G-H

Gadolinium

An intravenous contrast agent used with magnetic resonance imaging.

Gallstone (cholelithiasis)

A solid formation in the gallbladder or bile duct composed of cholesterol and bile salts.

γ-Aminobutyric acid (GABA)

An inhibitory neurotransmitter.

Gamma knife

A type of radiosurgery machine that focuses low-dosage gamma radiation on a precise target.

Gastric bypass

A surgical procedure for weight loss that elicits effectiveness through malabsorption and gastric volume limitation.

Gastritis

Inflammation of stomach lining.

Gastroparesis

A form of autonomic neuropathy involving nerves of the stomach, causing nausea, vomiting, and fluctuating blood sugars.

Gastrostomy

Operative placement of a new opening into the stomach associated with feeding tube placement.

Generalized seizures

A seizure where the entire cerebral cortex is involved from the onset.

Geniculate nucleus

The part of the brain that processes visual information from the optic nerve.

Genotype

The genetic constitution of an individual.

Geriatric syndrome

Age-specific presentations including visual and hearing impairment, malnutrition, and gait impairment commonly seen in older patients.

Gleason score

A system of histological grading used in prostate cancer, combining two highest scores for a total score from 2 to 10.

Glomerular filtration rate (GFR)

The volume of plasma filtered by the glomeruli per unit time, indicating overall renal function.

Glomerulonephritis

Inflammation of the capillary loops of the glomerulus, causing lesions and possible kidney function loss.

Glucagon

Hormone produced by the pancreas that raises blood glucose levels by converting glycogen to glucose.

Gluconeogenesis

Formation of glucose from non-carbohydrate precursors, primarily in the liver and kidney.

Glucosuria

Presence of glucose in the urine.

Glutamate

An excitatory amino acid found in the central nervous system.

Glycogenolysis

The process by which glycogen is broken down to glucose.

Goiter

An enlargement of the thyroid gland, causing a swelling in the front of the neck.

Gonioscopy

Examination of the anterior chamber angle using a gonioprism or Goldman lens.

Graft-versus-host disease

A condition resulting from donor immune cells attacking the normal tissue of a stem cell transplant recipient.

Graft-versus-tumor effect

An immune response directed at a patient’s malignant cells resulting from donor immune cell activation.

Grandiosity

Exaggerated sense of self-importance, ideas, plans, or abilities.

Granuloma

An organized collection of macrophages designed to wall off a foreign body or infectious pathogen.

Gummatous

A small, soft swelling characteristic of the late stages of syphilis, occurring in connective tissues.

Gut-associated lymphoid tissue

Lymphoid tissue, including Peyer patches, important for localized immunity in the gut.

Guttate psoriasis

Characterized by teardrop-like lesions, often on the trunk and proximal extremities.

Gynecomastia

Excessive development of breasts in males.

HACEK

Group of fastidious gram-negative bacteria associated with human infections.

Hashimoto Disease

An autoimmune condition where the immune system attacks the thyroid gland, potentially leading to hypothyroidism.

Health literacy

The capacity to obtain, process, and understand basic health information needed to make health decisions.

Heberden nodes

Hard, bony enlargement of the distal interphalangeal joint of a finger or toe.

Hematemesis

Vomiting blood from gastric or esophageal bleeding.

Hematochezia

Passage of bright red or maroon stool, indicating bleeding from the lower gastrointestinal tract.

Hematogenous

Spread of infection via the bloodstream.

Hematoma

Localized swelling filled with clotted blood due to a break in a blood vessel wall.

Hemiparesis

Weakness on one side of the body.

Hemisensory deficit

Loss of sensation on one side of the body.

Hemithorax

A single side of the trunk where the heart and lungs are located.

Hemoptysis

Expectoration of blood or blood-tinged sputum from the respiratory tract.

Heparin-induced thrombocytopenia

A syndrome resulting from the immune response against heparin-platelet complexes, leading to thrombotic events.

Hepatic encephalopathy

Confusion and disorientation in patients with advanced liver disease due to ammonia buildup.

Hepatic steatosis

Accumulation of fat in the liver.

Hepatocellular carcinoma

Cancer of the liver.

Hepatorenal syndrome

Acute kidney injury in individuals with liver disease due to renal blood flow reduction.

Hepatotoxicity

Toxicity to the liver causing cellular damage.

Herd immunity

Resistance to disease spread when a high proportion of the population is immune.

Herniation

Abnormal protrusion of an organ through a defect or opening in surrounding structures.

Hesitancy

A decrease in urine stream force, often due to obstruction.

Heteroreceptor

A site on a neuron that binds a neurotransmitter other than the one it releases.

Heterotopic

Placing a transplanted organ in an abnormal anatomical location.

Heterozygous

Having different alleles at a gene locus.

Hiatal hernia

Protrusion of part of the stomach through the diaphragm.

Hirsutism

Excessive body and facial hair, particularly in females.

Histocompatibility

Having antigenic similarities that prevent transplant rejection.

Homeostenosis

Impaired capability to withstand stressors and maintain homeostasis, often seen in elderly.

Homozygous

Having identical alleles at a gene locus.

Hormone receptor-positive

Expression of estrogen and/or progesterone receptors in breast cancer cells.

Hot flashes

A feeling of warmth commonly accompanied by skin flushing and perspiration.

Human epidermal growth factor receptor type 2 (HER2)-positive

Tumor positivity defined by specific staining characteristics in breast cancer.

Human leukocyte antigens (HLA)

Genes that contain proteins that help the body distinguish self from non-self cells.

Humoral

Relating to body fluids, particularly immune responses involving antibodies.

Hydrocephalus

A condition marked by excess cerebrospinal fluid in the brain, causing increased pressure.

Hydronephrosis

Swelling of the kidney due to urine backup from obstruction.

Hyperalgesia

An exaggerated pain sensation.

Hypercalcemia

Excessive calcium in the blood.

Hypercalciuria

Excessive calcium in the urine.

Hypercapnia

Elevated carbon dioxide levels in the bloodstream.

Hypercoagulable state

A disorder characterized by excessive thrombus formation.

Hyperemesis gravidarum

Severe nausea and vomiting during pregnancy leading to dehydration.

Hyperglycemic hyperosmolar nonketotic syndrome

Severe increase in serum glucose without ketone production.

Hyperopia

Farsightedness.

Hyperpigmentation

Darkening of the skin due to excess melanin deposits.

Hypertrichosis

Excessive hair growth.

Hyphae

A long, branching filamentous form of a fungus.

Hypocretin

A wake-promoting neuropeptide linked to narcolepsy.

Hypogammaglobulinemia

Reduced antibody levels.

Hypogonadism

Abnormally decreased functional activity of the gonads, affecting growth and development.

Hypomimia

Lack of facial expression; often termed masked face.

Hypophonia

Decreased volume of voice.

Hypopituitarism

Deficiency in pituitary hormone production.

Hypoxemia

Oxygen deficiency in the blood.

Hypoxia

Oxygen deficiency in body tissues.

Hysterectomy

An operation to remove a woman's uterus.