Online Medical Dictionary

Letter G

G: Guanine; member of the base pair guanine-cytosine (G-C) found in DNA.
GAD: Abbreviation for generalized anxiety disorder.
Galactorrhea: Lactation occurring at any time other time than while nursing. can sometimes be the cause of conditions relating to the kidneys.
Galactose: A milk sugar composing half of lactose.
Galactosemia: A rare, inherited metabolic condition, affecting the body's ability to metabolize the sugar galactose; a separate disorder from lactose intolerance.
Galeophobia: An abnormal fear of sharks.
Gallbladder: The small organ that functions to store bile secreted by the liver and aid in the process of digestion.
Gallbladder Absence: Agenesis of the gallbladder; the failure of the gallbladder to develop, occurring in association with other malformations such as atresia of the bile ducts or renal agenesis (failure of a kidney to develop). Occurs in roughly one in one thousand people, and when isolated is not health affecting.
Gallstone Pancreatitis: Pancreatitis induced by the presence of gallstones.
Gallstones: Concretion of bile in the gallbladder, causing the formation of-stone like components. Cholesterol is the greatest contributor to the formation of gallstones, which can also make their way into the biliary tract.
GALT
GALT Deficiency: Lack of the enzyme galactose-1-phosphate uridyl transferase (GALT) causing the genetic metabolic disease galactosemia. Galactosemia can be fatal if undetected, but treatable with the avoidance of galactose in the diet.
Gamete: The sperm or ova; a cell that fuses with another cell during the process of sexually generated fertilization.
Gametic: Regarding the gamete, the sperm or ova.
Gametophobia: An abnormal fear of marriage.
Gamma Knife: A one-day radiation therapy used to treat brain tumours, wherein the Gamma Knife device focuses several low-dosage gamma radiation rays directly on the target tumour,relatively sparing surrounding areas from exposure to radiation.
Gamma Ray: High-frequency electromagnetic radiation produced by the interactions of some subatomic particles. While gamma rays can be used beneficially in CT scans, radiation therapy, gamma surgery and nuclear medicine, they can also cause cancer. The ionizing radiation produced by gamma rays can break DNA strands, thereby destroying the genetic information stored by a cell.
Ganglion: A mass of tissue or nerve cell bodies.
Gangrene: The death of cells resulting from the lack of blood flow to an area of tissue, due to an infection, injury or health condition that impedes circulation. Gangrene can be treated with antibiotics, maggot therapy, surgery, or in extreme cases, amputation.
Gastrectomy: Surgergical removal of all or a portion of the stomach.
Gastric: Pertaining to the stomach.
Gastric Atrophy: Weakening of the stomach muscle, resulting in a lessened production of gastric digestive juices.
Gastric Banding: The surgical placement of a band around the top portion of an individual's stomach, limiting the amount of food the stomach can comfortably take in and store, as a method of treating obesity.
Gastric Cancer: Stomach cancer; the bacterium Helicobacter pylori is believed to be responsible in most cases. Stomach cancer often spreads to surrounding organs, and can begin in any gastric area.
Gastric Stapling: A surgical procedure wherein the upper portion of the stomach is stapled to form a small pouch, limiting the amount of food the individual can take in, as a method of treating obesity.
Gastric Ulcer: A peptic ulcer; usually associated with the gastric dwelling bacterium Helicobacter pylori. Most peptic ulcers develop in the small intestine, not the stomach itself. The bacterium must be treated with antibiotics or other methods in order for the ulcer and its painful effects to subside.
Gastritis: Inflammation of the stomach organ.
Gastroenteritis: Inflammation of the stomach and the intestines, which can be induced by stress, bacteria or virus.
Gastroenterologic Disease: Any disease pertaining to the digestive system. This encompasses Celiac disease, diverticulosis, Crohn's disease, Barrett's esophagus, cirrhosis of the liver, colon polyps, colon cancer and bile duct disease.
Gastroenterologist: A physician specializing in the diagnosis and treatment of disorders relating to the gastrointestinal tract. The gastrointestinal tract includes the esophagus, stomach, small intestine, large intestine, pancreas, gallbladder and liver.
Gastrointestinal: Pertaining to the stomach, small intestine and large intestine.
Gastrointestinal Stromal Tumour (GIST): A benign or malignant tumour, usually developing out of the wall tissue of the gastrointestinal tract, accounting for less than five per cent of known gatrointestinal cancers.
Gastrointestinal Tract: Though sometimes referring only to the stomach and intestines, the gastrointestinal tract, or GI tract, can include all structures from the mouth to the anus, including the esophagus, stomach, duodenum, colon and rectum.
Gastroparesis: Failure of the stomach muscle to be able to contract normally, thereby keeping food in the stomach for longer durations than necessary, potentially resulting from damage to the vagus nerve. Symptoms may include stomach bloating, nausea and vomiting.
Gastropathy: Disease of the stomach.
