PMC Medicine Licensure cheat sheet

Acute MI: ST-elevation in two contiguous leads; troponin rises 3-6 h after onset and peaks at 12-24 h.

DKA: anion-gap metabolic acidosis with glucose >250 mg/dL, ketones, and serum bicarbonate <18 mEq/L; total body potassium is depleted despite normal serum K.

Nephrotic syndrome: proteinuria >3.5 g/day, hypoalbuminemia, edema, hyperlipidemia; minimal change disease is the commonest cause in children.

Hyperthyroidism: TSH low with elevated free T4; Graves disease shows diffuse uptake and TSH-receptor antibodies.

Cirrhosis complications: portal hypertension gives ascites, varices, and splenomegaly; spontaneous bacterial peritonitis is diagnosed by ascitic neutrophil count >250/mm3.

Infective endocarditis: modified Duke criteria use persistent bacteremia and echocardiographic vegetations; viridans streptococci follow dental sources.

Anaphylaxis: intramuscular epinephrine 0.3-0.5 mg of 1:1000 solution into the anterolateral thigh is first-line therapy.

Stroke: thrombolysis window is 4.5 h from symptom onset; noncontrast CT excludes hemorrhage before treatment.

Acute appendicitis: migration of pain to the right iliac fossa with rebound tenderness at McBurney point; Alvarado score stratifies likelihood.

Small bowel obstruction: colicky pain, vomiting, distension, absolute constipation; erect abdominal film shows multiple air-fluid levels.

Acute pancreatitis: diagnosis needs two of three - characteristic pain, lipase/amylase >3 times upper limit, and imaging findings.

Burn fluid resuscitation: Parkland formula gives 4 mL/kg per percent total body surface area of Ringer lactate in 24 h, half in first 8 h.

Thyroid surgery: recurrent laryngeal nerve injury causes hoarseness; external branch of superior laryngeal nerve injury impairs high-pitch phonation.

Breast cancer: sentinel lymph node biopsy is standard for clinically node-negative axilla; estrogen receptor positivity predicts tamoxifen response.

Fracture healing: hematoma, fibrocartilaginous callus, bony callus, and remodeling; smoking and infection delay union.

Shock in trauma: class III hemorrhage (30-40% loss) produces tachycardia, hypotension, and decreased pulse pressure with normal mental status.

Estimated delivery date: Naegele rule adds 280 days to the first day of the last menstrual period.

Preeclampsia: hypertension after 20 weeks with proteinuria or end-organ dysfunction; magnesium sulfate prevents and treats eclampsia.

Postpartum hemorrhage: uterine atony is commonest cause; management sequence is uterine massage, oxytocin, then ergometrine or prostaglandins.

Ectopic pregnancy: risk factors include tubal surgery and pelvic inflammatory disease; discriminatory hCG zone with empty uterus on transvaginal scan.

Fetal heart rate monitoring: late decelerations indicate uteroplacental insufficiency; variable decelerations indicate cord compression.

Contraception: combined oral pills are contraindicated in migraine with aura, smoking over age 35, and prior venous thromboembolism.

Cervical cancer screening: HPV testing with or without cytology; HPV types 16 and 18 cause most cervical cancers.

Rhesus prophylaxis: anti-D immunoglobulin given to Rh-negative unsensitized mothers at 28 weeks and within 72 h of delivery.

Neonatal jaundice: physiologic jaundice appears after 24 h; jaundice within 24 h is always pathologic and requires investigation.

Breastfeeding: exclusive breastfeeding is recommended for the first 6 months, with complementary foods from 6 months.

Growth: birth weight doubles by 5 months and triples by 12 months; length increases about 25 cm in the first year.

Kawasaki disease: fever >5 days plus conjunctivitis, mucosal changes, rash, extremity changes, and cervical lymphadenopathy; coronary aneurysms are the main complication.

Nephrotic syndrome in children: minimal change disease responds to corticosteroids; biopsy is reserved for atypical features.

Croup: barking cough and inspiratory stridor treated with a single dose of dexamethasone; nebulized epinephrine for severe obstruction.

