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The Endocrine System
This will be a very detailed page about the endocrine system, so I will have to do it in stages. The reason I decided to embark on this very complex subject, is that often what affects one gland will invariably affect the others. The complex hormonal changes within a woman's body are often antagonistic and pregnancy, menopause etc are often the triggers to the beginning or worsening of hidden chronic illness. When one gland is over or underactive, the other glands feel the effects and suffer in their own way and of course, we feel the effects....big time. This is also referred to as a hormone imbalance and can also occur if the liver or kidneys are not working properly as their function is also important for clearing hormones from the blood.
The symptoms are often hard to diagnose and menopausal symptoms often sound like thyroid symptoms, oestrogen dominance, adrenal problems etc. It is also important to know that the endocrine, immune and nervous systems are also linked to eachother, therefore conditions affecting one system, will have a backlash on the others and this is displayed in our symptoms. Also endocrine disrupting chemicals have an effect on the immune and nervous systems. The endocrine system, also called the hormone system, consists of many glands-such as thyroid, pancreas, thymus, ovaries, adrenals, parathyroids, and also the controlling pituitary pineal and hypothalamus glands. They are a complex system and communicate by sending messages to each other via the release of hormones into the bloodstream. The hypothalamus sends a special hormone "encoded" message to the pituitary gland giving it instructions and the pituitary gland then "manages" all the other glands. The hypothalmus is a bit like the chief executive, with the pituitary the managing director over all the other glands. Once the message hits a receptor cell, it gives it instructions which are then carried out from creating energy from sugar to triggering labour or ovulation. Whilst not part of the endocrine system, other organs are also involved such as heart, lungs, kidneys and stomach. The messages sent are responsible for actioning and regulating many body functions such as metabolism, growth, body temperature, sleep, menstruation, ovulation, labour, menopause,and many other functions and are working all the time. Even now, scientists don't fully understand the endocrine system and it's complex hormone releasing purpose. However, what is known is that it is essential for life and a healthy body. Since the working of the endocrine system is extremely complicated, I will not try to discuss it too technically. We basically just need to know and discuss what each gland is responsible for, how it affects other glands and what can go wrong. Lets discuss each gland individually and as simply as possible We will begin at the top of the body, the brain as that is the headquarters and where it all starts.
Definition: A region of the brain that stimulates or suppresses the release of hormones in the pituitary gland. The power centre behind the master pituitary gland. The hormone messages from here are sent to the pituitary gland. The hypothalamus is also responsible for the messages controlling body temperature, sleep, fluid and electrolyte balance, levels of adrenalin, metabolism and blood pressure. It basically sends endocrine signals to the pituitary gland. It also links the endocrine and nervous systems. The Pituitary Gland Located at the base of the brain, attached to the hypothalamus and no larger than a pea, it is divided into three sections or lobes. Each lobe produces different hormones which then act in certain ways to send messages to other parts of the body. The anterior lobe is responsible for the production of growth hormone, prolactin (stimulates the production of breast milk shortly after delivery), ACTH (adrenocorticotropic hormone) which stimulates the adrenal glands, TSH (thyroid stimulating hormone) stimluates the thyroid gland, FSH follicle stimulating hormone which stimulates the ovaries (and testes in men), LH (luteinizing hormone) stimulates the ovaries (and testes in men). The Intermediate Lobe produces melanocyte-stimulating hormone which controls skin pigmentation. The posterior lobe produces ADH (antidiuretic hormone) which increases the absorption of water into the blood by the kidneys Oxytocin which causes the contracting of the womb in labour and also stimulates the production of breast milk. Some disorders of the pituitary gland include: Acromegaly: This is where the pituitary gland produces excess growth hormone. The disease affects the hands and feet first but other symptoms develope such as facial deformity, protruding jaw, body hair, joint pain and arthritis, fatigue and weakness especially in arms and legs, breast milk production in women, enlargement of organs such as heart, headaches, snoring, and many others. It has a gradual onset and may not become apparent for some years. Xrays taken over a period will observe changes in the patient. Blood tests to measure growth hormone. Most cases (90 per cent) of Acromegaly are due to benign tumours of the pituitary gland, but some are due to tumours of other organs such as lungs, pancreas or adrenal glands. The purpose of treatment is to restore the hormone production to normal and include removal of the tumour, radiation therapy, or an injection to block growth hormone production. Untreated acromegaly can lead to diabetes mellitus and hypertension as well as cardiovascular disease. It can also be fatal. Pituitary Tumours Many people have a pituitary tumour without even realising it and the majority of them are benign. Symptoms will