--- title: "Health & Medical Glossary A to Z | infoMD" description: "Plain-English explanations of medical terms, conditions, and concepts. Browse our comprehensive health glossary to understand medical terminology." lang: en json-ld: | [ { "@context": "https://schema.org", "@type": "DefinedTermSet", "name": "infoMD Health & Medical Glossary", "description": "Plain-English explanations of medical terms, conditions, and concepts.", "url": "https://infomd.com/glossary" }, { "@context": "https://schema.org", "@type": "BreadcrumbList", "itemListElement": [ { "@type": "ListItem", "position": 1, "name": "Home", "item": "https://infomd.com" }, { "@type": "ListItem", "position": 2, "name": "Glossary", "item": "https://infomd.com/glossary" } ] } ] --- [Skip to main content](#main-content) [![infoMD](/assets/infomd-logo-CtvTblFD.png)](/) [Home](/) [Conditions](/conditions) [Glossary](/glossary)[Shop](/shop) # Health & Medical Glossary Plain-English explanations of medical terms, conditions, and concepts [A](#letter-A)[B](#letter-B)[C](#letter-C)[D](#letter-D)[E](#letter-E)[F](#letter-F)[G](#letter-G)[H](#letter-H)[I](#letter-I)[J](#letter-J)[K](#letter-K)[L](#letter-L)[M](#letter-M)[N](#letter-N)[O](#letter-O)[P](#letter-P)[Q](#letter-Q)[R](#letter-R)[S](#letter-S)[T](#letter-T)[U](#letter-U)[V](#letter-V)[W](#letter-W)[X](#letter-X)[Y](#letter-Y)[Z](#letter-Z) 1. [Home](/) 2. Glossary ## A [Acne Vulgaris](/glossary/acne-vulgaris) - Acne vulgaris is the medical name for ordinary acne - the most common skin condition in the world, affecting an estimate... [Adrenal Fatigue](/glossary/adrenal-fatigue) - Adrenal fatigue is a term used in alternative and integrative medicine to describe a collection of symptoms - including ... [AHA (Alpha Hydroxy Acid)](/glossary/aha-alpha-hydroxy-acid) - Alpha hydroxy acids, or AHAs, are a family of water-soluble exfoliating acids derived from natural sources. The most com... [Allergen](/glossary/allergen) - An allergen is any substance that triggers an abnormal immune response in a person who is sensitized to it, even though ... Used in 1 article [Alopecia Areata](/glossary/alopecia-areata) - Alopecia areata is an autoimmune condition in which the immune system mistakenly attacks the body's own hair follicles, ... [Amino Acid](/glossary/amino-acid) - Amino acids are organic molecules that serve as the fundamental building blocks of proteins in your body. There are 20 s... Used in 2 articles [Anagen Phase](/glossary/anagen-phase) - Anagen is the active growth phase of the hair cycle. During anagen, cells in the hair bulb divide rapidly and push the h... [Androgenic Alopecia](/glossary/androgenic-alopecia) - Androgenic alopecia is the most common form of hair loss in both men and women. It is driven by a combination of genetic... [Anemia](/glossary/anemia) - Anemia is a condition in which your blood doesn't have enough healthy red blood cells or hemoglobin to carry adequate ox... Used in 2 articles [Anti-inflammatory](/glossary/anti-inflammatory) - Anti-inflammatory refers to any substance or treatment that reduces inflammation - the body's natural immune response to... ⭐ Used in 6 articles [Antibody](/glossary/antibody) - An antibody is a Y-shaped protein produced by specialized white blood cells called B lymphocytes (B cells) as part of th... [Antigen](/glossary/antigen) - An antigen is any molecule or molecular structure that can be recognized by the immune system and trigger an immune resp... [Aorta](/glossary/aorta) - The aorta is the largest artery in the human body, originating from the left ventricle of the heart and extending down t... [Arrhythmia](/glossary/arrhythmia) - An arrhythmia is any abnormality in the timing or pattern of your heartbeat. Your heart normally beats in a regular, coo... Used in 2 articles [Atherosclerosis](/glossary/atherosclerosis) - Atherosclerosis is a condition where fatty deposits called plaques build up inside the walls of your arteries - the bloo... Used in 1 article [Autoimmune Response](/glossary/autoimmune-response) - An autoimmune response occurs when the immune system mistakenly identifies the body's own healthy cells and tissues as f... [Azelaic Acid](/glossary/azelaic-acid) - Azelaic acid is a dicarboxylic acid that is naturally produced by yeast on the skin and is also synthesized for medical ... ## B [Benzoyl Peroxide](/glossary/benzoyl-peroxide) - Benzoyl peroxide is an antimicrobial ingredient used for decades as a first-line treatment