Intussusception: colicky pain with drawing up of legs and red-currant jelly stool; air enema is diagnostic and therapeutic.

Immunization: BCG at birth protects against disseminated tuberculosis; measles vaccine is given at 9 and 15 months in endemic settings.

Median nerve: supplies thenar muscles and lateral two lumbricals; carpal tunnel syndrome causes numbness of thumb, index, and middle fingers.

Femoral triangle: bounded by inguinal ligament, sartorius, and adductor longus; femoral nerve, artery, and vein run lateral to medial.

Brachial plexus: C5-C6 roots form upper trunk; injury causes Erb palsy with waiter-tip posture.

Portal vein: formed by superior mesenteric and splenic veins behind the neck of pancreas; drains into hepatic sinusoids.

Recurrent laryngeal nerve: left loops under aortic arch, right under right subclavian artery; both ascend in tracheoesophageal groove.

Coronary arteries: left anterior descending supplies anterior two-thirds of interventricular septum and left ventricular apex.

Inguinal canal: deep ring lateral to inferior epigastric artery; indirect hernias pass through it and are commonest in young males.

Kidney relations: left kidney lies at T12-L3, right slightly lower due to liver; ureter crosses pelvic brim at bifurcation of common iliac artery.

Cardiac output equals heart rate times stroke volume; normal resting output is about 5 L/min.

Frank-Starling law: increased end-diastolic volume raises stroke volume up to a physiologic limit.

Oxygen-hemoglobin dissociation: right shift from raised CO2, acidosis, temperature, and 2,3-BPG; left shift from fetal hemoglobin and carbon monoxide.

Glomerular filtration rate depends on net filtration pressure and filtration coefficient; autoregulation holds flow stable between 80 and 180 mmHg.

Action potential: resting membrane potential near -70 mV set mainly by potassium permeability; plateau in cardiac muscle from calcium influx.

Countercurrent mechanism: loop of Henle generates medullary hypertonicity; ADH increases collecting duct water permeability via aquaporin-2.

Respiratory control: central chemoreceptors respond to arterial PCO2 via cerebrospinal fluid pH; peripheral carotid bodies respond to hypoxia.

Gastric acid secretion: parietal cells secrete HCl stimulated by histamine, gastrin, and acetylcholine; somatostatin inhibits.

Glycolysis: net yield of 2 ATP and 2 NADH per glucose; phosphofructokinase-1 is the rate-limiting enzyme.

Krebs cycle: one acetyl-CoA yields 3 NADH, 1 FADH2, and 1 GTP; occurs in the mitochondrial matrix.

Urea cycle: converts ammonia to urea in liver; carbamoyl phosphate synthetase I is rate-limiting and activated by N-acetylglutamate.

Phenylketonuria: deficiency of phenylalanine hydroxylase causes hyperphenylalaninemia; treatment is a phenylalanine-restricted diet.

HMP shunt: generates NADPH and ribose-5-phosphate; glucose-6-phosphate dehydrogenase deficiency causes hemolysis after oxidant exposure.

Fatty acid oxidation: beta-oxidation in mitochondria yields acetyl-CoA; carnitine shuttle transports long-chain fatty acids inward.

DNA replication: semiconservative; DNA polymerase synthesizes 5-prime to 3-prime; telomerase extends chromosome ends.

Enzyme kinetics: Michaelis-Menten constant Km equals substrate concentration at half maximal velocity; low Km indicates high affinity.

Acute inflammation: neutrophils predominate in first 6-24 h; chronic inflammation features lymphocytes, plasma cells, and macrophages.

Necrosis types: coagulative from ischemia, caseous in tuberculosis, liquefactive in brain infarcts and abscesses, fat necrosis in pancreatitis.

Malignant neoplasms: invade and metastasize; grading describes differentiation, staging describes spread and predicts prognosis better.

Tumor suppressor genes: both alleles must be inactivated; retinoblastoma follows the two-hit hypothesis.

Oncogenes: gain-of-function mutations; HER2 amplification in breast cancer predicts trastuzumab response.