depend on how large the tumour is and how much it is affecting hormone production. The most common of all pituitary tumours is called an endocrine inactive tumour. This type of tumour causes hypopituitarism (underactive pituitary gland) This may cause complete cessation of menstrual periods and sexual functioning in women. Hypopituitarism affects the anterior lobe of the pituitary gland and leads to inadequate amounts of other hormones such as luteinizing hormone and follicle-stimulating hormone. This results in absent mentrual cycles, infertility and vaginal dryness, insufficient production of growth hormone which results in dwafism or stunted growth in children, but usually no change to an adult. Being the anterior lobe that is affected, Hypopituitarism also causes: Underactive Thyroid due to insufficient TSH production, (has all the usual symptoms as on my thyroid page and insufficient corticotrophic production which leads to underactive adrenal glands. The symptoms of this are low blood sugar and blood pressure, fatigue and low stress tolerance. Insufficient prolactin production. This causes inability to produce breast milk in women, post delivery. The causes of Hypopituitarism can be direct or indirect (primary or secondary). Causes directly affecting the pituitary gland (primary): pituitary tumors inadequate blood supply to pituitary gland infections and/or inflammatory diseases sarcoidosis - a rare inflammation of the lymph nodes and other tissues throughout the body amyloidosis - a rare disease which causes the buildup of amyloid, a protein and starch, in tissues and organs radiation therapy surgical removal of pituitary tissue autoimmune diseases Indirectly affecting the pituitary gland (secondary causes affecting the hypothalamus) tumors of the hypothalamus inflammatory disease head injuries surgical damage to the pituitary and/or blood vessels or nerves leading to it. A doctor could suspect Hypopituitarism if a number of glands are underactive Diagnosis would be by blood tests to measure hormone levels in the blood, MRI or CT scans and treatment either by surgical removal of the tumour, radiation therapy, hormone replacement therapy or a combination.
Another type of pituitary tumour is called a prolactinoma, a benign tumor that produces the prolactin hormone. As many as 40 per cent of pituitary tumours can be prolactinomas. Pituitary tumours are diagnosed by blood tests to measure blood hormone levels, CT scans, MRI scans and treatment depends on a number of factors which may include surgery to remove of the tumour, radiation therapy, HRT, or a drug called bromocriptine (a hormone blocking drug). Pineal Gland
This gland is still being studied!! It is located deep in the brain above and behind the pituitary gland, produces melatonin through the synthesis of serotonin, a hormone responsible for the control of sleep patterns and is cone shaped and only the size of a grain of rice. Sometimes called the Third Eye, it was the last gland to be discovered and is shrouded in mystery. It reponds to light via messages through the retina, hence its ability to regulate sleep patterns and biological functions.
Melatonin is secreted in response to the length of nightime darkness. Melatonin is thought to be an important factor in ageing and Alzheimers Disease when output is disrupted in some way.. The gland performs a role in the identification of malignancies and disease through changes in pineal activity and these changes have been thought to be also linked to behavioural problems such as drug abuse and obsessive behaviour.
It is also thought that through an MRI examination of the gland, together with the measurement of serotonin and melatonin levels, impending disease may be identified. What should also be considered is that altering serotonin/melatonin levels artificially by using drugs such as barbiturates or amphetamines, alcohol, etc where the wake/sleep cycle is disrupted could in fact be detrimental to the health of the gland. This wake sleep cycle, disease, hormone synthesis and the pineal gland in general is being studied intensly. It seems there is more to the pineal gland than once thought.
The Thyroid Gland The majority of information you will find on my Thyroid Guide page
The control centre behind the thyroid is the pituitary gland which is a bit like a thermostat regarding thyroid function. When the pituitary senses that the levels have dropped below normal it will secrete TSH (thyroid stimulating hormone) which causes the thyroid to make more T3 and T4. Likewise when there is too much thyroid hormones, the pituitary acts by stopping production of TSH so that the levels return to normal. The purpose of blood tests are to measure whether you are making too much or too little thyroid hormone. Likewise, if you develope thyroid antibodies, this will indicate that you are devloping an autoimmune disease of the thyroid which will then go on to become either hyperthyroidism (Graves Disease) or hypothyroidism (Hashimotos Disease) Those who develope autoimmune thyroid disorders are more likely to develope other autoimmune diseases as well as other health problems. (see the Autoimmune Page If you suspect you have a thyroid disorder, it is important to be diagnosed quickly as untreated thyroid problems can also cause heart problems. The Parathyroid Glands Please also see my page Parathyroid Glands
These are actually unrelated to the thyroid itself except by location in the neck and the fact that they are part of the endocrine system. There are four parathyroid glands and their function is completely different as they are responsible for controlling levels of calcium in the body. Calcium is the only mineral in the body with glands that control it's levels.
