The human body has two types of glands: exocrine glands that secrete fluids into a duct or a tube, and endocrine glands that release chemicals known as hormones into general circulation. Endocrine glands include the pituitary, pineal, thyroid, parathyroids, thymus, pancreas, adrenals and sex glands (ovaries and testes). The hormones they release regulate basic drives and emotions while promoting growth and sexual identity and controlling body temperature. They also help to repair broken tissue and generate energy.
The amount of hormones released by the endocrine glands depends on the body’s needs. Levels change in response to infection, stress and changes in the chemical composition of the blood. Hormones are regulated by control mechanisms within the body. The process is something like this: an endocrine gland secretes its hormone and then the hormone travels to receptors on cells located within a particular tissue or organ. The tissue or organ is then able to carry out its function. However, when the level or activity of the tissue or organ becomes too high, there is a “negative feedback” to the gland that tells it to cut back on production and secretion of this hormone.
Factors in Glandular Health
The endocrine system functions best when it has ample stores of minerals – particularly trace minerals. For example, the thyroid gland maintains proper metabolic rates and levels of body fluids when it has ample iodine. Similarly, the pancreas, which controls blood sugar levels, needs chromium.
Eating foods rich in trace minerals helps support the body’s glandular functions. Unfortunately, many foods that are a mainstay of the modern diet are devoid of trace minerals. This is due in part to the depletion of minerals in the soil and the effects of processing. For example, raw sugar loses 94 percent of its chromium and 89 percent of its manganese during processing. Likewise, as wheat is processed into shite flour, it loses 50 percent of its chromium and 86 percent of its manganese.
Nutritional supplements rich in trace minerals, when taken with a well-balanced diet, help ensure the endocrine system gets the nutritional elements it needs to function properly.
The pituitary is roughly the size of a pea. The front lobe produces hormones that stimulate the thyroid, adrenals, testes and ovaries; encourage the growth of the body; and stimulate the secretion of milk in a mother’s breasts. Growth hormone affects almost every tissue in the body by regulating the amount of nutrients taken into cells. Too much growth hormone results in gigantism in children, while too little causes dwarfism.
The intermediate part of the pituitary may be involved with melanin secretion, which affects skin color.
The back lobe produces a hormone that causes the uterus to contract during childbirth and then stimulates the production of milk in the mammary glands. It also produces another hormone that regulates the retention of water by the kidneys.
Named for its pine-cone shape, the pineal gland may function in hormonal regulation, menstruation and sex development. It secretes a large number of active chemicals, the most important of which is melatonin, a substance that is present in higher concentrations during the night. Melatonin plays a role in controlling the sleep cycle. It also inhibits the secretion of gonadotropins. This is why tumors of the pineal gland may slow down the development of sexual maturity or in some cases accelerate it.
Thyroid and Parathyroid Glands
The thyroid controls the body’s metabolism and has the ability to concentrate iodine consumed with the diet. It also produces the hormone calcitonin, which helps to lower the level of calcium in the blood.
The parathyroid glands are small glands, usually four in number, embedded within the back of the thyroid. They produce the hormone parathormone, which regulates calcium and phosphorus metabolism. Calcium plays an important role in many metabolic processes. Too much calcium (hypercalcemia) or too little (tetany) can disrupt the normal function of the muscles and nerves. The body’s cells are extremely sensitive to changing amounts of blood calcium.
The thymus gland is central to the body’s defense mechanisms. It is composed largely of developing lymphocytes, a special type of infection-fighting cells. Although its function is not fully understood, it is known that the thymus plays an important role in developing immunities against various diseases. This is especially true during the early years of life. After puberty the thymus begins to shrink in size. Researchers have speculated that the progressive shrinking of the thymus gland a age increases is one of the reasons older people are somewhat prone to infections.
The hypothalamus is actually a tiny cluster of nerve cells located at the base of the brain. It serves as a link between the autonomic nervous system and the endocrine system. It is responsible for many body functions because it integrates and ensures appropriate responses to stimuli. In addition, it regulates hunger, thirst, sleep and wakefulness and also plays an important role in the regulation of most of the involuntary mechanisms of the body, including body temperature, sexual drive and the female menstrual cycle. Finally, it regulates the work of the pituitary gland.
The pancreas contains cells that secrete enzymes involved in the digestion of food, and other cells that produce the hormones insulin and glucagon. Insulin lowers the amount of sugar in the blood by facilitating its movement into the cells of the body. It is also important in the manufacture and storage of fats and proteins and in growth. Glucagon increases the amount of sugar present in the blood by causing the breakdown of fats and proteins. It tends to be secreted in times of stress.
The adrenal glands are essential for functions such as the body’s chemical regulation of sodium and potassium; blood concentration; pulse rate; smooth muscle relaxation or contraction; and dilation of pupils. Although it appears to be one organ, it is actually two small glands. The outer cortex of each is essential for the body’s chemical regulation. The adrenal cortex secretes two hormones, cortisol and aldosterone, which are known collectively as corticosteroids. They help the body reduce stress and are essential for life. Cortisol is an energy generator that regulates the conversion of carbohydrates into glucose and directs reserves to the liver. It also suppresses inflammation. Aldosterone regulates the mineral and water balance of the body. It prevents excessive loss of water through the kidneys and maintains the balance between sodium and potassium in the bloodstream. This balance is important to the contraction of muscles. The inner part, or medulla, secretes epinephrine and norepinephrine, two hormones that help the body reduce stress and are important in the fight-or-flight response.
The ovaries are located on each side of the abdomen. They have a dual function: producing and releasing ova (eggs), and secreting female sex hormones such as estrogen and progesterone. These hormones are responsible for the development of secondary sexual characteristics in girls after puberty and, along with others, are responsible for the regular bodily changes that accompany the menstrual cycle. Both of these functions cease at menopause.
Located in the scrotum, the testes produce sperm and secrete testosterone, which is responsible for the development of secondary sexual characteristics in boys after puberty, and for maintaining maleness throughout a man’s adult life.
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