the hormones adrenalin and cortisolwhich prepares the body for stress conditions; noradrenalinwhich increases the rate and depth of breathing; and corticosteroidswhich regulate salt and water balance.
  • Pancreas – These are found in the abdomen, behind the stomach. They produce insulinwhich is responsible for reducing glucose or sugar level in the blood, and allows body cells convert glucose to energy.
  • Testes – These are found in the scrotal sac only in men, and they produce the hormone testosteronewhich is responsible for the development of features like broad shoulders, deep voice, enlargement of the genitalia, and body hair, as well as the production of sperm cells for reproduction.
  • Ovaries – They are found in the lower abdomen only in women, and secrete the hormones oestrogenwhich is responsible for the development of features like breasts, menstrual cycle and wider hips in women, and progesteronewhich prepares the uterus or womb  for pregnancy

These organs secrete hormone in microscopic amounts and it takes only very small amounts to bring about major changes in the body. Even a very slight excess of hormone secretion can lead to disease states, as can the slightest deficiency in a hormone.