The parathyroids are not discussed as much as the thyroid and many people are unaware of their existence. They are of exteme importance. When calcium levels are low the glands make a hormone called PTH taken from the bones to top up the levels in the body. When the levels are too high, it stop producing the hormone so that calcium levels drop. Like other endocrine glands, the parathyroids can also become diseased and become overactive (hyperparathyroidism) which is most common or underactive (hypoparathyroidism) which is rare. Hyperparathyroidism makes you feel very ill with too much calcium in the bloodstream and removal of the glands is the only option. Symptoms are much the same as thyroid disease.
Thymus Gland
70 per cent of those with the autoimmune disease Myasthenia Gravis have been found to have thymic hyperplasia or or benign tumours of the thymus. These tumours however, can become malignant. Hyperplasia results in the gland becoming enlarged. The gland has been found to be abnormal in those with myasthenia gravis. Hyperplasia can be caused by a number of reasons, including increased demand, chronic inflammatory response, hormonal dysfunctions, or compensation for damage or disease elsewhere in the body. The relationship between myasthenia gravis and the thymus gland is still not fully understood although it is thought that the thymus may give the incorrect messages to the developing immune cells which then results in an autoimmune disease due to the development of antibodies. The symptoms of myasthenia gravis generally affect swallowing, facial expression and eye movements due to an autoimmune attack on neuromuscular transmission. The severity varies from affecting facial muscles, a generalised weakness to severe and can include muscles used for breathing, as well as weakness in hands arms and legs. The disease is hard to diagnose, especially in it's early stages. A special blood test can detect the presence of immune molecules or acetylcholine receptor antibodies and these are normally raised in someone with myasthenia gravis. Other tests can be carried out by neuroligists recording weakened muscle responses and EMG, (electromyography) where single muscle fibres are stimulated by electrical impulses. The muscles will not respond well to this test in those with myasthenia gravis. A CT scan is also used to detect thymus abnormality or tumour. In HIV patients, immunity is destroyed therefore the thymus gland s inactive. Growth hormone injections are thought to stimulate the thymus thus restoring production of T-cells.
The Adrenal Glands
The Adrenal glands are triangular shaped and located at the top of both kidneys and are no bigger than a walnut. They are orange in colour and are about 3 inches long by and inch in height. There are two parts, an inner medulla and an outer cortex and each part secretes different hormones responsible for different actions. Once again the adrenal glands interact with the hypothalamus and pituitary gland and the hypothalamus produces corticotropin-releasing hormones, which stimulate the pituitary gland.
The pituitary gland, in response to the message, produces corticotropin hormones, which stimulate the adrenal glands to produce corticosteroid hormones. The hormones produced by the adrenal glands are essential for life.
The cortex secretes corticosteroids like hydrocortisone directly into the bloodstream. Hydrocortisone, also known as cortisol, controls the body's use of fats, proteins, and carbohydrates. The hormones secreted by the cortex have an effect on body functions such as metabolism, blood chemicals and characteristics of the body. Another hormone secreted by the cortex is corticosterone, which together with hydrocortisone hormones, suppresses inflammatory responses in the body and also affects the immune system. Aldosterone is another hormone secreted by the cortex which controls the level of sodium excreted into the urine, thus maintaining blood volume and pressure. Androgen hormones are also secreted in minor amounts by the adrenal cortex in the female body, but circulate more during menopause. An example of an androgenic hormone is testosterone which is responsible for male characteristics, hence why some women develope a deeper voice and facial hair during and after menopause. The Medulla secretes hormones to enable us to cope with stress. These hormones are adrenaline which increases heart rate and assists the flow of blood to the brain and muscles, reduces blood flow to the skin by producing sweat, assists in the conversion of glycogen to glucose in the liver which in turn raises blood sugar levels. It also causes the dilation of the pupils and widens the breathing tubes to facilitate the passage of oxygen into the lungs and noradrenaline which acts on receptors to stimulate the sympathetic nervous system, slows the heart rate and increases blood pressure. It can also be used medicinally by doctors to treat shock. What can go wrong? Like the other glands, problems can and do occur ranging from adrenal tumours to autoimmune disease such as Addisons disease and also Cushings syndrome and disease. Please see the adrenal page for more on this. Adrenal Tumours although rare can cause complete chaos within the body when present by causing the excess secretion of adrenal hormones. One type of adrenal tumour is called a pheochromocytoma which generally occurs in the 30 to 60 age group and is benign (can become malignant). However it causes the excess secretion of adrenaline and noradrenaline hormones. Since these hormones are involved in blood pressure and heart rate, the most common symptom is very high blood pressure, fast heart rate, palpitations, headaches, clammy skin as well as nausea and vomitting. The symptoms are often similar to other endocrine gland disorder symptoms such as overactive/underactive thyroid. Blood and urine tests are the