Granuloma: collection of epithelioid macrophages with giant cells; seen in tuberculosis, sarcoidosis, and Crohn disease.

Atherosclerosis: intimal lipid plaques with foam cells; complicated plaque rupture causes thrombosis and infarction.

Anemia classification: microcytic from iron deficiency or thalassemia; macrocytic from B12 or folate deficiency.

Beta-lactam antibiotics inhibit cell wall synthesis by binding penicillin-binding proteins; clavulanate extends spectrum by inhibiting beta-lactamase.

Aminoglycosides bind the 30S ribosomal subunit, are bactericidal, and cause nephrotoxicity and ototoxicity.

Warfarin inhibits vitamin K epoxide reductase, reducing factors II, VII, IX, and X; INR monitoring is required.

Heparin potentiates antithrombin III; protamine sulfate reverses unfractionated heparin.

ACE inhibitors reduce angiotensin II formation and cause cough and hyperkalemia; contraindicated in pregnancy.

Atropine is a competitive muscarinic antagonist causing mydriasis, dry mouth, and tachycardia.

Paracetamol overdose depletes glutathione; N-acetylcysteine replenishes it and is the antidote.

First-order kinetics: constant fraction eliminated per unit time; zero-order kinetics occurs when enzymes are saturated, as with phenytoin and ethanol.

Gram-positive cocci in clusters with coagulase positivity identify Staphylococcus aureus.

Streptococcus pyogenes is bacitracin sensitive and causes pharyngitis, impetigo, and post-streptococcal glomerulonephritis.

Mycobacterium tuberculosis is acid-fast due to mycolic acids in the cell wall; cultured on Lowenstein-Jensen medium.

Vibrio cholerae produces cholera toxin that increases cAMP, causing secretory watery diarrhea.

Hepatitis B: surface antigen indicates infection; core IgM indicates acute infection; e antigen indicates high infectivity.

Malaria: Plasmodium falciparum causes severe disease with banana-shaped gametocytes and quotidian fever.

Sterilization: autoclave at 121 degrees Celsius and 15 psi for 15 minutes kills spores; alcohol is a disinfectant not a sterilant.

Normal flora: skin predominantly coagulase-negative staphylococci; colon anaerobes outnumber aerobes by a wide margin.

Rigor mortis: begins 1-2 h after death, peaks at 12 h, and resolves by 24-36 h in temperate climates.

Livor mortis: hypostatic staining appears 2-4 h after death and becomes fixed by 8-12 h.

Drowning: diatom testing of bone marrow supports antemortem drowning.

Consent: valid consent requires capacity, adequate information, and voluntariness; minors generally require guardian consent.

Fitness to stand trial: requires understanding of charges and ability to instruct counsel; distinct from criminal responsibility.

Glasgow Coma Scale: eye, verbal, and motor scores sum to 3-15; score of 8 or less indicates severe head injury.

Defense mechanisms: projection attributes own unacceptable feelings to others; rationalization uses logical justification.

Depression: core features are low mood and anhedonia for at least 2 weeks; suicidal risk must be assessed explicitly.

Incidence measures new cases per population at risk per unit time; prevalence measures all existing cases at a point.

Sensitivity equals true positives divided by true positives plus false negatives; specificity equals true negatives divided by true negatives plus false positives.

Positive predictive value depends on disease prevalence; it falls as prevalence decreases.

Relative risk compares incidence in exposed and unexposed groups; attributable risk is the difference between them.

Herd immunity threshold depends on basic reproduction number; measles requires very high coverage due to high transmissibility.

Screening tests require high sensitivity and acceptable specificity; confirmatory tests follow positive screens.

Infant mortality rate equals infant deaths under 1 year per 1000 live births in the same year.

Case-control studies estimate odds ratios and suit rare diseases but are prone to recall bias.

Asthma: reversible airflow obstruction with FEV1/FVC ratio below 0.7; inhaled corticosteroids are controller therapy.

Type 2 diabetes: metformin is first-line unless contraindicated; HbA1c target is individualized, commonly below 7 percent.

