What is the Endocrine System?

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Endocrine System
Although the endocrine glands are the body's main hormone producers, some other organs not in the endocrine system — such as the brain, heart, lungs, kidneys, liver, and skin — also produce and release hormones. Stimulates the lining of the uterus for fertilization; prepares the breasts for milk production. Controls key functions in the body; acts as an anti-inflammatory; maintains blood sugar levels, blood pressure, and muscle strength; regulates salt and water balance. The term hormone is sometimes extended to include chemicals produced by cells that affect the same cell autocrine or intracrine signalling or nearby cells paracrine signalling. Cushing's disease and Addison's disease are pathologies involving the dysfunction of the adrenal gland. The foundations of the endocrine system are the hormones and glands.

Endocrine Disruption

What Is the Endocrine System?

The hormone-receptor complex switches on or switches off specific biological processes in cells, tissues, and organs. The female ovaries, male testes, and pituitary, thyroid, and adrenal glands are major constituents of the endocrine system. Hypothalamus - The hypothalamus links our endocrine and nervous systems together.

The hypothalamus drives the endocrine system. This gland has two lobes, the posterior and anterior lobes. The posterior lobe secretes hormones that are made by the hypothalamus. The anterior lobe produces its own hormones, several of which act on other endocrine glands. These glands produce hormones in response to stress and regulate blood pressure, glucose metabolism, and the body's salt and water balance.

Both hormones help regulate the concentration of glucose sugar in the blood. The major categories of gonadal steroids are androgens, estrogens, and progestins, all of which are found in both males and females but at different levels. It is important to gain a better understanding of what concentrations of chemicals found in the environment may cause an adverse effect. Various types of scientific studies epidemiology, mammalian toxicology, and ecological toxicology are necessary to resolve many of the scientific questions and uncertainty surrounding the endocrine disruptor issue.

Many such studies are currently underway by government agencies, industry, and academia. Contact Us to ask a question, provide feedback, or report a problem. Jump to main content. An official website of the United States government. What is the Endocrine System? They are made up of: Glands located throughout the body; Hormones that are made by the glands and released into the bloodstream or the fluid surrounding cells; and Receptors in various organs and tissues that recognize and respond to the hormones.

Learn more about endocrine systems: Why are hormones important? Some types of glands release their secretions in specific areas. For instance, exocrine pronounced: EK-suh-krin glands , such as the sweat and salivary glands, release secretions in the skin or inside the mouth. Endocrine glands , on the other hand, release more than 20 major hormones directly into the bloodstream where they can be transported to cells in other parts of the body.

Nerve cells in the hypothalamus control the pituitary gland by producing chemicals that either stimulate or suppress hormone secretions from the pituitary. Although it is no bigger than a pea, the pituitary pronounced: It's often called the "master gland" because it makes hormones that control several other endocrine glands.

The production and secretion of pituitary hormones can be influenced by factors such as emotions and changes in the seasons. To accomplish this, the hypothalamus provides information sensed by the brain such as environmental temperature, light exposure patterns, and feelings to the pituitary. The tiny pituitary is divided into two parts: The anterior lobe regulates the activity of the thyroid, adrenals, and reproductive glands. The anterior lobe produces hormones such as:.

The pituitary also secretes endorphins pronounced: In addition, the pituitary secretes hormones that signal the reproductive organs to make sex hormones. The pituitary gland also controls ovulation and the menstrual cycle in women. The posterior lobe of the pituitary releases antidiuretic pronounced: THY-royd , located in the front part of the lower neck, is shaped like a bow tie or butterfly and produces the thyroid hormones thyroxine pronounced: These hormones control the rate at which cells burn fuels from food to produce energy.

The production and release of thyroid hormones is controlled by thyrotropin pronounced: The more thyroid hormone there is in a person's bloodstream, the faster chemical reactions occur in the body. Why are thyroid hormones so important? There are several reasons — for example, they help kids' and teens' bones grow and develop, and they also play a role in the development of the brain and nervous system in kids.

Attached to the thyroid are four tiny glands that function together called the parathyroids pronounced: They release parathyroid hormone , which regulates the level of calcium in the blood with the help of calcitonin pronounced: The body also has two triangular adrenal pronounced: The adrenal glands have two parts, each of which produces a set of hormones and has a different function:.

It secretes melatonin pronounced: The gonads are the main source of sex hormones. Most people don't realize it, but both guys and girls have gonads. In guys the male gonads, or testes pronounced: TES-teez , are located in the scrotum. They secrete hormones called androgens pronounced: AN-druh-junz , the most important of which is testosterone pronounced: These hormones tell a guy's body when it's time to make the changes associated with puberty , like penis and height growth, deepening voice, and growth in facial and pubic hair.

Working with hormones from the pituitary gland, testosterone also tells a guy's body when it's time to produce sperm in the testes. A girl's gonads, the ovaries pronounced: OH-vuh-reez , are located in her pelvis.

They produce eggs and secrete the female hormones estrogen pronounced: ESS-truh-jen and progesterone pronounced: Estrogen is involved when a girl begins to go through puberty. During puberty, a girl will experience breast growth, will begin to accumulate body fat around the hips and thighs, and will have a growth spurt. Estrogen and progesterone are also involved in the regulation of a girl's menstrual cycle.

These hormones also play a role in pregnancy. Although the endocrine glands are the body's main hormone producers, some other organs not in the endocrine system — such as the brain, heart, lungs, kidneys, liver, and skin — also produce and release hormones.

PAN-kree-us is also part of the body's hormone-secreting system, even though it is also associated with the digestive system because it produces and secretes digestive enzymes. The pancreas produces in addition to others two important hormones, insulin pronounced: IN-suh-lin and glucagon pronounced: They work together to maintain a steady level of glucose, or sugar, in the blood and to keep the body supplied with fuel to produce and maintain stores of energy.

Once a hormone is secreted, it travels from the endocrine gland that produced it through the bloodstream to the cells designed to receive its message. These cells are called target cells. Along the way to the target cells, special proteins bind to some of the hormones.

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