Your one minute guide to the endocrine system
The endrocrine system’s primary aim is to maintain a stable and balanced internal environment, known as homeostasis. It does this by regulating bodily functions such as metabolism, growth and sexual development. It works through a series of glands that release hormones into the bloodstream. These hormones travel to the organs and tissues of the body where they bind to the receptor cells, which are protein molecules embedded in the membrane or cytoplasm of the cell. The cells are encouraged to develop and act in certain ways according to the signals that the hormone transmits to them.
It is these hormones which determine the development of sexual characteristics in puberty. They also determine how energy is stored and used in the body, as well as how the body controls fluid, salt and sugar levels in the blood. It takes only a very small level of hormones to trigger significant reactions in the body. When the chemical or nutrient level is too high or low, the endocrine glands secrete more hormones until the balance has been restored. Depending on what kind of information it receives, the endocrine glands can start and stop the secretion of hormones in to the blood stream.
There are eight major glands that help in the functioning of the endocrine system. These are the pituitary gland, hypothalmus, thyroid, parathyroid, adrenals, pineal body and the reproductive glands (testes and ovaries).
The pituitary gland is integral to the whole system. Situated in the base of the brain, it produces and secretes hormones according to the internal and external changes that affect the body. The hypothalamus, which is another brain based gland, notifies the pituitary gland of these changes.
The pituitary gland consists of two parts, the anterior and the posterior lobes. The anterior lobe regulates the activity of the thyroid, adrenals and the reproductive glands. The posterior lobe produces oxytocin, which is responsible for uterine contractions and lactation, and vasopressin which promotes water reabsorption and increasing blood volume.
The thyroid gland enables the body to generate energy and regulate its temperature. It produces two hormones called triiodothyronine and thyronine, also known as T3 and T4.
Attached to the thyroid are four smaller glands known as the parathyroids. They regulate the level of calcium in the blood by releasing the parathyroid hormone, which combines with calcitinin, a hormone produced by the thyroid.
The adrenal glands are located on top of the kidneys. They produce four hormones in total, which include glucocortoids, mineralocortoids, androgen and catecholamines. Glucocorticoids help to protect against stress, while mineralocorticoids work to maintain the right level of sodium in your body. Androgen helps to maintain muscle and body density, as well as general wellbeing. Catecholamines are stop the body from crashing in “flight or fight” situations.
The reproductive glands help to develop sexual characteristics at puberty, and they also facilitate reproductive functions such as the menstrual cycle. For men, their reproductive glands are situated in the testes, and they produce a hormone called testosterone. For women, their reproductive glands are based in the ovaries, and they produce oestrogen and progesterone.
The pineal body is located in the centre of the brain, and it secretes Melatonin which controls the body’s sleeping cycles.
The pancreas is also involved in the endocrine system, eventhough it isn’t a gland. It produces two important hormones known as insulin and glucagon, which control the level of glucose in the blood. When the pancreas fails to secrete these hormones it can lead to diabetes.
Five Quick Facts
- There are 30 different hormones in the body, each with their own function.
- The endocrine system has no ducts at all. It relies on the bloodstream to transfer all of the hormones it produces to different parts of the body.
- The exocrine glands are different from the endocrine glands, because they excrete hormones by way of a duct to the external environment. Examples of exocrine glands include sweat glands, salivary glands and mammary glands.
- Failures in the endocrine system can lead to variety of diseases related to reproduction, development and hormone maintenance. For example, if it produces too much growth hormone this can lead to diseases such as gigantism. Too little growth hormone can lead to growth hormone deficiency – where children grow more slowly than others. Diabetes, osteoporosis and polycystic ovary syndrome are some other examples of endocrine-related conditions.
- The endocrine and the nervous system work together to regulate bodily functions. The nervous system stimulates the hypothalmus, which in turn triggers the pituitary gland to release hormones.
Hint to learning the system
It’s easier to remember how the system works if you think of it like a computer, in the sense that it sends information in the same way. The hypothalmus is like the mouse, it responds to external stimuli to initiate change. The pituitary is like the hard drive, it processes the stimuli and sends out hormones (information) to different areas of the body to effect the desired changes.
If you are struggling to remember all of the different glands involved in the endocrine system, think of a mnemonic device to make it easier. Why not try – HPPTPAPO – hypothalmus, pineal, pituitary, thyroid, parathyroid, adrenal, pancreas and ovary.
- Endocrine: (en-doh-krin)
- Pituitary: (pit-too-uh-ter-ee)
- Hypothalmus: (hahy-puh-thal-uh-muhs)
- Thyroid: (thy-royd)
- Parathyroid: (par-uh-thahy-royd)
- Ovary: (oh-vuh-ree)
- Testes: (tes-teez)
- Pineal: (pin-ee-uh-l)
- Adrenal: (uh-dree-nul)
- Adrenaline: (uh-dren-nuh-lin)
- Pancreas: (pan-kree-us)
- Diabetes: (dye-uh-bee-teehs)
- Glucose: (gloo-kose)
- Endocrinologist: (en-doh-krin-all-oh-jist)
- Anterior: (an-teer-ee-er)
- Posterior: (po-steer-ee-er)
- Oxytocin: (ok-si-toh-suhn)
- Vasopressin: (vas-oh-pres-in)
- Triiodothyronine: (trahy-ahy-oh-doh-thahy-ruh-neen)
- Thyronine: (thy-roh-nine)
- Glucocorticoid: (gloo-koh-kawr-ti-koid)
- Mineralocorticoid: (min-er-uh-loh-kawr-ti-koid)
- Androgen: (an-druh-juhn)
- Catecholamine: (kat-i-kol-uh-meen)
- Melatonin: (mel-uh-toh-nin)
- Insulin: (in-suh-lin)
- Glucagon: (gloo-kuh-gon)
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