Medical Terminology and Basic Sciences
Building and decoding terms
Medical language is assembled from a root (organ or tissue), a prefix (location, number, direction), and a suffix (condition, procedure, or test). Learn combining forms in families: hepat/o liver, nephr/o kidney, cyt/o cell, cyst/o bladder or sac, lith/o stone, lip/o fat. Prefixes carry direction or quantity: hyper- above or excess, hypo- below or deficient, dys- difficult or abnormal. Suffixes name the finding: -itis inflammation, -megaly enlargement, -emia blood condition, -uria urine condition.
Basic-science anchors
pH is −log[H+]; a buffer resists change near its pKa, as described by Henderson–Hasselbalch: pH = pKa + log([A−]/[HA]). Calculated serum osmolality ≈ 2[Na+] + glucose/18 + BUN/2.8 when values are in mg/dL. Anion gap = Na+ − (Cl− + HCO3−), normally about 8–12 mmol/L; it rises with unmeasured anions such as lactate or ketones. The Beer–Lambert law (A = εbc) explains why absorbance is proportional to concentration in spectrophotometric assays when path length and molar absorptivity are constant.
Worked example
A note reads “nephrolithiasis with hematuria.” Decode: nephr/o (kidney) + lith/o (stone) + -iasis (condition) = kidney stones; hemat/o (blood) + -uria (urine) = blood in urine. If the same patient has Na 132, Cl 96, and HCO3 12 mmol/L, the anion gap is 132 − (96 + 12) = 24 mmol/L. The elevated gap fits a metabolic acidosis from ketones or lactate, so the terminology and the calculation support the same clinical picture.
Traps
Do not confuse -emia (blood) with -uria (urine), hyper- with hypo-, or cyt/o with cyst/o. Abbreviations are context-dependent: PT can mean prothrombin time or physical therapy; MS can mean mitral stenosis, multiple sclerosis, or mass spectrometry. Conventional and SI units differ (glucose mg/dL vs mmol/L; creatinine mg/dL vs µmol/L), so check the unit before comparing a result with a reference interval.