MECEE-PG Nepal key terms

The body's active maintenance of stable internal conditions such as temperature, pH, and blood glucose around a set point, achieved through negative feedback loops involving sensors, control centres, and effectors.

A control mechanism in which a change in a regulated variable triggers a response that opposes that change, restoring the variable toward its normal range; the dominant regulatory principle in physiology.

A rapid, all-or-none reversal of membrane potential along an excitable cell, produced by sequential opening of voltage-gated sodium then potassium channels, used to transmit signals along neurons and muscle fibres.

The steady electrical voltage across a cell membrane at rest, typically about minus seventy millivolts in neurons, set mainly by potassium permeability and the sodium-potassium pump.

Fast, jumping propagation of an action potential between nodes of Ranvier along a myelinated axon, which increases conduction velocity and reduces energy cost compared with unmyelinated fibres.

The volume of plasma filtered by the renal glomeruli per unit time, normally about 125 mL per minute in adults; a key index of kidney function estimated from creatinine or cystatin C.

The volume of plasma completely cleared of a substance per unit time, calculated as urine concentration times urine flow divided by plasma concentration; used to measure renal function and renal plasma flow.

The total concentration of dissolved solute particles per kilogram of solvent, determining water movement across membranes and guiding fluid and electrolyte therapy.

The component of osmotic pressure exerted by plasma proteins, chiefly albumin, that draws water into the vascular compartment and helps maintain circulating blood volume.

The quantitative description of enzyme-catalysed reaction rates, where the Michaelis constant Km reflects substrate affinity and maximum velocity Vmax reflects enzyme amount at saturation.

Reversible enzyme inhibition in which an inhibitor resembling the substrate binds the active site, raising apparent Km without changing Vmax; overcome by increasing substrate concentration.

A non-protein molecule or ion, such as a metal ion or coenzyme, required by an enzyme for catalytic activity and often transiently bound during the reaction.

The cytosolic pathway that converts one glucose molecule into two pyruvate molecules, generating net two ATP and two NADH, and functioning with or without oxygen.

The synthesis of glucose from non-carbohydrate precursors such as lactate, glycerol, and amino acids, occurring mainly in liver and kidney and important during fasting.

Formation of ketone bodies (acetoacetate, beta-hydroxybutyrate, acetone) from acetyl-CoA in liver mitochondria during prolonged fasting or uncontrolled diabetes, providing alternative fuel for tissues.

Irreversible cell injury leading to uncontrolled cell death, with membrane rupture, enzyme leakage, and surrounding inflammation; distinct from programmed apoptosis.

Programmed, energy-dependent cell death with cell shrinkage, chromatin condensation, and membrane-bound bodies cleared without inflammation; important in development and tumour surveillance.

Reversible change in which one mature differentiated cell type is replaced by another, often squamous epithelium replacing columnar epithelium in response to chronic irritation such as smoking.

Disordered growth with loss of uniformity and architectural orientation of cells, showing nuclear atypia and increased mitoses; a pre-malignant change but not yet invasive cancer.

Classification of cancer extent by primary tumour size, nodal involvement, and distant metastasis (TNM), which guides prognosis and treatment choice more strongly than histological grade.

The ratio of a drug dose producing toxicity to the dose producing the desired effect; a narrow index means small dose changes can cause harm and demands careful monitoring.

Presystemic breakdown of an orally administered drug in gut wall or liver before it reaches systemic circulation, reducing oral bioavailability and favouring alternative routes when severe.

The fraction of an administered drug dose that reaches systemic circulation unchanged; one hundred percent for intravenous dosing and usually lower for oral dosing.

The time taken for plasma drug concentration to fall by half, determined by volume of distribution and clearance; guides dosing interval and time to steady state.

The lowest concentration of an antimicrobial that prevents visible growth of a microorganism under defined laboratory conditions, used to classify susceptibility and guide therapy.

The ability of a microorganism to survive and multiply despite a drug concentration that would normally inhibit or kill it, arising through enzymatic inactivation, target alteration, or reduced accumulation.

The complete destruction or removal of all microorganisms, including bacterial spores, from an object or medium, commonly by autoclaving, dry heat, or filtration.

Immediate immunoglobulin E-mediated allergic reaction in which mast cell degranulation releases histamine, producing urticaria, bronchospasm, or anaphylaxis within minutes of exposure.

Reduced responsiveness of tissues, especially muscle, fat, and liver, to insulin action, leading to compensatory hyperinsulinaemia and eventually type 2 diabetes mellitus.

A clinical complex of heavy proteinuria, hypoalbuminaemia, oedema, and hyperlipidaemia caused by glomerular disease, with oedema driven largely by low plasma oncotic pressure.

Acute circulatory failure with inadequate tissue perfusion and oxygen delivery, causing cellular dysfunction and organ injury; classified as hypovolaemic, cardiogenic, distributive, or obstructive.

Presence of air in the pleural space causing lung collapse; a tension pneumothorax progressively raises intrathoracic pressure and obstructs venous return, requiring immediate needle decompression.

Pregnancy-specific disorder after twenty weeks of gestation characterised by new hypertension with proteinuria or other organ dysfunction, threatening mother and fetus if untreated.

Glucose intolerance first recognised during pregnancy, reflecting pregnancy-induced insulin resistance; increases risks of macrosomia, birth trauma, and later maternal type 2 diabetes.

Feeding an infant only breast milk, without water or other liquids or solids, for the first six months of life, followed by continued breastfeeding with complementary foods.

A plotted reference of weight, length, or head circumference against age used to detect faltering growth, undernutrition, or obesity in children during routine monitoring.

Treatment of dehydration using a balanced glucose-electrolyte solution; glucose-coupled sodium absorption drives water uptake, making it life-saving in diarrhoeal disease.

Indirect protection of unvaccinated individuals that arises when a sufficiently high proportion of a population is immune, interrupting chains of transmission.

Sensitivity is the proportion of truly diseased people correctly identified by a test; specificity is the proportion of truly healthy people correctly identified as negative.

The probability that a person with a positive test result actually has the disease; it rises with disease prevalence, unlike sensitivity and specificity.

Incidence is the number of new cases arising in a population over a period; prevalence is the total existing cases at a point or period, reflecting both incidence and disease duration.