Dictionary

Body systems

Anatomy and the conditions of each body system, from the heart and lungs to the skin.

GABAGamma-aminobutyric acid: the brain's main calming (inhibitory) neurotransmitter.

gallbladderA small pear-shaped sac under the liver that stores bile and releases it to help digest fat.

gallstoneA hard, pebble-like lump that forms in the gallbladder from substances in bile.

ganglionA cluster of nerve cell bodies outside the brain and spinal cord; plural ganglia.

gangreneThe death of body tissue because its blood supply has been lost or because of severe infection.

gas exchangeThe movement of oxygen from the air sacs of the lungs into the blood and of carbon dioxide from the blood into the air sacs.

gastricRelating to the stomach.

gastritisInflammation of the lining of the stomach.

gastroenteritisInflammation of the stomach and intestines.

gastroesophageal refluxThe backward flow of stomach contents up into the esophagus.

gastroesophageal reflux diseaseA long-term condition in which stomach contents, including acid, flow back up into the esophagus.

gastrointestinalHaving to do with the stomach and intestines, or with the whole digestive tract from the mouth to the anus.

gastrointestinal tractThe long tube that food passes through, from the mouth to the anus.

generalized anxiety disorderAn anxiety disorder in which a person feels excessive, hard-to-control worry about many everyday things for at least six months.

genitalRelating to the sex organs, especially the outer ones.

genital wartA small, soft growth on or around the genitals or anus caused by certain types of human papillomavirus (HPV).

genitaliaThe reproductive organs, especially the external sex organs.

genitourinaryRelating to the genital (reproductive) organs and the urinary organs together.

gestationThe time a baby develops in the uterus, from conception to birth; pregnancy.

gestational diabetesHigh blood sugar that first develops during pregnancy in a person who did not have diabetes before.

gestational hypertensionHigh blood pressure that starts after 20 weeks of pregnancy in a person whose blood pressure was normal before.

gingivaThe gums: the firm pink tissue that covers the jawbone and surrounds the base of the teeth.

gingivitisInflammation of the gums.

glandAn organ or group of cells that makes and releases a substance the body uses, such as a hormone, sweat or saliva.

Glasgow Coma ScaleA scoring tool that rates a person's level of consciousness by their eye opening, verbal response and movement, from 3 to 15.

glaucomaAn eye disease in which the optic nerve is damaged, usually with raised pressure inside the eye, leading to loss of vision.

glomerularRelating to the glomerulus, the tiny cluster of capillaries in each nephron of the kidney that filters the blood.

glomerular filtrationThe first step in making urine, when the kidneys' tiny filters let water and small substances pass out of the blood.

glomerular filtration rateHow much blood the kidneys filter each minute, used as the main measure of kidney function.

glomerulonephritisInflammation of the glomeruli, the tiny filtering units of the kidneys.

glomerulusA tiny ball of capillaries in the kidney that filters the blood as the first step in making urine.

gluconeogenesisThe making of new glucose by the body from substances that are not carbohydrates, such as protein and fat.

glucoseA simple sugar that is the body's main source of energy.

glutamateThe main chemical messenger in the brain that excites nerve cells, making them more likely to fire.

glycogenThe stored form of glucose, kept mainly in the liver and muscles.

glycolysisThe first stage of breaking down glucose inside a cell to release energy.

goiterAn enlarged thyroid gland, seen or felt as a swelling at the front of the neck.

gonadA sex gland: an ovary or a testis, which makes eggs or sperm and sex hormones.

gonorrheaA bacterial infection, spread mainly through sex, caused by Neisseria gonorrhoeae.

Goodell signSoftening of the cervix felt in early pregnancy.

goutA form of arthritis in which crystals of uric acid collect in and around a joint.

granulation tissueNew, moist, red tissue that fills a healing wound from the bottom up.

Graves diseaseAn autoimmune disease in which antibodies make the thyroid gland overactive.

gravidaA pregnant woman; in a pregnancy history, the number of times a person has been pregnant, including now.

gray matterNerve tissue made mostly of nerve cell bodies, found on the outer layer of the brain and in the center of the spinal cord.

groinThe area where the upper thigh meets the lower belly, on each side.

growth and developmentThe changes in body size (growth) and in skills and abilities (development) that happen across a person's life.

growth hormoneA hormone from the pituitary gland that drives growth in children and helps control body build and metabolism in adults.

Guillain-Barre syndromeA rare autoimmune disorder in which the immune system attacks the nerves outside the brain and spinal cord.