1500+ medical terms, defined.

Monoclonal antibodies (mAbs) are laboratory-produced antibodies derived from a single B-cell clone, engineered to bind one specific epitope with high specificity. They are widely used therapeutically (e.g., cancer, autoimmune disease, in...

Monoclonal antibodies (mAbs) are laboratory-produced antibodies derived from a single B-cell clone, engineered to bind a specific epitope on a target antigen with high specificity. They are widely used therapeutically (e.g., cancer, auto...

Gastric ulcers are mucosal defects extending through the muscularis mucosae into the submucosa, occurring in the stomach, most commonly at the lesser curvature of the antrum. Major causes are H. pylori infection and NSAID use, which disr...

The lower esophageal sphincter (LES) is a physiologic sphincter at the gastroesophageal junction that prevents reflux of gastric contents into the esophagus. It relaxes during swallowing to allow food passage into the stomach and remains...

The vulva refers to the external female genitalia, including the mons pubis, labia majora, labia minora, clitoris, vestibule, and vaginal/urethral openings. It serves protective and sexual function roles and is a common site for dermatol...

The lamina propria is a thin layer of loose connective tissue found beneath the epithelium of mucous membranes (mucosa), together with which it forms the mucosa lining hollow organs. It contains blood vessels, lymphatics, glands, and imm...

The renal arteries are paired vessels arising from the abdominal aorta (typically at L1-L2) that supply oxygenated blood to the kidneys. The right renal artery is longer and passes posterior to the IVC, while the left is shorter. Renal a...

The carnitine shuttle is the transport system that moves long-chain fatty acids (as acyl-CoA) across the inner mitochondrial membrane so they can undergo β-oxidation. It requires carnitine palmitoyltransferase I (CPT-I, outer membrane) a...

The obturator sign is a physical exam maneuver that elicits hypogastric or right lower quadrant pain when the hip is flexed and internally rotated, indicating irritation of the obturator internus muscle. It is classically associated with...

The psoas sign is a clinical maneuver used to assess for retroperitoneal inflammation, classically associated with acute appendicitis, particularly when the appendix is retrocecal. Pain elicited on passive extension of the hip or active...

Turcot syndrome is a rare autosomal recessive/dominant condition characterized by colonic polyposis (either FAP-type adenomas or Lynch syndrome-type) combined with primary central nervous system tumors, classically medulloblastoma or gli...

Cyclins are regulatory proteins that bind and activate cyclin-dependent kinases (CDKs) to drive progression through the cell cycle. Their levels oscillate periodically, rising and falling at specific phases to control checkpoints (G1/S,...

Proximal (Type 2) renal tubular acidosis is caused by impaired bicarbonate reabsorption in the proximal convoluted tubule, leading to a normal anion gap metabolic acidosis with a tendency toward hypokalemia. It is often part of Fanconi s...

Central venous pressure (CVP) is the pressure within the intrathoracic vena cava near the right atrium, reflecting right ventricular preload and right atrial filling pressure. Normal CVP is approximately 2-8 mmHg (or 5-12 cmH2O). It is u...

Leptin is a satiety hormone secreted by adipocytes in proportion to fat mass, acting on the hypothalamus (arcuate nucleus) to suppress appetite and increase energy expenditure. Leptin levels correlate directly with body fat stores; obesi...

Inhibin B is a glycoprotein hormone produced by Sertoli cells (males) and granulosa cells (females) that provides negative feedback on FSH secretion from the anterior pituitary. It is composed of alpha and beta subunits and serves as a m...

The duct of Wirsung is the main pancreatic duct, running the length of the pancreas from tail to head, typically joining the common bile duct to form the hepatopancreatic ampulla (ampulla of Vater), which drains into the duodenum at the...

Complex I (NADH:ubiquinone oxidoreductase) is the first and largest enzyme complex of the mitochondrial electron transport chain (ETC), oxidizing NADH and transferring electrons to ubiquinone (coenzyme Q) while pumping protons across the...

Gangrenous necrosis is a type of tissue death resulting from severe ischemia, typically affecting the extremities or GI tract, and is classified as dry (coagulative necrosis pattern) or wet (coagulative plus liquefactive necrosis due to...

VDJ recombination is the process by which B and T lymphocytes generate diverse antigen receptor genes (immunoglobulins and T-cell receptors) by randomly joining Variable, Diversity, and Joining gene segments. It is mediated by RAG1/RAG2...

Ligases are enzymes that catalyze the joining of two molecules, typically using ATP hydrolysis to form a new covalent bond. In molecular biology, DNA ligase is essential for sealing nicks in the DNA backbone during replication, repair, a...

Conjugated (direct) bilirubin is water-soluble bilirubin that has been conjugated with glucuronic acid by hepatic UDP-glucuronosyltransferase (UGT1A1). Elevated levels indicate impaired bile flow (cholestasis) or hepatocyte excretion def...

A gastric ulcer is a break in the mucosal lining of the stomach extending through the muscularis mucosa, most commonly caused by H. pylori infection or NSAID use. Pain classically worsens with eating (unlike duodenal ulcers, which improv...

Atenolol is a beta-1 selective (cardioselective) adrenergic receptor antagonist used primarily in hypertension and angina management. It has lower lipid solubility than propranolol, resulting in fewer CNS side effects and renal (not hepa...

Metoprolol is a cardioselective beta-1 adrenergic receptor antagonist (beta-blocker) used to treat hypertension, angina, heart failure, and arrhythmias. It reduces heart rate, myocardial contractility, and cardiac output by blocking symp...