Hyperkalemia: peaked T waves on ECG; calcium gluconate stabilizes myocardium while insulin-dextrose shifts potassium intracellularly.

Hypothyroidism: elevated TSH with low free T4; levothyroxine is taken on an empty stomach.

Peptic ulcer disease: Helicobacter pylori eradication with proton pump inhibitor plus two antibiotics.

Heart failure: reduced ejection fraction treated with ACE inhibitor, beta-blocker, and mineralocorticoid antagonist; loop diuretics relieve congestion.

Gout: negatively birefringent needle-shaped urate crystals; NSAIDs or colchicine treat acute attacks.

Pneumonia: CURB-65 score uses confusion, urea, respiratory rate, blood pressure, and age to guide admission.

Bowel anastomosis: adequate blood supply and tension-free repair are prerequisites; dehiscence presents with peritonitis and rising inflammatory markers.

Acute cholecystitis: right upper quadrant pain with Murphy sign; ultrasound shows wall thickening and pericholecystic fluid.

Testicular torsion: acute scrotal pain with high-riding testis and absent cremasteric reflex; detorsion within 6 h preserves viability.

Volvulus: sigmoid volvulus shows coffee-bean sign on plain film; sigmoidoscopy detorsion may be attempted if no gangrene.

Thyroid nodule: fine-needle aspiration cytology is initial evaluation for nodules over 1 cm with suspicious features.

Fracture management: open fractures require urgent debridement and antibiotics; tetanus prophylaxis is checked.

Anesthesia: spinal anesthesia blocks sympathetic fibers first, causing hypotension; preload with fluids mitigates it.

Postoperative fever: within 48 h consider atelectasis; days 3-5 consider urinary or wound infection; after 5 days consider abscess or deep vein thrombosis.

Labor stages: first stage from onset to full dilatation; second stage to delivery; third stage to placental expulsion.

Shoulder dystocia: McRoberts maneuver with suprapubic pressure first; avoid fundal pressure.

Gestational diabetes: screening with oral glucose tolerance test at 24-28 weeks; diet and insulin if targets unmet.

Placenta previa: painless vaginal bleeding in late pregnancy; avoid digital vaginal examination until localization by ultrasound.

Ovarian torsion: sudden unilateral pelvic pain with nausea; Doppler may be normal and surgery is diagnostic.

Polycystic ovary syndrome: Rotterdam criteria require two of ovulatory dysfunction, hyperandrogenism, and polycystic ovaries.

Menopause: defined retrospectively after 12 months of amenorrhea; FSH rises as ovarian follicles deplete.

Puerperal sepsis: fever and uterine tenderness after delivery; group A streptococcus is a feared cause.

Dehydration in children: reduced skin turgor, sunken eyes, and delayed capillary refill; oral rehydration solution is first-line for mild to moderate cases.

Neonatal resuscitation: initial steps are warmth, drying, and stimulation; positive pressure ventilation if apnea or heart rate below 100.

Febrile seizures: occur between 6 months and 6 years with fever and no intracranial infection; simple seizures last under 15 minutes.

Kernicterus: unconjugated bilirubin deposition in basal ganglia; risk rises with hemolysis and prematurity.

Acute epiglottitis: drooling, tripod posture, and muffled voice; avoid throat examination and secure airway.

Vitamin D deficiency: causes rickets with bowing and widened wrists; supplementation prevents in exclusively breastfed infants.

Cerebral palsy: nonprogressive motor disorder from prenatal or perinatal insult; spastic diplegia is commonest in preterm infants.

Hand-foot-and-mouth disease: coxsackievirus causes oral ulcers and vesicular rash on palms and soles.

Cranial nerves: facial nerve exits stylomastoid foramen; parotid tumors can damage it causing facial palsy.

Heart valves: aortic valve auscultated at right second intercostal space; mitral at apex in fifth intercostal space.

Lung lobes: right lung has three lobes and two fissures; left has two lobes and one fissure with lingula.

Liver segments: Couinaud classification divides liver into eight segments based on portal and hepatic venous anatomy.