diagnostic tools used and these measure hormone levels. CT scanning and radioisotope scan are also used and the latter is where a radioactive substance is injected to help the adrenal gland show up better and give a completely clear picture of the gland. The treatment will be surgical removal of the tumour although medication to control blood pressure would be used prior to surgery to bring it under control. Other adrenal problems are Addisons Disease (an underactive adrenal gland) which can be the result of many things such as infection or cancer, although most of the time the cause in not known. The symptoms of Addisons Disease also sound like other endocrine gland disorders such as weakness, fatigue, intolerance to the cold, muscular aches and pains giddiness and weight loss, although other symptoms could be present like black freckles, dehydration, nausea, vomitting, diarrhoea, skin discolouration aroung the vagina, nipples and mouth. It can be dangerous if not treated causing addisonian crisis and also, if the patient is also experiencing stress can bring on severe stomach pain, kidney failure, extreme weakness leading to shock hence the term addisonian crisis. Once again, please see my page on the adrenals and the Autoimmune page Addisons disease can be fatal but can also be treated which will involve taking hormone in the form of Corticosteroids for life as well as drugs to regulate potassium and sodium in the body. Then of course there is Adrenal Fatigue Please see my Adrenal page for more information. This is a condition that can affect you if you suffer from prolonged periods of stress. Thyroid patients can also suffer from this, as can some other autoimmune disease sufferers. Cortisol acts as an anti-inflammatory over autoimmune reactions, but the levels of this hormone are insufficient to cope with the autoimmune reactions taking place in those suffering with an autoimmune disease, since the glands or tissues involved in the attack by our systems are to such a degree that the adrenals glands can not cope. For example, in Hashimoto's disease, the thyroid is constantly under attack by antibodies until it is rendered useless. It stands to reason that once cortisol is in constant demand and the adrenals can not cope, then the pituitary gland can't cope either and neither can the hypothalamus. It is this knock on effect that damages the body. Also many tooth problems are a result of adrenal fatigue from tooth abcesses to gum infection to mercury filling. Mercury amalgams suppress cortisol production and sometimes adrenal fatigue can be as a direct result of poor dental work or mercury amalgams. Make sure your dentist does not use mercury in your mouth. Since stress and adrenal fatigue affect the immune system, many people with adrenal fatigue also suffer from the Herpes 1 or 2 virus. Herpes breakouts then put pressure on the immune system and the adrenals leading to further adrenal fatigue. Please see this information page for more about adrenal fatigue and solutions.
Largely dismissed by the medical profession who won't always carry out tests to establish whether we have AF or AI (adrenal insufficiency) as it is also known, a bit like chronic fatigue syndrome, doctors assume it is all in our minds. Ironically, CFS can also cause adrenal fatigue and vica versa. Since the adrenals assist in our body's ability to cope with stress, whether this stress is financial, relationships, falling in love, children, drug abuse and addictions such as alcohol and cigarettes, labour, illness, work committments, bereavement, abuse, to merely a small argument or even environmental triggers, no matter how mild or severe the stress, being individual to each person and their ability to cope, the adrenals and their hormones play a centre stage role. Of course, the more prolongued or persistant the stress or whether it is a regular occurance, or even a bout of intense stress such as a bereavement, the adrenals can become burnt out from constant demand. We then suffer adrenal fatigue. unfortunately it becomes a vicious circle as suffering from adrenal fatigue then becomes an additional source of stress. Also if you suffer from a chronic illness, the adrenals are put under additional stress, sometimes critical. This causes their hormone output to be diminished. Although they still work, they don't work well enough to maintain health. The occurance of adrenal fatigue can vary from a temporary bout to a lifetime if the symptoms are not picked up and treated. Your very wellbeing depends on the health of your adrenal glands. The symptoms of adrenal fatigue sound familiar to thyroid disease in some ways with the persistant tiredness, feeling emotionally overwhelmed and unable to cope with situations and this can build up until we can't cope with anything at all. Inability to get up in the mornings no matter how much sleep we have had, low immune response and inability to recover from viruses and minor illnesses to persistent mouth ulcers and infections. Cravings for sweet things and/or salty snacks. Can we recover? With treatment, yes. See here for more on this. Please read Adrenal Fatigue for more information and a recovery programme. The Pancreas
Shaped a bit like a fish, it is divided into parts with the wide end called the "head", the thin end the "tail" and the middle portion the "body" It produces digestive enzymes which flow into the main pancreatic duct, and also the hormones insulin and glucagon and other digestive hormones like somatostatin and gastrin. The part of the pancreas that produces digestive enzymes is called the exocrine pancreas and makes up most of the pancreas, and the part dealing with hormones such as insulin and glucagon production is of course the endocrine pancreas. As we know, the digestive system breaks down our food and after about two hours it moves into the duodenum, partially digested.
