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    adrenal gland

    adrenal gland: tuyến thượng thận

    (cũng gọi là suprarenal gland)

    adrenal gland is a small gland that makes steroid hormones, adrenaline, and noradrenaline. These hormones help control heart rate, blood pressure, and other important body functions. There are two suprarenal glands, one on top of each kidney

    tuyến thượng thận là một tuyến nhỏ sản sinh hóc môn xtê-rô-ít, hóc-môn a-đrê-na-lin và hoóc - môn làm tăng huyết áp, nhịp tim và đường huyết. những loại hóc môn này giúp kiểm soát nhịp tim, huyết áp và các chức năng quan trọng khác của cơ thể. Có hai tuyến thượng thận, ở trên đầu mỗi thận

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    Functional Anatomy of the Adrenal Gland

    Functional Anatomy of the Adrenal Gland

    The two adrenal glands are located immediately anterior to the kidneys, encased in a connective tissue capsule and usually partially buried in an island of fat. Like the kidneys, the adrenal glands lie beneath the peritoneum (i.e. they are retroperitoneal). The exact location relative to the kidney and the shape of the adrenal gland vary among species.

    Inspection of a mammalian adrenal gland that has been sectioned reveals two distinct regions, as demonstrated to the right with a sheep adrenal (click the image to flip between surface and cut views):
    • An inner medulla, which is a source of the catecholamines epinephrine and norepinephrine. The chromaffin cell is the principle cell type. The medulla is richly innervated by preganglionic sympathetic fibers and is, in essence, an extension of the sympathetic nervous system.
    • An outer cortex, which secretes several classes of steroid hormones (glucocorticoids and mineralocorticoids, plus a few others). Histologic examination of the cortex reveals three concentric zones of cells that differ in the major steroid hormones they secrete.

    Despite their organization into a single gland, the medulla and cortex are functionally different endocrine organs, and have different embryological origins. The medulla derives from ectoderm (neural crest), while the cortex develops from mesoderm. The utility, if any, of having them together in one discrete organ is not obvious. In some species, amphibians and certain fish, for example, two separate organs are found.

    http://www.vivo.colostate.edu/hbooks...l/anatomy.html

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    Overview of Adrenal Histology

    Overview of Adrenal Histology

    The adrenal gland is encased in a connective tissue capsule that extends septae into the substance of the gland. The organ is richly vascularized and capsular blood vessels, nerves and lymphatics penetrate along with the connective tissue septae.

    The most distinctive feature of the adrenal is its partitioning into cortex and medulla. The medulla is fairly homogeneous, but even when viewed a low power, three concentric zones can be distinguished in the cortex:
    • zona glomerulosa - thin, outermost zone
    • zona fasiculata - thick, middle zone
    • zona reticularis - thin, inner zone
    The three cortical zones and part of the medulla are evident in the section of rabbit adrenal gland seen below.



    A higher magnification montage of a feline adrenal gland is available.

    Based on embryologic origin and type of hormones produced, the cortex and medulla are best though of as separate endocrine organs. The medulla produces catecholamines and the cortex produces several steroid hormones, as depicted in the table below. There is some overlap in hormones synthesized by the zonae fasiculata and reticularis (i.e. cells in the fasiculata produce a small amount of androgens and cells in the reticularis secrete some cortisol).

    mineralocorticoids (aldosterone)
    glucocorticoids (cortisol)
    sex steroids (androgens)
    catecholamines (epinephrine and norepinephrine)


    Histologic examination of the adrenal reveals a rich vasculature. Numerous small arteries from several sources ramify over the surface of the gland and penetrate into the gland into two ways:
    • Cortical arteries and arterioles branch into capillary beds within the cortex to supply that area, then coalesce into veins at the corticomedullary junction.
    • Medullary arteries and arterioles penetrate the cortex without branching, then form capillary beds in the medulla.
    Blood from both cortical and medullary veins empties through a single large central vein, which leaves the adrenal and anastomoses with either the vena cava or renal vein.


    http://www.vivo.colostate.edu/hbooks..._overview.html
    Lần sửa cuối bởi thanhthanh, ngày 23-02-2013 lúc 11:28 AM.

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    What is the adrenal gland?

    WHAT IS THE ADRENAL GLAND?

    The adrenal glands are approximately two and half by one inch long yellowish-orange colored glands that are found just above the kidneys. Adrenal glands provide a very important function in protecting the body against stress. This function is carried out by secretion of a number of different types of hormones by the adrenal gland.

    Adrenal cortex

    The adrenal gland is actually two glands that are fused together into one gland. The outer part of the adrenal gland also called the adrenal cortex produces steroid hormones that are involved in regulating a number of different body functions.