Pyridoxine (vitamin B6) is a water-soluble vitamin that serves as a cofactor (as pyridoxal phosphate, PLP) for transamination, decarboxylation, and heme synthesis reactions. It is clinically important for preventing peripheral neuropathy...

Desmin is a type III intermediate filament protein found in muscle cells (skeletal, cardiac, and smooth muscle), where it forms the cytoskeletal scaffolding that connects myofibrils to the sarcolemma and nuclear membrane. Immunohistochem...

Alteplase is a recombinant tissue plasminogen activator (tPA) that converts plasminogen to plasmin, promoting fibrinolysis and clot breakdown. It is used in acute ischemic stroke, ST-elevation MI, massive pulmonary embolism, and to clear...

Tenecteplase (TNK) is a third-generation recombinant tissue plasminogen activator (tPA) used as a fibrinolytic agent for acute ST-elevation myocardial infarction (STEMI) and increasingly for acute ischemic stroke. It has greater fibrin s...

The round ligament of the uterus is a fibromuscular cord that extends from the uterine horns, through the inguinal canal, to the labia majora, helping maintain anteverted uterine position. It is the embryologic remnant of the gubernaculu...

Viral encephalitis is inflammation of the brain parenchyma caused by direct viral invasion, most commonly HSV-1 in adults/older children. Presents with fever, headache, altered mental status, seizures, and focal neurologic deficits. HSV...

Viral meningitis, also called aseptic meningitis, is inflammation of the meninges most commonly caused by enteroviruses (e.g., Coxsackievirus, Echovirus), presenting with fever, headache, photophobia, and nuchal rigidity. It typically ha...

The temporal lobe is one of the four major lobes of the cerebral cortex, located inferior to the lateral (Sylvian) fissure. It is critical for auditory processing, language comprehension (Wernicke's area), memory formation (via the hippo...

Tropomyosin is a rod-shaped regulatory protein that lies along the actin filament in both skeletal/cardiac and smooth muscle, controlling the interaction between actin and myosin during contraction. In striated muscle, it works with trop...

Alkylating agents are chemotherapeutic drugs that add alkyl groups to DNA (primarily at the N7 of guanine), causing DNA crosslinking, strand breaks, and mispairing, ultimately triggering apoptosis in rapidly dividing cells. They are cell...

Nonbacterial thrombotic endocarditis (NBTE), also called marantic endocarditis, is characterized by sterile fibrin-platelet vegetations that form on cardiac valve leaflets, typically in the setting of malignancy (especially mucinous aden...

The thyroglossal duct is an embryologic structure formed by the descent of the thyroid gland from the foramen cecum at the base of the tongue to its final position in the anterior neck. Failure of this duct to involute results in thyrogl...

The putamen is a large, rounded nucleus of the basal ganglia, located lateral to the globus pallidus and forming, together with the caudate nucleus, the striatum. It plays a key role in motor control, particularly regulation of movement...

The LDL receptor (LDLR) is a cell-surface glycoprotein that binds and internalizes LDL particles via receptor-mediated endocytosis, allowing cells to take up cholesterol and regulate plasma LDL-cholesterol levels. Loss-of-function mutati...

Sarcoma is a malignant tumor arising from mesenchymal (connective) tissue, including bone, cartilage, fat, muscle, blood vessels, and other soft tissues. Unlike carcinomas (epithelial origin), sarcomas often spread hematogenously rather...

Hematopoiesis is the process of producing all blood cell lineages (erythrocytes, leukocytes, platelets) from hematopoietic stem cells (HSCs). It occurs in the bone marrow after birth, but shifts location during fetal development (yolk sa...

Deep vein thrombosis (DVT) is the formation of a blood clot within a deep vein, most commonly in the lower extremities (femoral, popliteal, or iliac veins). It classically presents with unilateral leg swelling, warmth, erythema, and pain...

Finasteride is a 5-alpha-reductase inhibitor that blocks conversion of testosterone to dihydrotestosterone (DHT), used to treat benign prostatic hyperplasia (BPH) and male pattern baldness (androgenetic alopecia). It reduces prostate siz...

The pressure-volume (PV) loop is a graphical representation of the relationship between left ventricular pressure and volume during a single cardiac cycle. It illustrates the four phases of the cardiac cycle: isovolumetric contraction, e...

The umbilical cord is a flexible, tube-like structure connecting the fetus to the placenta, containing two umbilical arteries and one umbilical vein surrounded by Wharton's jelly. It facilitates exchange of oxygen, nutrients, and waste b...

Macrophages are large phagocytic cells of the innate immune system derived from monocytes, present in tissues throughout the body. They phagocytose pathogens, dead cells, and debris, and serve as antigen-presenting cells (APCs) that brid...

Riboflavin (Vitamin B2) is a water-soluble vitamin that serves as a precursor for the coenzymes FAD and FMN, essential for redox reactions in energy metabolism. Deficiency classically presents with angular stomatitis, cheilosis, glossiti...

Trousseau syndrome refers to migratory superficial thrombophlebitis (recurrent, spontaneous venous thromboses in different sites) associated with occult visceral malignancy, classically pancreatic adenocarcinoma. It results from cancer-i...

Infliximab is a chimeric monoclonal antibody that binds and neutralizes TNF-alpha, used to treat autoimmune inflammatory diseases such as Crohn's disease, ulcerative colitis, rheumatoid arthritis, ankylosing spondylitis, and psoriasis/ps...

Alirocumab is a monoclonal antibody that inhibits PCSK9 (proprotein convertase subtilisin/kexin type 9), leading to increased LDL receptor recycling and significantly lower LDL cholesterol levels. It is used as adjunct therapy for hyperc...