Diaphragm: right crus arises from L1-L3; phrenic nerve roots C3-C5 provide motor supply.

Sciatic nerve: largest nerve in body, exits greater sciatic foramen below piriformis, supplies posterior thigh and most of leg.

Vertebral column: atlas has no body; axis has dens; cervical vertebrae have foramina transversaria for vertebral arteries.

Spleen: lies in left hypochondrium, related to ribs 9-11; supplied by splenic artery, a branch of celiac trunk.

Blood pressure equals cardiac output times total peripheral resistance; arterioles are chief resistance vessels.

Baroreceptor reflex: carotid sinus afferents travel in glossopharyngeal nerve; response to hypotension is sympathetic activation.

Lung volumes: functional residual capacity equals residual volume plus expiratory reserve; vital capacity equals inspiratory reserve plus tidal volume plus expiratory reserve.

Renin-angiotensin-aldosterone system: renin from juxtaglomerular cells converts angiotensinogen to angiotensin I; ACE converts it to angiotensin II.

Insulin lowers blood glucose by promoting cellular uptake and glycogen synthesis; glucagon raises it via glycogenolysis.

Skeletal muscle contraction: sliding filament theory; calcium binds troponin C to expose actin-binding sites.

Gastrointestinal motility: migrating motor complex sweeps small bowel during fasting; vagus stimulates gastric emptying.

Thermoregulation: hypothalamus anterior region controls heat loss; posterior region controls heat conservation.

Gluconeogenesis: occurs mainly in liver and kidney; key enzymes include pyruvate carboxylase and fructose-1,6-bisphosphatase.

Beta-oxidation defects: medium-chain acyl-CoA dehydrogenase deficiency causes hypoketotic hypoglycemia during fasting.

Cholesterol synthesis: HMG-CoA reductase is rate-limiting; statins inhibit it.

Vitamin C: cofactor for prolyl and lysyl hydroxylase in collagen synthesis; deficiency causes scurvy.

Thiamine: cofactor for pyruvate dehydrogenase and transketolase; deficiency causes beriberi and Wernicke encephalopathy.

DNA mutations: transition replaces purine with purine; transversion replaces purine with pyrimidine.

Restriction enzymes: recognize palindromic sequences and cleave DNA; used in recombinant DNA technology.

Glycogen storage disease type I: glucose-6-phosphatase deficiency causes fasting hypoglycemia and hepatomegaly.

Apoptosis: programmed cell death with cell shrinkage and chromatin condensation; caspases execute the process.

Cell injury: reversible injury shows swelling; irreversible injury shows membrane damage and mitochondrial dysfunction.

Thrombosis: Virchow triad comprises endothelial injury, stasis or turbulence, and hypercoagulability.

Embolism: pulmonary embolism from deep vein thrombosis; systemic embolism often from atrial fibrillation or endocarditis.

Cirrhosis: bridging fibrosis with regenerative nodules; complications include portal hypertension and hepatocellular carcinoma.

Glomerulonephritis: nephritic syndrome with hematuria, hypertension, and oliguria; post-streptococcal disease follows infection by 1-3 weeks.

Tuberculosis pathology: caseating granulomas with Langhans giant cells; acid-fast bacilli in sputum confirm.

Leukemia: acute lymphoblastic leukemia is commonest childhood malignancy; bone marrow blasts exceed 20 percent.

Opioids: act on mu receptors causing analgesia, respiratory depression, and miosis; naloxone reverses toxicity.

Benzodiazepines: enhance GABA-A receptor chloride conductance; flumazenil is the antagonist.

Digoxin: inhibits sodium-potassium ATPase, increasing intracellular calcium; toxicity shows yellow vision and arrhythmias.

Loop diuretics: inhibit sodium-potassium-2chloride cotransporter in thick ascending limb; cause hypokalemia and ototoxicity.

Thiazides: inhibit sodium-chloride cotransporter in distal convoluted tubule; cause hyperglycemia and hyperuricemia.

Aminoglycoside dosing: once-daily dosing reduces toxicity by exploiting concentration-dependent killing.