    The adrenal cortex also produces a hormone called aldosterone that is involved in regulating the amount of salt and water in your body.


    Adrenal medulla

    The inner part of the adrenal gland is called the adrenal medulla. The adrenal medulla produces hormones called catecholamines such as adrenaline and noradrenaline.Catecholamines play a role in the response to acute or sudden severe stress, for example during life threatening event.

    Catecholamines are responsible for the palpitations (racing heart), sweatiness, widening of eyes and shakiness of the hand when faced with sudden fear or other stressful situation.


    http://www.surgery.usc.edu/divisions...asdiseases/web pages/Endocrine tumors/adrenal/what is the adrenal.html

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    Tumours of the adrenal glands

    Tumours of the adrenal glands

    Tumours of the adrenal glands are very rare. The adrenal glands are part of the endocrine system, so the tumours are also calledendocrine tumours.

    On this page

    We hope this information answers your questions. If you have any further questions, you can ask your doctor or nurse at the hospital where you are having your treatment.

    The endocrine system

    The endocrine system is a network of endocrine glands and nerves throughout the body. Endocrine glands produce and release hormones, which circulate around the body in the blood. Hormones keep an even balance of chemicals and fluid within the body, and help us respond to changes in the environment. Normally, the hormones released by endocrine glands are carefully balanced to meet the body's needs.

    The endocrine glands include the pituitary gland (which lies immediately underneath the brain), the thyroid gland (in the front of the neck), the parathyroid glands (just behind the thyroid gland), and the adrenal glands (on top of the kidneys in the abdomen).

    Endocrine tumours

    Endocrine tumours are a rare group of tumours that start in the cells of the endocrine system. Most endocrine tumours are non-cancerous (benign), but some are cancerous (malignant).

    Endocrine tumours are classified according to:
    • the particular endocrine glands that are involved
    • the type of cell from which the cancer developed
    • the part of the body that is affected.

    Position of the adrenal glands


    The adrenal glands

    The adrenal glands are part of the endocrine system. There are two adrenal gland - one sits on the top of each kidney. The adrenal glands produce a number of vital hormones essential for survival.
    There are two parts of the adrenal glands. The outer part is called the cortex and the inner part is called the medulla.

    When a tumour develops in the adrenal glands, it often causes too much of a particular hormone to be produced. The type of hormone that is overproduced depends on the part of the adrenal gland affected by the tumour.

    Some endocrine tumours may not cause an overproduction of hormones and don't cause any obvious symptoms. These are known as non-functioning tumours.

    The adrenal cortex

    The adrenal cortex produces different types of hormones, which are known collectively as steroids. They regulate different mechanisms within the body.

    The different types of steroids are:

    Glucocorticoids

    These regulate the way the body uses carbohydrate, protein and fat. They also affect the levels of glucose (sugar) in the blood.

    Mineralocorticoids

    These control the balance of sodium (salt) and water in the body, which maintains the amount of blood in the heart and circulatory system, and regulates blood pressure.

    Sex hormones

    Although male hormones (androgens) and female hormones (oestrogen and progesterone) are mainly produced by the testicles and ovaries, the adrenal cortex also produces small amounts of androgens and oestrogen in both men and women.

    The adrenal medulla

    The adrenal medulla produces the hormones adrenaline (epinephrine) and noradrenaline (norepinephrine). These hormones make the heart beat faster, cause sweating, increase blood supply to vital organs, slow down digestion and make the eyes’ pupils dilatate. These effects are important in helping the body to react to emergency situations. Adrenaline and noradrenaline are sometimes called the hormones of 'fight or flight'.

    Types of adrenal tumours

    Tumours of the adrenal gland can develop in either the cortex or the medulla.

    Benign tumours of the cortex are called adrenal cortical adenomas. Malignant tumours are called adrenal cortical carcinomas.

    The most common type of tumour in the medulla is called a phaeochromocytoma. These can be benign or malignant. A small number of phaeochromocytomas start outside the medulla part of the adrenal gland and are known as extra-adrenal phaeochromocytomas.

    Only one adrenal gland is usually affected. Rarely, tumours may occur in both adrenal glands. These are known as bilateral adrenal tumours.

    Causes of adrenal tumours

    As with many other types of cancer, the exact causes of adrenal cancer are usually unknown. However, the risk of developing an adrenal tumour is increased in people who have Multiple endocrine neoplasia (MEN1 and MEN2).

    MEN1 and MEN2 are very rare conditions caused by an inherited faulty gene. MEN1 is associated with adrenal adenomas (benign) and MEN2 is associated with phaeochromocytomas (which can sometimes be malignant). People who have relatives with MEN1 or MEN2 can ask their GP to refer them to a family cancer clinic for advice and genetic testing.