for inflammatory acne. When a... Used in 1 article [BHA (Beta Hydroxy Acid)](/glossary/bha-beta-hydroxy-acid) - Beta hydroxy acid - in cosmetic skincare almost always salicylic acid - is an oil-soluble exfoliating acid. That oil-sol... [Biomarker](/glossary/biomarker) - A biomarker (short for biological marker) is a measurable indicator of a biological state or condition. Biomarkers can b... [Biotin](/glossary/biotin) - Biotin is a B vitamin (B7) that helps the body convert food into energy and is involved in the synthesis of keratin and ... [Blood Glucose](/glossary/blood-glucose) - Blood glucose refers to the concentration of glucose (a simple sugar) circulating in your bloodstream. Glucose is your b... ⭐ Used in 3 articles [Blood Pressure](/glossary/blood-pressure) - Blood pressure is the force exerted by circulating blood against the walls of your arteries as the heart pumps it throug... ⭐ Used in 10 articles [Blood-Brain Barrier](/glossary/blood-brain-barrier) - The blood-brain barrier (BBB) is a highly selective semi-permeable border of specialized cells that separates the circul... Used in 2 articles [Blue Light Therapy (skincare)](/glossary/blue-light-therapy-skincare) - Blue light therapy in skincare uses visible blue light - typically in the 415nm range - to target Cutibacterium acnes, t... [BMI](/glossary/bmi) - BMI (Body Mass Index) is a numerical value calculated from a person's weight and height that is used as a screening tool... [Brain Fog](/glossary/brain-fog) - Brain fog is a term used to describe a cluster of cognitive symptoms including difficulty concentrating, forgetfulness, ... Used in 1 article [Broad Spectrum UV Protection](/glossary/broad-spectrum-uv-protection) - 'Broad spectrum' on a sunscreen label means the product has passed FDA testing for both UVA and UVB protection. This mat... [Bronchodilator](/glossary/bronchodilator) - A bronchodilator is a type of medication that relaxes and widens (dilates) the airways (bronchi and bronchioles) in the ... Used in 1 article ## C [Cardiovascular](/glossary/cardiovascular) - Cardiovascular refers to anything related to the heart (cardio) and blood vessels (vascular) - the circulatory system th... ⭐ Used in 14 articles [Catagen Phase](/glossary/catagen-phase) - Catagen is the short transitional phase of the hair cycle that follows the growth phase (anagen). During catagen the hai... [Ceramides](/glossary/ceramides) - Ceramides are a family of fatty molecules (lipids) that make up roughly half of the lipid 'mortar' that holds the cells ... Used in 1 article [Chemical Peel](/glossary/chemical-peel) - A chemical peel is an in-office (or, at lower strengths, at-home) treatment in which an acid solution is applied to the ... [Cholesterol](/glossary/cholesterol) - Cholesterol is a waxy, fat-like substance found in every cell of your body. Despite its bad reputation, cholesterol is e... ⭐ Used in 4 articles [Chronic Inflammation](/glossary/chronic-inflammation) - Chronic inflammation is a prolonged, low-level inflammatory response that persists for weeks, months, or even years - un... Used in 1 article [Circadian Rhythm](/glossary/circadian-rhythm) - A circadian rhythm is a roughly 24-hour internal biological cycle that regulates many of your body's processes, includin... Used in 2 articles [Cognitive Behavioral Therapy](/glossary/cognitive-behavioral-therapy) - Cognitive behavioral therapy (CBT) is a structured, evidence-based form of psychotherapy that focuses on identifying and... ⭐ Used in 4 articles [Collagen](/glossary/collagen) - Collagen is the most abundant protein in the human body, making up approximately 30% of all protein and serving as the p... Used in 1 article [Comedone](/glossary/comedone) - A comedone is a plugged hair follicle and the building block of acne. It forms when dead skin cells, sebum, and sometime... [Cortisol](/glossary/cortisol) - Cortisol is a steroid hormone produced by the adrenal glands (small glands sitting atop each kidney) that plays a centra... ⭐ Used in 10 articles [Cytokines](/glossary/cytokines) - Cytokines are small proteins released by cells that act as chemical messengers of the immune system. They play a crucial... ⭐ Used in 4 articles ## D [Dermal Papilla](/glossary/dermal-papilla) - The dermal papilla is a small cluster of specialized cells at the base of every hair follicle. It is the command center ... [Dermis](/glossary/dermis) - The dermis is the thick middle layer of your skin, sitting