PMC Medicine Licensure key terms

The proportion of people who truly have a disease and are correctly identified as positive by a test. It reflects how well a test detects disease when it is present.

The proportion of people without a disease who are correctly identified as negative by a test. It reflects how well a test excludes disease in healthy individuals.

The probability that a person with a positive test result actually has the disease. It depends on both test accuracy and the prevalence of the condition in the population tested.

The number of new cases of a disease arising in a defined population over a specified period. It measures the rate at which new disease events occur.

The total number of existing cases of a disease in a population at a given point or period, expressed as a proportion. It reflects disease burden rather than rate of occurrence.

The proportion of a defined population that develops illness during a limited outbreak or exposure period. It is used to characterize explosive epidemics such as food-borne illness.

Indirect protection of susceptible individuals that arises when a sufficient proportion of a population is immune to an infection, reducing transmission chains and outbreak risk.

The proportion of people diagnosed with a disease who die from it within a specified period. It expresses severity of disease among those affected.

A measure of association comparing the odds of exposure among cases with the odds of exposure among controls. It approximates relative risk for rare diseases in case-control studies.

The ratio of disease incidence in an exposed group to incidence in an unexposed group. A value above one indicates increased risk associated with the exposure.

The study of how the body handles a drug over time, encompassing absorption, distribution, metabolism, and excretion. These processes determine drug concentration at target sites.

The fraction of an administered drug dose that reaches systemic circulation unchanged. Intravenous administration is defined as complete bioavailability, while oral routes are usually lower.

Breakdown of an orally administered drug in the gut wall or liver before it reaches systemic circulation. It reduces oral bioavailability and may necessitate higher oral doses.

The time required for the plasma concentration of a drug to fall by half. It guides dosing intervals and the time needed to reach steady state.

A theoretical volume relating the amount of drug in the body to its plasma concentration. Large values suggest extensive tissue distribution rather than confinement to plasma.

The ratio of the dose producing toxicity to the dose producing therapeutic effect. A narrow index means small dose changes can cause harm, requiring monitoring.

Programmed cell death involving orderly cellular breakdown without inflammation. It is essential for normal tissue turnover and removes genetically damaged cells.

Pathological cell death caused by injury, characterized by swelling, membrane rupture, and inflammation in surrounding tissue. It differs from programmed cell death.

Reversible replacement of one mature cell type by another, often in response to chronic irritation. It is an adaptive change but may predispose to malignancy.

Disordered growth in which cells show abnormal size, shape, and organization. It is not cancer but may progress to malignancy, especially in epithelial tissues.

Malignant change confined to the epithelium without invasion through the basement membrane. It has not yet acquired the ability to metastasize.

Spread of malignant cells from a primary tumor to distant sites through lymphatics, blood, or body cavities, forming secondary deposits. It is a defining feature of malignancy.

Death of tissue due to interruption of its blood supply, usually from arterial occlusion. The resulting lesion is an infarct, commonly seen in heart, brain, and bowel.

Formation of a blood clot within a vessel or heart chamber during life. It may obstruct flow locally or embolize to distant vessels.

Occlusion of a blood vessel by material traveling through the circulation, such as a clot, fat, air, or amniotic fluid. It often originates from a proximal thrombus.

A differential staining method that divides bacteria into gram-positive and gram-negative groups based on cell wall structure. It guides early empirical antibiotic choice.

Laboratory technique in which a specimen is incubated to grow organisms and then tested against antibiotics to determine susceptibility. It confirms infection and guides targeted therapy.

The lowest concentration of an antimicrobial that prevents visible growth of a microorganism in vitro. It quantifies susceptibility and informs dosing decisions.

Bacteria that retain stain after treatment with acid-alcohol, notably mycobacteria. Their waxy cell walls require special staining such as Ziehl-Neelsen.

Postmortem stiffening of muscles caused by depletion of ATP and persistent actin-myosin cross-bridging. It develops over hours and later resolves as tissue decomposes.

Postmortem purplish discoloration of dependent skin caused by gravitational settling of blood after circulation stops. Its distribution helps assess body position after death.