    Signs and symptoms of adrenal tumours

    Functioning tumours may cause symptoms because they produce excess amounts of particular hormones. The symptoms will depend on the hormone that is being overproduced.

    When a tumour doesn't produce high levels of hormones (is non-functioning), it can start to cause symptoms after a period of time because of its position or size. Pressure on surrounding organs may cause symptoms such as pain.

    Adrenal cortical carcinomaBack to top

    About two out of three adrenal cortical carcinomas cause symptoms by producing high levels of one or other of the adrenal cortex hormones. The particular hormone being overproduced will determine the symptoms.

    Glucocorticoid

    An overproduction of this hormone can lead to weight gain, particularly in the trunk area, and usually some muscle wasting in the limbs, making them appear thinner. There can also be an accumulation of fat at the back of the neck, which can lead to a visible lump. There can be a swelling of the cheeks and face, giving your face a rounded appearance.

    Some people have diabetes, which can make them more thirsty and cause them to pass urine more frequently. Other symptoms include high blood pressure (hypertension), weakened bones (osteoporosis), depression, and increased hair growth on the face, arms and upper back.

    The term Cushing's syndrome is used to describe this whole group of symptoms.

    Mineralocorticoids

    An increase in mineralocorticoids can lead to a rise in blood pressure, muscle cramps, feeling thirsty, and passing more urine than usual. However, there are many other causes of raised blood pressure that are much more common than adrenal cortical cancers.

    Sex hormones

    In women, increased production of androgens can lead to the development of male features such as a deepening of the voice and baldness. You may notice a change in your periods. In men, excess production of oestrogen may cause a loss of libido, impotence, and sometimes some swelling and enlargement of the breasts.

    Phaeochromocytoma

    Phaeochromocytoma is the most common type of adrenal medulla tumour. Symptoms include:
    • sudden attacks of panic and anxiety
    • headaches
    • pallor or flushing
    • sweating
    • palpitations (awareness of a rapid heartbeat)
    • high blood pressure (hypertension)
    • irritability and mood changes
    • weight loss.
    Most phaeochromocytomas are benign, but they can be malignant (cancerous). If you notice any of the above symptoms, contact your GP. But remember that these can also be caused by other conditions.

    Diagnosis of adrenal tumours
    Back to top


    Tumours of the adrenal gland can be very difficult to diagnose. Usually you begin by seeing your GP, who will examine you and refer you to a hospital specialist for expert advice and treatment.


    The hospital specialist will ask you about your general health and any previous medical problems before examining you. You may have a blood test and a chest x-ray to check your general health. Several other tests may also be used.

    Blood and urine tests

    Samples of blood and urine are checked for the presence of certain hormones. A sample of urine may be collected over a 24-hour period. Sometimes it's necessary to fast (not eat) overnight before having certain blood tests. These tests may be repeated to monitor any consistent changes in hormone levels.
    X-rays and scans

    A combination of x-rays and scans will be taken to find there the tumour is and whether it has spread.

    Abdominal ultrasound

    This test uses sound waves to build up a picture of the abdomen and surrounding organs. It is done in the hospital scanning department. You will be asked not to eat, and to drink clear fluids only (nothing fizzy or milky) for 4-6 hours before the scan.

    Once you’re lying comfortably on your back, a gel is spread on to your abdomen. A small device like a microphone, which produces sound waves, is then moved over the area. The sound waves are converted into a picture using a computer. The test is completely painless and takes about 15-20 minutes.

    CT (computerised tomography) scan

    A CT scan takes a series of x-rays that build up a three-dimensional picture of the inside of the body. The scan is painless and takes 10-30 minutes. It may be used to find out where the cancer started (the primary tumour) or to check for any spread of the disease (metastases). CT scans use a small amount of radiation, which will be very unlikely to harm you and will not harm anyone you come into contact with. You will be asked not to eat or drink for at least four hours before the scan.

    You may be given a drink or injection of a dye, which allows particular areas to be seen more clearly. For a few minutes, this may make you feel hot all over. If you are allergic to iodine or have asthma you could have a more serious reaction to the injection, so it’s important to let your doctor know this beforehand.

    MRI (magnetic resonance imaging) scan

    This test is similar to a CT scan but uses magnetism instead of x-rays to build up a detailed picture of areas of your body. Before the scan you may be asked to complete and sign a checklist. This is to make sure that it’s safe for you to have an MRI scan.

    Before having the scan, you’ll be asked to remove any metal belongings, including jewellery. Some people are given an injection of dye into a vein in the arm. This is called a contrast medium and can help the images from the scan to show up more clearly. During the test you’ll be asked to lie very still on a couch inside a long cylinder (tube) for about 30 minutes. It's painless but can be slightly uncomfortable, and some people feel a bit claustrophobic during the scan. It’s also noisy, but you’ll be given earplugs or headphones. You'll be able to hear, and speak to, the person operating the scanner.