Antitubercular drugs: isoniazid causes peripheral neuropathy prevented by pyridoxine; rifampicin induces cytochrome P450.

NSAIDs: inhibit cyclooxygenase, reducing prostaglandin synthesis; cause gastric ulceration and renal impairment.

Clostridium tetani: gram-positive rod with terminal spores; tetanospasmin blocks inhibitory neurotransmitters causing spasm.

Clostridium perfringens: causes gas gangrene with crepitus; alpha toxin is lecithinase.

Salmonella typhi: causes enteric fever with rose spots and relative bradycardia; blood culture is positive in first week.

Neisseria meningitidis: gram-negative diplococcus; rifampicin prophylaxis for close contacts.

Herpes simplex virus: latent in sensory ganglia; type 2 causes genital lesions.

Human immunodeficiency virus: binds CD4 via gp120; viral load and CD4 count guide therapy.

Candida albicans: germ tube positive; causes oral thrush and vulvovaginitis.

Sterile technique: surgical hand scrub reduces transient and resident flora; gloves do not replace hand hygiene.

Informed consent: must be documented; emergency treatment may proceed without consent under necessity.

Age estimation: dental eruption and ossification centers help in medicolegal age determination.

Poisoning: organophosphate poisoning causes miosis, salivation, and bradycardia; atropine is the antidote.

Carbon monoxide poisoning: cherry-red lividity is a classic postmortem finding; carboxyhemoglobin confirms exposure.

Medical negligence: requires duty of care, breach, causation, and resulting damage.

Suicide risk: asking about suicidal ideation does not increase risk; direct questioning is appropriate.

Schizophrenia: positive symptoms include hallucinations and delusions; negative symptoms include flat affect and avolition.

Alcohol withdrawal: tremor, sweating, and seizures; benzodiazepines are first-line treatment.

Randomized controlled trial: randomization reduces selection bias; intention-to-treat analysis preserves comparability.

Confounding: a variable associated with both exposure and outcome distorts the observed association; adjust by stratification or regression.

Screening criteria: condition must be important, detectable early, and treatable with accepted tests.

Epidemic curve: describes time distribution of cases; point source gives a single peak.

Maternal mortality ratio: maternal deaths per 100,000 live births in a period.

Cold chain: vaccines stored at 2-8 degrees Celsius except oral polio vaccine which is kept frozen.

Disability-adjusted life year: combines years of life lost and years lived with disability.

Biostatistics: mean, median, and mode measure central tendency; standard deviation measures spread.

Chronic obstructive pulmonary disease: post-bronchodilator FEV1/FVC below 0.7 confirms obstruction; smoking cessation is the only intervention that slows decline.

Atrial fibrillation: irregularly irregular pulse with absent P waves; CHA2DS2-VASc guides anticoagulation.

Acute kidney injury: KDIGO criteria use rise in creatinine or fall in urine output; prerenal injury responds to volume.

Cirrhosis: Child-Pugh score uses bilirubin, albumin, INR, ascites, and encephalopathy to estimate prognosis.

Rheumatoid arthritis: symmetric small joint involvement with anti-cyclic citrullinated peptide antibodies; methotrexate is first-line.

Meningitis: neck stiffness and photophobia; bacterial meningitis requires immediate empiric antibiotics after blood culture.

Hypoglycemia: Whipple triad of symptoms, low glucose, and relief with glucose administration.

Pleural effusion: Light criteria separate exudate from transudate using protein and lactate dehydrogenase ratios.

Trauma primary survey: airway, breathing, circulation, disability, exposure; cervical spine immobilized until cleared.

Pneumothorax: tension pneumothorax causes tracheal deviation and hypotension; needle decompression precedes chest drain.

Appendectomy: laparoscopic approach is preferred; perforation with peritonitis requires washout and antibiotics.

Hernia: indirect inguinal hernia passes lateral to inferior epigastric vessels; femoral hernia is commonest in elderly women and risks strangulation.

Burns: rule of nines assigns 9 percent to each arm and each head, 18 percent to each leg and anterior trunk.