The gradual cooling of a body after death until it approaches ambient temperature. The rate of cooling is used to estimate time since death.

A scored assessment of consciousness based on eye opening, verbal response, and motor response. Scores range from three to fifteen and guide severity classification of head injury.

Elevation of pressure within the rigid skull from causes such as hemorrhage, edema, or tumor. It risks brain herniation and requires urgent recognition and treatment.

The combination of hypertension with widened pulse pressure, bradycardia, and irregular respiration seen in severe raised intracranial pressure. It signals impending brain herniation.

A pregnancy disorder marked by new hypertension and proteinuria or other organ dysfunction after twenty weeks of gestation. It threatens both mother and fetus and may progress to seizures.

The occurrence of generalized seizures in a woman with preeclampsia, without another identifiable cause. It is an obstetric emergency requiring prompt magnesium therapy and delivery.

A severe pregnancy complication characterized by hemolysis, elevated liver enzymes, and low platelets. It often accompanies preeclampsia and requires urgent obstetric management.

Excessive bleeding after childbirth, commonly defined as blood loss over 500 mL after vaginal delivery or 1000 mL after cesarean. Uterine atony is the most frequent cause.

Yellow discoloration of skin and eyes in a newborn due to elevated bilirubin. It is common and usually benign but can cause brain injury if severe and untreated.

Permanent neurological damage from deposition of unconjugated bilirubin in the basal ganglia of a newborn. It is prevented by timely detection and treatment of severe jaundice.

A kidney disorder marked by heavy proteinuria, low blood albumin, edema, and high cholesterol. It results from increased glomerular permeability and predisposes to infection and clotting.

The volume of plasma filtered by the kidneys per unit time, used to assess renal function. It falls in chronic kidney disease and guides drug dosing.

A metabolic emergency of insulin deficiency causing high blood glucose, ketone accumulation, and metabolic acidosis. It requires fluid replacement, insulin, and correction of electrolyte disturbances.

A rapid change in membrane potential that travels along excitable cells such as neurons and muscle fibers. It depends on ion channel activity and underlies nerve and muscle signaling.

The steady electrical voltage across a cell membrane at rest, typically negative inside. It is set mainly by potassium permeability and the sodium-potassium pump.

Fast propagation of action potentials by jumping between nodes of Ranvier along myelinated axons. It increases conduction velocity compared with unmyelinated fibers.

The principle that increased stretching of cardiac muscle, within limits, strengthens contraction and raises stroke volume. It links venous return to cardiac output.

The volume of blood pumped by the heart per minute, equal to heart rate multiplied by stroke volume. It is a key determinant of tissue oxygen delivery.

The cytoplasmic pathway that converts glucose to pyruvate with net production of ATP and NADH. It functions with or without oxygen and is central to cellular energy metabolism.

A mitochondrial cycle that oxidizes acetyl-CoA to carbon dioxide while generating NADH, FADH2, and GTP. It feeds electrons into the respiratory chain for ATP production.

Mitochondrial production of ATP driven by an electrochemical proton gradient across the inner membrane. It is the main energy source in aerobic cells.

Synthesis of glucose from non-carbohydrate precursors such as lactate, glycerol, and amino acids, mainly in liver and kidney. It maintains blood glucose during fasting.

A network of spinal nerves from C5 to T1 that supplies the upper limb. Its roots, trunks, divisions, cords, and branches are commonly tested in limb anatomy.

A major nerve of the upper limb that supplies most forearm flexors and thenar muscles and provides sensation to the lateral palm and fingers. It passes through the carpal tunnel.

Compression of the median nerve as it passes beneath the flexor retinaculum at the wrist. It causes pain, numbness, and weakness in the median nerve distribution.

A branch of the posterior cord of the brachial plexus that supplies the deltoid and teres minor and the skin over the shoulder. It is at risk in shoulder dislocation.

A triangular region of the anterior thigh bounded by the inguinal ligament, sartorius, and adductor longus. It contains the femoral nerve, artery, and vein and is a site for vascular access.

An oblique passage through the lower abdominal wall containing the spermatic cord in males and the round ligament in females. It is a common site of hernia formation.