    I-123-MIBG scan

    A chemical called I-123-MIBG (meta-iodobenzylguanidine) may be used to show up the site of a phaeochromocytoma on a scan. I-123-MIBG contains mildly radioactive iodine and is taken up by adrenal cells. The scan takes place over two consecutive days in the nuclear medicine department. On the first day, you will go to the department twice. In the morning you will be given an injection in the arm. You can then stay in, or leave, the hospital. You will go back to the department in the afternoon to have a scan with a gamma camera, which lasts for about an hour. The next morning you will have more pictures taken for about one and a quarter hours. At this point you may be given another injection.

    Biopsy

    A small sample of cells is taken from the tumour to be examined under a microscope. The biopsy may be carried out under a local or general anaesthetic.

    Angiogram

    An angiogram is a technique used to assess the flow of blood through the blood vessels of the adrenal glands. An injection is given into a vein in the arm and a scan of the adrenal glands is then taken.

    Treatment for adrenal tumours

    Treatment depends on a number of factors, such as the type and size of the tumour, and whether or not it has spread. It therefore varies from person to person.

    Surgery

    If the tumour is contained in one area, or if there has been only limited spread, surgeryis usually the first choice of treatment. If it is possible to remove the tumour completely, you might not need any other treatment.

    The type of operation you will have depends on the size and exact position of the cancer. Sometimes the affected adrenal gland and kidney need to be removed.

    If the tumour has spread to other parts of the body, surgery may still be possible to remove the part of the tumour that is producing too many hormones. This is often referred to as tumour debulking.

    If the tumour is causing a blockage, for example, in the bowel, surgery may be helpful to relieve the blockage.

    Non-surgical treatments

    Drugs to lower blood pressure

    These are known as anti-hypertensive medicines.

    Chemotherapy

    This is the use of anti-cancer (cytotoxic) drugs to destroy cancer cells. Chemotherapymay sometimes be used to treat adrenal tumours that have spread. The aim of the chemotherapy is to shrink the tumour and reduce the amount of hormones it is producing.

    Radiotherapy

    This is the use of high-energy rays to destroy cancer cells. Sometimes it is given following an operation to destroy any remaining cancer cells. Radiotherapy may also be given to treat symptoms such as pain.

    Radionuclide therapy

    Some types of tumour may take up large amounts of particular chemicals such as MIBG (meta-iodobenzylguanidine). To treat these tumours, the chemical can be attached to a dose of a radioactive substance. As the cancer takes up the chemical, it also takes in the radioactivity.

    To test whether or not the tumour takes up large quantities of these chemicals, you will have a scan using a tiny amount of radioactivity. If the tumour takes up the radioactivity, the treatment will be given using a higher dose of the radioactive substance. You may need to be looked after in a room by yourself for a few days, so that other people are not exposed to the radioactivity.

    Clinical trials

    Research into treatments for adrenal tumours is ongoing and advances are being made. Cancer specialists use clinical trials to assess new treatments. Before any trial is allowed to take place, an ethics committee must have approved it and agreed that the trial is in the interest of the patients.
    You may be asked to take part in a clinical trial. Your doctor will discuss the treatment with you so that you have a full understanding of the trial and what it involves. You may decide not to take part, or to withdraw from a trial at any stage. You will still receive the best standard treatment available.

    Your feelings

    You may have many different emotions including anger, resentment, guilt, anxiety and fear. These are all normal reactions, and are part of the process many people go through in trying to come to terms with their condition.

    Everyone has their own way of coping with difficult situations. Some people find it helpful to talk to family or friends, while others prefer to seek help from people outside their situation. Some people prefer to keep their feelings to themselves. There is no right or wrong way to cope, but help is there if you need it. Our cancer support specialists can give you information about counselling in your area.

    References and thanks

    This information has been compiled using information from a number of reliable sources, including:
    • Clark, et al. Endocrine Tumours. 2003. B C Decker. Raghavan, et al. The Textbook of Uncommon Cancers. 3rd edition. 2006. Wiley.
    • Souhami, et al. Oxford Textbook of Oncology. 2nd edition. 2001. Oxford University Press.
    • UpToDate. www.uptodate.com (accessed September 2012).
    Thanks to Professor John Monson, Professor of Endocrinology, and the people affected by cancer who reviewed this edition. Reviewing information is just one of the ways you could help when you join our Cancer Voices network.

    Content last reviewed: 1 January 2013

    http://www.macmillan.org.uk/Cancerin...nalglands.aspx
    Lần sửa cuối bởi thanhthanh, ngày 23-02-2013 lúc 12:02 PM.

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