Gastroscope: An instrument administered through the mouth used to view the stomach and provide biopsy.
Gastrostomy: An opening in the stomach made surgically.
Gelineau Syndrome: Narcolepsy; a neurological disorder characterized by an urgent and uncontrollable need to sleep.
Gene: The segment of DNA holding the information necessary for human heredity.
Gene Deletion: A mutation that causes the deletion of a chromosome or segment of DNA, responsible for many genetic conditions, diseases, including Duchenne muscular dystrophy, and the development of some cancers. Large deletions may result in fatality.
Gene Duplication: Any copy made of a segment of DNA containing a gene. This can include duplication that occurs as a result of an error, a complete copy of an entire chromosome, or a retrotranspositional event. Duplications of oncogenes are a common cause of malignancies such as breast cancer. Also termed gene amplification or chromosomal duplication.
Gene Mapping: The process of developing a genetic map, wherein DNA fragments are assigned to chromosomes. Breeding experimentation and pedigree analysis are techniques used to determine genome sequencing features. Also termed genome mapping.
General Paresis: A syphilis-induced paralysis and dementia, caused by chronic inflammation affecting the brain and central nervous system. Also called paralytic dementia.
Genetic Anticipation: A phenomenon in which a genetic condition takes an earlier and more apparent onset with each succeeding generation. Common in repeat disorders including myotonic dystrophy and Huntington's disease.
Genetic Code: The instructions encoded in genetic material by which DNA or mRNA sequences are translated into specific proteins by cells.
Genetics: The study of heredity.
Genitalia: The reproductive organs of the male and female.
Genome: The entirety of genetic, hereditary information, coded in DNA or RNA, for an organism.
Gerascophobia: An abnormal fear of growing older.
Geriatrics: The branch of medicine concentrated on the diagnosis, treatment and prevention of disease for aging peoples.
Germinoma: A germ cell tumour.
Gestation Period: The time period occurring from conception to birth. Normally this equates nine months.
Gingivitis: Gum inflammation caused by the bacterium commonly referred to as plaque, which adheres to the surface of teeth.
Gland: A group of cells that secrete for use or remove from circulation a substance in the body.
Glaucoma: A disease often, but not in every case, affected by fluid pressure in the eye. Pressure can be relieved with medication. The optic nerve is damaged, which can lead to irreparable loss of vision. Glaucoma can be treated, though not cured, with laser eye surgery and other operations.
Glioma: A tumour developing from glial cells in the brain or spinal cord. Malignant gliomas can be treated with radiation therapy and chemotherapy, but prognosis is poor. Roughly half of those diagnosed with cancerous, high-grade (undifferentiated) gliomas face mortality within the first year of diagnosis.
Glucosamine: An amino sugar and abundant monosaccharide (the most basic unit of a carbohydrate, or simplest for of sugar). Used alternatively to treat the symptoms associated with osteoarthritis.
Glucose: A monosaccharide capable of adopting many structures. Also termed dextrose. Glucose is paramount in providing biological fuel for the body and brain functioning. Low glucose levels can impede mental processing. Insulin is the regulator for glucose levels in the blood.
Gluten: A protein composite commonly found in cereal grains such wheat, rye and barley. Gluten can incite an adverse reaction in those with Celiacs disease or a wheat allergy.
Goiter: An enlarged thyroid gland.
Gonad: An organ that produces gametes. In females the gonads are the ovaries, while in males functioning gonads are the testicles.
Gonarthritis: Inflammation of the knee joint.
Gonorrhea: A sexually transmitted infection (STI) or infection transmitted at birth, caused by the bacterium Neisseria gonorrhoea.
Gout: A condition marked by recurring attacks of joint inflammation, or arthritis, incited by heightened levels of uric acid in the blood, which crystallize and form deposits in the joints or tendons. Most commonly gout affects the joint at the big toe, but may also manifest as kidney stones or tophi.
Graft: The transfer of healthy skin, bone or other tissue from one part of the body to an area of the body where diseased or injured tissue has been removed and needs be replaced.
Graves' Disease: An autoimmune disease marked by the hyperactivity of the thyroid gland, causing the over production of thyroid hormones and the enlarging of the thyroid gland into a goiter. Graves' disease causes hyperthyroidism or thyrotoxicosis, a metabolic imbalance which can induce both neuropsychological and physical symptoms.
Growth Hormone: A peptide, protein-based hormone, also called somatropin, which stimulates growth through cell production and regeneration.
Gustavson Syndrome: An X-linked syndrome causing severe mental retardation as well as marked physical impairments and restrictions.
Gymnophobia: An abnormal fear of nudity.
Gynecologic Oncologist: A physician specializing in the diagnosis, treatment and prevention of cancers of the female reproductive organs.
Gynecologist: A physician specializing in the diagnosis and treatment of diseases ofthe female reproductive organs.
Gynecology: The branch of medicine focused in the health and disesase of the female reproduction organs.
Gynephobia: An abnormal fear of women.