between the epidermis on top and the subcutaneous fat below. ... Used in 1 article [Detoxification](/glossary/detoxification) - Detoxification is the physiological process by which your body identifies, neutralizes, and eliminates harmful substance... [DHEA](/glossary/dhea) - DHEA (dehydroepiandrosterone) is a hormone produced primarily by the adrenal glands that serves as a precursor - a build... [DHT (Dihydrotestosterone)](/glossary/dht-dihydrotestosterone) - Dihydrotestosterone (DHT) is an androgen hormone produced when the enzyme 5-alpha reductase converts testosterone into a... [DHT-Blocking Foods](/glossary/dht-blocking-foods) - A handful of foods contain compounds that weakly inhibit 5-alpha reductase, the enzyme that converts testosterone into D... [Dopamine](/glossary/dopamine) - Dopamine is a neurotransmitter - a chemical messenger that transmits signals between nerve cells in the brain and throug... ⭐ Used in 6 articles [Dutasteride](/glossary/dutasteride) - Dutasteride is a 5-alpha reductase inhibitor closely related to finasteride but more potent: it blocks both Type I and T... [Dysbiosis](/glossary/dysbiosis) - Dysbiosis refers to an imbalance in the composition or function of the microbial communities (microbiome) that live in a... Used in 1 article ## E [Ejection Fraction](/glossary/ejection-fraction) - Ejection fraction is a measurement of how well your heart pumps blood with each beat, expressed as a percentage. Specifi... [Electrolytes](/glossary/electrolytes) - Electrolytes are minerals that carry an electrical charge when dissolved in body fluids like blood, urine, and sweat. Th... [Endometriosis](/glossary/endometriosis) - Endometriosis is a chronic condition in which tissue similar to the lining of the uterus (the endometrium) grows outside... [Endorphins](/glossary/endorphins) - Endorphins are a group of neurotransmitters produced naturally by the central nervous system and pituitary gland that ac... [Enzyme](/glossary/enzyme) - An enzyme is a specialized protein that acts as a biological catalyst - it speeds up chemical reactions in the body with... Used in 2 articles [Epidermis](/glossary/epidermis) - The epidermis is the outermost layer of your skin - the part you can see and touch. It is remarkably thin (about as thic... [Epigenetics](/glossary/epigenetics) - Epigenetics is the study of changes in gene expression that occur without altering the underlying DNA sequence. While yo... [Estrogen](/glossary/estrogen) - Estrogen is a group of steroid hormones that play central roles in the development and regulation of the female reproduc... ## F [Facial Gua Sha](/glossary/facial-gua-sha) - Gua sha is a traditional Chinese medicine technique in which a smooth-edged stone tool is used to apply firm strokes to ... [Fascia](/glossary/fascia) - Fascia is a thin, tough, web-like connective tissue that wraps around and connects every muscle, bone, organ, nerve, and... Used in 1 article [Fibroblasts](/glossary/fibroblasts) - Fibroblasts are the workhorse cells of the dermis. They manufacture collagen, elastin, and hyaluronic acid - the three s... [Finasteride](/glossary/finasteride) - Finasteride is an FDA-approved oral medication for male pattern hair loss. It works by inhibiting Type II 5-alpha reduct... [Follicle Miniaturization](/glossary/follicle-miniaturization) - Follicle miniaturization is the gradual shrinking of hair follicles that drives androgenic alopecia. With each successiv... [FPHL (Female Pattern Hair Loss)](/glossary/fphl-female-pattern-hair-loss) - Female pattern hair loss is the most common form of hair loss in women, affecting up to 40% by age 50. It typically pres... [Free Radicals](/glossary/free-radicals) - Free radicals are unstable, highly reactive molecules that have one or more unpaired electrons in their outer shell. Thi... [FUE (Follicular Unit Extraction)](/glossary/fue-follicular-unit-extraction) - Follicular Unit Extraction, or FUE, is the more modern of the two main hair transplant techniques. Instead of removing a... [Functional Medicine](/glossary/functional-medicine) - Functional medicine is a patient-centered, systems-based approach to healthcare that focuses on identifying and addressi... [FUT (Follicular Unit Transplantation)](/glossary/fut-follicular-unit-transplantation) - Follicular Unit Transplantation, or FUT, is the older of the two main hair transplant techniques. In FUT, a strip of sca... 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