galvanic fuel cell an electrical analyzer that measures gas concentrations by measuring the change in resistance to electrical current in reference and sampling circuits.

galvanometer a sensitive measuring instrument designed to provide a response to the effects of an electrical current.

gap junction a structure within the intercalated disks located at the junctions of the branches of myocardial cells, permitting very rapid conduction of electrical impulses from one cell to another.

gangrene death of tissue caused by a decrease or absence of blood supply

gas a fluid state of matter with the least organization and definition.

gas gangrene tissue necrosis with gas bubbles in soft tissue after trauma or surgery, caused by anaerobic organisms and exhibiting a rapid rate of progression.

gastrectomy surgical removal of the stomach  

gastric distention swelling or extension of the stomach gastrointestinal of or pertaining to the organs of the gastrointestinal tract, from mouth to anus

gastric tonometry technique that measures CO2 in the gastric lumen using a catheter placed in the stomach.

gastrointestinal tract the route taken by food from the stomach to the rectum.  

gastroscopy visual examination of the stomach using a gastroscope

Gay-Lussac's law proportional relationship of pressure and temperature at a constant volume and mass.

generation the process of forming a new organism or part of an organism.

gestation the period of time from the fertilization of the ovum until birth.

geometric standard deviation (GSD) measure of the magnitude of variation in particle size distribution-for example, a monodisperse aerosol in which all particles are basically the same size has a GSD < 1.2, whereas a heterodisperse aerosol, with a wider range of particle sizes, has a GSD > 1.2.

gestational age age of a fetus or a newborn, dating from the first day of the mother's last menstrual period; usually expressed in weeks.

giemsa stain a process of staining bacteria for identification

globin the protein component of hemoglobin

glomerulonephritis inflammation of the glomerulus in the nephron of the kidney.

glomerulosclerosis hardening of the renal glomerulus

glomerulus a tuft or cluster; a structure composed of blood vessels or nerve fibers, such as a renal glomerulus.

glossopharyngeal of or pertaining to the tongue and pharynx

glossopharyngeal breathing also known as "frog breathing," a technique involving the use of oropharyngeal muscles to inject air into the trachea and thus augment ventilation to provide short periods of spontaneous ventilation, to improve effective cough, and to increase the volume of the voice.

glossopharyngeal nerve the 9th cranial nerve.

glottis the variable opening between the vocal cords

glucocorticoid an adrenocortical steroid hormone that increases glyconeogenesis, exerts an antiinflammatory effect, and influences many body functions

glucose six-carbon sugar with the formula of C6H1206; found in fruits and other foods; primary source of energy for cells.

glutaraldehyde a high level disinfectant solution that can also be used as a sterilant

glycolysis anaerobic process necessary to glucose metabolism that begins with the breakdown of a six-carbon glucose chain (C6H1206) to two three-carbon pyruvate (pyruvic acid) molecules in the cytosol of the cell; prepares glucose for the second step in catabolism, the citric acid cycle

glycoprotein any of a class of conjugated proteins consisting of a compound of a protein with a carbohydrate group.

glycoprotein (GP) receptors adhesive glycoproteins located on platelet surface that bind with various components of connective tissue and blood to form thrombi. The major receptors and their function include the following:

GP la binds the platelets directly to collagen fibers present in connective tissue.

GP lb binds the platelets to von Willebrand factor (vWF). GP IIb/IIIa binds the platelets to vWF and, after the platelets are activated, to fibrinogen.

Goals in the management of an acute MI the three major goals in the management of acute MI are:

• Prevent the further expansion of the original thrombus and/or prevent the formation of a new thrombus

• Dissolve or lyse the existing thrombus (thrombolysis)

• Enlarge the lumen of the occluded section of the affected coronary artery

goblet cells mucus producing cells, shaped like goblets, found among the epithelial cells lining the airways goiter a hypertrophic thyroid gland associated with abnormal thyroid function

Goodpasture's syndrome a chronic relapsing pulmonary hemosiderosis, usually associated with glomerulonephritis and characterized by a cough with hemoptysis, dyspnea, anemia, and progressive renal failure

gradient a slope or grade; a difference in values between two points.

Graham's law the law stating that the rate of diffusion of a gas through a liquid (or the alveolar-capillary membrane) is directly proportional to its solubility coefficient and inversely proportional to the square root of its density

gram metric standard of weight, equal to the weight of 1 ml of water at 4° C (its maximum density).

Gram's stain test that stains microorganisms with crystal violet dye, followed by an iodine solution, decolorizing, and then counterstaining with safranin. The retention of either the violet color of the stain or the pink color of the counterstain serves as a primary means of identifying and classifying bacteria by revealing details of the cell wall structure.

gram molecular weight (gmw) a chemical measurement for the mass of the chemical equal to the atomic weight of its chemical components expressed in grams; sometimes known as the combining weight.

gram-negative bacteria bacteria that have a cell wall composed of a thin layer of peptidoglycan covered by an outer membrane of lipoprotein and lipopolysaccharide and which lose the stain or are decolorized by alcohol in Gram's stains; examples include the following: Haemophilus influenzae, Moraxella catarrhalis, Pseudomonas aeruginosa, Klebsiella species, Escherichia coli, Enterobacter species, Serratia species, Acinetobacter species, and Proteus mirabilis.

gram-positive bacteria bacteria whose cell walls are composed of a thick layer of peptidoglycan with attached teichoic acids and which retain the stain or resist decolorization by alcohol in Gram's staining; examples include the following: Streptococcus pneumoniae, Staphylococcus aureus, and Enterococcus species.

granulocyte a type of leukocyte characterized by the presence of cytoplasmic granules.

granulocytopenia an abnormal condition of the blood, characterized by a decrease in the total number of granulocytes

granuloma a circumscribed mass of cells (mainly histiocytes) normally associated with the presence of chronic infection or inflammation

granulomatous composed of or having the characteristics of a granuloma

gravida a combining form indicating number of pregnancies, for example, gravida 2 indicates two pregnancies

gravity dependent a phrase used to describe the natural tendency of blood, which is a relatively heavy substance, to move to the portion of the body, or portion of the organ, that is closest to the ground.

ground electrode the ECG lead other than the positive and negative leads that grounds the input to prevent extraneous noise from entering the amplifier circuit.

group beating repetitive sequence of two or more consecutive beats followed by a dropped beat as seen in second­degree AV block.

group beats occurrence of two or more consecutive atrial, junctional, or ventricular premature contractions preceded and followed by the underlying rhythm.

gruel the semiliquid, lipid-rich mixture often seen within the atherosclerotic plaque.

grunting abnormal short, deep hoarse sounds in exhalation. The grunt occurs because the glottis briefly stops the flow of air, increasing intrapulmonary pressure. Grunting is most common in RDS infants where it probably helps prevent alveolar collapse

Guillain-Barre syndrome (GBS) acute idiopathic polyneuritis usually presenting as an ascending symmetrical paralysis of the lower extremities associated with absent tendon reflexes.

Guthrie test a test to detect phenylketonuria