Upon its arrival at the duodenum, the pancreas releases the enzymes to further digest the food until it is a lot smaller and then it gets absorbed into the body by the small intestine.
The endocrine pancreas is responsible for insulin and glucagon production which regulates blood sugar levels and keeps them stable. This page is mainly devoted to the endocrine pancreas. If the pancreas does not make enough insulin, then diabetes results. please see my autoimmune page for more information about diabetes.There are two types of diabetes type 1 and type 2. Type 1 is an autoimmune disease (Diabetes Mellitus) caused by an autoimmune attack to the beta cells of the pancreas which causes a build up of sugar in the bloodstream. Since insulin is not produced it can not act to reduce this build up and insulin injections are necessary. Blood sugar levels are regulated by the production of insulin, too high and the pancreas produces more insulin, too low and the pancreas releases less. since the pancreatic hormones are responsible for regulations of salts and sugars in the body, once these are out of balance, we become ill. The endocrine pancreas accounts for only around 5 per cent of the mass of the pancreas gland. The endocrine pancreas secretes hormones directly into the bloodstream and not into ducts like the exocrine pancreas. Pancreatic hormones Insulin The purpose of insulin is to regulate blood sugar by causing cells to use glucose. Like other endocrine glands insulin is secreted or inhibited in reponse to blood sugar levels in the body. When insulin is deficient, Diabetes results, similarly when insulin is too high, hypoglycemia results. Glucagon Glucagon assists insulin in blood sugar regulation and is secreted when blood sugar is low and inhibited when blood sugar is high. It is basically the opposite to insulin. Excess Glucagon production causes hyperglycemia. Somatostatin Regulates and controls the production of other endocrine hormones and is also produced in the hypothalamus. It is secreted in response to high levels of other endocrine hormones and its production stops when levels are low.
Anyone who has their pancreas removed would of course need to take not only insulin but also pancreatic enzymes for digestion.
Please click here to go to the thyroid guide
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Hypothalamus
However, for the purpose of this page, the thyroid gland is located in the neck in close proximity to the windpipe and is a red/brown colour. It consists of two lateral lobes joined by the "isthmus" which is a small piece of tissue and is a butterfly shape. It produces two hormones which control metabolism, T3 (triiodothyronine) and T4 (thyroxine). T4 is also converted into T3 in the cells and tissues of our body. If too much is secreted then the body works on "fast" with symptoms such as diarhoea, fast heart rate etc (hyperthyroidism). Likewise if too little is secreted, the body works slowly and you will have a slow heart rate and contipation (hypothyroidism).
The thymus gland lies beneath the top of the breastbone, partially in the chest and partially in the neck. It is a pinkish-grey colour and divided into two lobes. It is responsible for processing T-lymphocytes which govern immunity in our cells, helping our cells to recognise invading bacteria, abnormal cell growth and viruses and thus, destroy them. Without a thymus gland we would have no resistence to disease. When we have acute infection, the thymus gland can shrivel very quickly to half it's size. It is because of this that scientists once thought it had no purpose in adulthood. However, this has now been proved incorrect. It plays an important part in the development of immunity in our early lives. The gland starts off quite large in an infant, but gradually begins to shrink as we age until it is barely detectable in the elderly.
The pancreas is part of the digestive system as well as the endocrine system. It is about 6 inches long and its position in the abdomen is roughly where your ribs join at the bottom of the sternum and it is behind the stomach. It is in close proximity to your liver. It is greyish pink in colour and spongy.
