Acupuncture is a complementary form of therapy used in traditional Chinese medicine. A doctor inserts thin needles at precisely defined points on the body. This is supposed to loosen what are thought to be blockages in the body or to stimulate or calm different organs.

An adenoma is a benign growth in the top layer of tissue in a gland (eg the thyroid) or the mucus membrane lining the gastrointestinal tract (stomach and bowel). Although they are usually harmless, a cancer can develop out of an adenoma.

The Agency for Healthcare Research and Quality (AHRQ) is an agency of the US Department of Health and Human Services. Its mission is to improve the quality, safety, efficiency, and effectiveness of health care for all Americans. Information from AHRQ's research aims to help people make more informed decisions and to improve the quality of health care services. AHRQ was formerly known as the Agency for Health Care Policy and Research. You can read more about AHRQ at its website: www.ahrq.gov

An allergy is the body’s overly sensitive reaction to a foreign substance. The body produces antibodies just as it would if the substance were a germ, although it is not dangerous to the body. The symptoms of the allergy partly depend on the substance causing it, the allergen. People with allergies often have symptoms like running nose, watery eyes, itching, rashes, stomach and bowel problems or asthma. Typical allergens are pollen, animal hair, proteins in certain food or house dust mite excrement.

The air we breathe in goes through the voice box and then through the windpipe. The windpipe divides into the two main bronchi. Each of these main bronchi branches into smaller bronchi and bronchioles. At the end of the bronchioles, there are groups of tiny air sacs, which are called alveoli or pulmonary vesicles.

Anti-inflammatory drugs are drugs that reduce inflammation. This includes substances produced by the body itself like cortisone. It also includes artificial substances like ASA – acetylsalicylic acid (or “aspirin”) or ibuprofen –, which relieve pain and reduce fever as well as reducing inflammation.

Antibiotics are medicines that can be used for bacterial and some fungal infections. Antibiotics do not work against viruses. Well-known antibiotics include penicillin, tetracycline and chloramphenicole.

Antioxidants are substances that protect the body cells against harm caused by particular aggressive atoms or molecules called free radicals. Antioxidants attach themselves to the free radicals, and stop them doing harm to other cells. The most well-known antioxidants are vitamins.

Apnea (from the Greek apnoia, meaning “not breathing”) refers to a suspension of breathing. These breathing pauses can last anywhere from a few seconds to several minutes and result in falling blood oxygen levels. Possible causes are airways that have become blocked, for example by breathing in a foreign object or by the muscles in the back of the throat relaxing during sleep and then collapsing. Several unnoticed breathing pauses during the night are a typical sign of what is called sleep apnea. Sleeping pills, alcohol or carbon dioxide can also affect particular nerve cells that make up the brain’s breathing center and impair the body’s control over breathing.

Asthma (asthma bronchiale) is a permanent (chronic) disease with symptoms like coughing and breathlessness often occurring in acute attacks. In asthma, the airways are overly sensitive. The development of asthma is often associated with an overreaction to foreign substances or physical stimuli, frequently in connection with an allergy.

Atrial fibrillation is a type of arrhythmia where the heart’s atria (the chambers where blood enters the heart) beat very rapidly and irregularly. This is not usually acutely life-threatening, but with time it can increase the risk of having a stroke. This is due to small blood clots that are then more likely to occur in the atria because the normal flow of blood is affected.

Bacteria are micro-organisms that, unlike viruses, can exist on their own. Viruses, on the other hand, can only exist inside a living cell. Most bacteria are not harmful to people, and some are actually beneficial. Bowel bacteria support bowel health. However if they get into the urinary system, they can cause an infection there. Doctors prescribe antibiotics for illnesses where bacteria need to be stopped or killed off. Immunisation is also possible against some bacterial infections, such as diphtheria, tetanus or whooping cough.

Benzodiazepines are a large group of psychoactive drugs with a calming, anti-anxiety and anti-spastic effect. They are used as hypnotics and sedatives. Their effect lasts from several hours to several days. One of their major disadvantages is that they can become addictive even if used for a relatively short time.

Beta-carotene (or ß-carotene) is the colouring that makes some fruit and vegetables yellow or orange (like carrots). It is an early chemical stage of vitamin A, and this is why it is sometimes called pro-vitamin A. The food industry uses beta-carotene as a food colouring agent. It is also an ingredient in many multi-vitamin preparations.

Biofeedback is a relaxation technique from behavioral therapy. In biofeedback sensors measure body functions like pulse, breathing rate, body temperature, brain waves and muscle tension. A computer then makes it possible to see and hear these values. The next step is learning how to influence these values by reacting to them (a feedback loop), usually by relaxing.

The Body Mass Index (BMI) is a measurement used to assess body weight. It describes the relationship between a person’s weight and height and is calculated using the following formula: BMI = weight (kg) / height (m)2. For example, if you are 1.70 m tall and weigh 60 kg, you would calculate your BMI like this: 60 / (1.70 x 1.70) = 20.76. So this would mean that you have a BMI of around 21. People who have a BMI between 18.5 and 24.9 are considered to have a normal weight. A BMI below 18.5 is considered to be underweight, and a BMI between 25 and 29.9 is considered to be overweight. People who have a BMI over 30 are considered to be obese. The BMI only says something about people’s total body weight, though, and nothing about their body fat. Two people could have the same BMI but a different amount of fat in their bodies. So a bodybuilder who has a lot of muscle tissue and little fat could have the same BMI as a person who has little muscle tissue and a lot of fat. Still, a BMI over 30 is usually a sign of a high percentage of body fat.

Bowel polyps are benign growths in the mucus membrane lining the inside of the bowel. Cancer can sometimes develop in a bowel polyp.

Brain tumors are made up of cells that are growing abnormally in the brain. A brain tumor can be benign or malignant, and may have many symptoms: for example double vision, facial paralysis, unsteady walking, epileptic seizures, changes in personality, and unusual headaches or nausea. Since space inside the skull available for the brain is limited, even benign brain tumors can lead to serious symptoms because of the resulting pressure. On the other hand, someone can have a brain tumor and not have any symptoms for a long time.

Breathlessness, also called shortness of breath or dyspnoea, is when a person temporarily or permanently feels that they cannot get enough air when breathing. In severe breathlessness, people have a sensation of tightness or are even afraid of suffocating. Breathing is labored and it is difficult to breathe deeply. Breathlessness occurs in lung diseases like asthma or pneumonia, but also during a heart attack or in extreme obesity.

The air we breathe in enters the lungs through the windpipe. From there it is conducted through the branching structure of airways (bronchi), which become finer and finer, to the pulmonary vesicles (alveoli). The exchange between oxygen and carbon dioxide takes place in the alveoli.

Bronchitis is the inflammation of the airways, also called bronchi. The usual symptom is that phlegm is coughed up almost daily over a longer period of time. Bronchitis can be acute (temporary) or chronic (permanent).

A bypass is an artificially created passageway that forms an alternative to a narrowed path, for instance in a blood vessel. This technique can be used for narrowed or blocked coronary arteries or leg arteries, for example. The bypass creates a new connection around the narrowed path, making it possible for enough blood to flow. Either the body’s own veins or arteries, or bypasses made of artificial tissue can be used to create this passageway. The artificial tissue may be made of Gore-Tex or Teflon.

Calcium is an important mineral for human health. It is one of the building blocks for bones and teeth, and it is necessary for blood clotting, the muscles and the nerves. Calcium occurs in milk and milk products, as well as in green leafy vegetables. People can get a calcium deficiency if they have a chronic inflammatory bowel disease, as well as in pregnancy or during breastfeeding.

Heart or cardiac pacemakers are small electronic devices implanted under the skin. They are connected to the heart by special wires. Pacemakers measure whether or not the heart is beating regularly and at the right speed or pace. They use electrical impulses to get the heartbeat back into normal rhythm if there is a problem.

When the natural lens of the eye becomes cloudy or completely opaque, this is called a cataract. Cataracts interfere with sight, and can eventually cause complete vision loss if left untreated. Cataracts can be surgically removed. The function of the eye lens is then replaced with an artificial lens.

Catheter is the medical term for a thin tube inserted into a body cavity that usually remains there for a longer period of time. Medication catheters can be used to administer painkillers or anesthetics in specific parts of the body, for example. Other catheters may be used for letting fluids out of the body.

Cholesterol levels are a way of measuring the concentration of cholesterol in the blood. It is often called fat levels, although cholesterol is not really a fat. Fat is found in the tiny droplets that transport cholesterol through the blood. Depending on the type of transport molecule, doctors differentiate between HDL, LDL and VLDL cholesterol. The total level of cholesterol, measured in milligrams per decilitre (mg/dl), combines the individual values of all these types of cholesterol.

The Cochrane Collaboration is an international network of thousands of researchers and others. They work together in teams called Cochrane Review Groups to answer questions about health care by doing systematic reviews of evidence. To achieve this, the members of the Collaboration have developed systems and methods for systematically finding and analysing the results of trials of health care interventions. The goal of the Cochrane Collaboration is to help patients, health care practitioners and others make more informed decisions about health care. You can read more about the Cochrane Collaboration at their website.

"Colla" comes from a Greek word meaning glue. Collagen is a protein that is part of a variety of tissues. For example, there is collagen in connective tissue, tendons, ligaments, cartilage, bones, and in dentine in the teeth.

The colon is the main part of the bowel or intestines. It includes the appendix. The term colon is often used instead of the term large bowel. Stools are developed in the colon, where the fluids and mineral salts are also removed from the remaining foodstuffs that have reached the bowel. At the same time the colon produces mucus, which helps make it easier to empty the bowels.

Colorectal cancer is cancer in the large bowel (including the colon) and/or the rectum. “Colo” stands for the colon, and “rectal” for the rectum. Colorectal cancer is one of the most common forms of cancer.

Computed tomography, or CT for short, is a special x-ray examination (the ancient Greek tome means “slice”, and Greek graphein means “to write”). The person being examined lies down and is then moved through a ring-shaped CT scanner. An x-ray source in the CT scanner rotates around the selected body region and its density is measured from various directions. A computer puts this data together and generates a multidimensional cross-sectional image of the body region examined. As in any other x-ray examination, people who have a CT examination are exposed to radiation.

In chronic obstructive pulmonary disease (COPD), the airways are permanently narrowed and the lungs are damaged. COPD is not the same as asthma – but both diseases can occur at the same time.

The cornea is the transparent outer surface of the eye. It protects the eye from foreign bodies. Fluid from the tear ducts keeps the cornea moist.

Corneal abrasions are superficial injuries of the eye’s cornea. They normally heal on their own within one to two days. These scratches are often caused by foreign objects that get stuck under an eyelid, for example.

COX-2 inhibitors are a class of anti-inflammatory drugs that relieve pain and reduce fever. They first came onto the market at the end of the 1990s.

CPAP stands for “continuous positive airway pressure”. CPAP therapy involves pumping mildly pressurized air through a mask and into the airways during sleep. It is used in treating temporary nighttime breathing pauses. The incoming air prevents the muscles in the back of the throat from collapsing and blocking the upper airways. While this kind of CPAP therapy is about stabilizing the relaxed muscles in the back of the throat with mildly pressurized air, CPAP ventilation is also used in intensive care or by emergency medical services for people with lung or heart disease. In this case, the mild pressure makes it easier to breathe in, making sure that more air flows into the lungs.

Crohn’s disease is one of two similar forms of chronic inflammatory disease. The other is ulcerative colitis. Crohn’s disease usually affects the small bowel, and rarely, the large bowel. There are times of symptom-free remission, but also active periods with pain in the abdomen, diarrhoea and weight loss that can be so severe that people cannot go to work or undertake their daily activities. Attacks can be so severe that people need to go to hospital.

The word debridement comes from the French word "débrider", which means to remove extra fluid. In medicine, debridement is the cleaning or scraping away of dead cells and contaminated tissue out of a wound. This can be done with a scalpel, spoon or other instrument, and is called surgical debridement. It can also be done with a chemical made of particular proteins (enzymes), or it can be done "mechanically".

"Mechanical" or physical debridement can be done with a special dressing. Excess wound fluid, cells, and germs stick to the dressing and are removed whenever the dressing is changed. Mechanical cleaning of a wound can also be done under the shower: the flow of water can remove germs and dead cells. Using wound-cleaning substances like hydrogen peroxide or moist dressings is another form of mechanical debridement.

An old type of debridement that is coming more into use again is "biological" debridement, done with sterile maggots.

The term debridement is also used for the surgical removal of stitches after a wound has healed.

The word decubitus comes from the Latin word "decumbere", which means to lie down. It is usually called a bed sore, pressure sore or pressure ulcer. Bed sores develop from unrelieved pressure on the skin, causing damage to the skin and the underlying skin tissue. The continuous pressure compresses small blood vessels, which cannot supply the surrounding tissue with enough oxygen and nutrients. The skin changes and becomes necrotic (dies). Bed sores mainly affect people who have to lie in bed for long periods. The most vulnerable areas are those where the skin lies directly over the bone, and include the heels, ankles, knees, hips, base of the spine, spine, and elbows. Elderly people or people with chronic diseases such as diabetes or circulation problems have a high risk of developing bed sores.

Deoxyribonucleic acid (DNA) is a large molecule containing human genetic information. It is made up of different bases, phosphate and sugar. The molecule has two strands, which are connected to each other like a ladder and entwine to form a helix. The DNA is part of the chromosomes in the cell nucleuses of the body. It stores genetic information, which is needed to produce new cells, for example.

Depression is one of the most common mental illnesses, and it can be mild, moderate or serious. There are several different types of depression that can be recognised by different signs. Which symptoms of depression occur and how strong and frequent they are vary from person to person. People in any social or age group can be affected, both women and men. If someone has had at least two of the following symptoms for longer than two weeks, it might mean that they are depressed: deep sadness; listlessness; loss of interest in the things they usually care about.

The term diagnosis (from the Greek word diagnosi: “distinguishing”) is used to mean the identification and naming of an illness or a disease. A diagnosis is usually made by evaluating the medical history, symptoms and test results. The tests include both comprehensive physical examination and blood tests or examinations using medical instruments such as ultrasound or x-ray.

Dietary supplements (also known as food supplements or nutritional supplements) are concentrated vitamins, minerals, trace elements, fibers and/or other substances that are intended to supplement the diet. Advocates of dietary supplements claim that they have a certain, often preventive or strengthening effect on the body. They are available as capsules, pills, powder or ampules, for example. From a legal point of view, dietary supplements rank among foods and therefore – as opposed to medications – do not need official approval. More information is available on the website of the German Federal Institute for Risk Assessment (Bundesinstitut für Risikobewertung, BfR): To the BfR website (in English)

Drusen are deposits of tissue in the retina. They are made of dead cells that are the by-products of metabolism in the eye.

Eczema is a collective term referring to all non-infectious acute or chronic inflammations of the skin with itching. The symptoms can occur locally on the skin or on the entire body and may include redness, blistering, nodules or crusting.

In emphysema, air is found in a part of the body where it is not supposed to be, or there is an unusual quantity of air in a particular part of the body. One well-known emphysema is pulmonary emphysema. In pulmonary emphysema, the alveoli are destroyed. Air breathed in cannot be fully exchanged, so it builds up in the lungs.

With an endoscope, a doctor can look inside parts of the body that have openings, like the bowel, lungs, vagina or bladder. Endoscopes usually have a little light and a camera. Depending on the type of examination, an endoscope could be a short, stiff pipe that enables inspection of the bladder or vagina. Or it can be a long flexible tube that can be inserted into, for example, the stomach or bowel.

Evidence is what we call scientific proof from well-conducted, good-quality scientific trials that have been carefully designed to answer specific questions. Depending on the types of questions, different scientific research methods (types of study) are most appropriate to find reliable answers to these questions. Randomized controlled trials (RCTs), for example, are the best way to get reliable evidence on the effectiveness of medical treatments (interventions). This type of study, however, is not the best form of evidence for all possible questions, and does not provide the best answers to all kinds of questions, either. Epidemiological studies, for example, are very suitable for establishing well-founded proof for the spreading of a disease in the population.

Familial adenomatous polyposis (FAP) is an inherited disease that affects the large bowel (colon) and rectum. People with FAP will develop a large number of polyps at an early age. There is a high chance that bowel cancer might develop in some of them.

Fatigue is a term used to describe paralyzing mental and physical exhaustion that may also be accompanied by heightened emotional sensitivity. In contrast to usual tiredness, fatigue only responds to rest or sleep to a very limited extent.

Fertility is the ability to conceive a child (men and women) and carry the child to full term (women). A woman’s fertile phase of life usually begins when she has her first period (menarche) and ends after her last period (menopause). Men are usually able to father children from puberty until old age. In women, infertility means the inability to carry a pregnancy to full term.

In dentistry, a fissure is a term for the pits, dents and grooves in the chewing surfaces of the molars or back teeth. In medicine generally, a fissure is a natural groove or crevice in the surface of an organ, as well as a tear through injury (a hairline fracture in a bone, for example).

Fluoride is a naturally occurring substance. It is used in toothpaste and table salt as a preventive measure against tooth decay (caries or cavities). If children get too much fluoride, it can affect the development of the tooth enamel, causing white patches on the teeth. This is toothpastes made for children have less fluoride than toothpastes for adults.

Folic acid is a water-soluble vitamin. Green and leafy vegetables (eg lettuce, spinach and broccoli), liver, egg yolk, and particularly wheatgerm are rich sources of folic acid. Having too little of this vitamin can lead to anaemia. In pregnancy, low levels of folic acid can increase the risk of a fetal abnormality called spina bifida. This is why women who are pregnant, or trying to get pregnant, are encouraged to increase their intake of folic acid.

Foot reflexology massage is based on the idea that certain zones on the foot are connected to particular regions of the body or specific organs by energy lines, for example the big toe being associated with the head. Massaging these zones aims to relieve symptoms in the corresponding organs and parts of the body.

Gingivitis is the medical term for gum inflammation. Signs are swelling, reddening or bleeding in the area near the edges of the gums. Plaque building up near the gums is often a cause of gingivitis, because bacteria grow in plaque.

Glaucoma is a condition that can lead to vision loss. The normal fluid pressure rises inside the eye, and this can damage the optic nerve.