Colorectal cancer: right-sided tumors present with anemia; left-sided with obstruction; carcinoembryonic antigen monitors recurrence.

Prostate: benign hyperplasia causes hesitancy and nocturia; prostate-specific antigen is raised in cancer.

Fluid management: crystalloids for resuscitation; blood products for significant hemorrhage in balanced ratios.

Antenatal care: folic acid 400 micrograms daily before conception reduces neural tube defects.

Fetal presentation: breech at term may be managed by external cephalic version after 36 weeks.

Preterm labor: tocolysis with nifedipine buys time for antenatal corticosteroids which accelerate fetal lung maturity.

Multiple pregnancy: monochorionic twins risk twin-to-twin transfusion syndrome due to shared placental circulation.

Endometriosis: cyclical pelvic pain and dyspareunia; laparoscopy with biopsy is diagnostic.

Cervical intraepithelial neoplasia: colposcopy with biopsy grades lesions; high-grade lesions treated by excision.

Menorrhagia: commonest cause in reproductive years is dysfunctional uterine bleeding; endometrial biopsy excludes hyperplasia.

Ovarian cancer: CA-125 is a marker but not diagnostic; surgery with staging is initial management.

Neonatal sepsis: risk factors include prolonged rupture of membranes and maternal fever; empiric antibiotics after cultures.

Failure to thrive: weight below third percentile or crossing two major centile lines; evaluate feeding and organic causes.

Congenital heart disease: ventricular septal defect is commonest; cyanotic lesions include tetralogy of Fallot.

Down syndrome: trisomy 21 with hypotonia, upslanting palpebral fissures, and single palmar crease; screen for cardiac defects.

Bronchiolitis: respiratory syncytial virus causes wheeze and crackles in infants under 1 year; supportive care with oxygen.

Nephroblastoma: Wilms tumor presents with abdominal mass in children under 5; nephrectomy with chemotherapy.

Asthma in children: recurrent wheeze responsive to bronchodilators; inhaled corticosteroids for persistent symptoms.

Newborn screening: heel prick blood test detects congenital hypothyroidism and phenylketonuria.

Upper limb: radial nerve supplies extensor compartment; humeral shaft fracture causes wrist drop.

Carpal bones: scaphoid fracture risks avascular necrosis; tenderness in anatomical snuffbox.

Abdominal aorta: bifurcates at L4 into common iliac arteries; aneurysm commonly infrarenal.

Pelvis: sacroiliac joint transmits weight to lower limbs; pubic symphysis is a secondary cartilaginous joint.

Cranial fossae: middle fossa contains pituitary gland in sella turcica; foramen ovale transmits mandibular nerve.

Lymphatics: axillary nodes drain upper limb and breast; inguinal nodes drain lower limb and perineum.

Muscles: deltoid abducts arm from 15 to 90 degrees; supraspinatus initiates abduction.

Nerve injuries: ulnar nerve at elbow causes claw hand; median nerve at wrist causes thenar wasting.

Cardiac cycle: systole includes isovolumetric contraction and ejection; diastole includes filling and isovolumetric relaxation.

ECG intervals: PR 0.12-0.20 s, QRS under 0.12 s, QT varies with heart rate.

Renal clearance: clearance equals urine concentration times urine volume divided by plasma concentration.

Respiratory exchange: alveolar ventilation equals tidal volume minus dead space times respiratory rate.

Endocrine feedback: negative feedback maintains hormone levels; thyroid hormone inhibits TSH secretion.

Muscle types: skeletal muscle is voluntary and striated; smooth muscle is involuntary and nonstriated.

Hemostasis: platelet plug formation followed by coagulation cascade and fibrinolysis.

Acid-base: Henderson-Hasselbalch equation relates pH to bicarbonate and carbon dioxide; compensation is respiratory or renal.

Protein structure: primary sequence determined by peptide bonds; secondary structure from hydrogen bonds; tertiary from folding.

Collagen: contains glycine, proline, and hydroxyproline; vitamin C required for hydroxylation.

Hemoglobin: adult hemoglobin has two alpha and two beta chains; fetal hemoglobin has higher oxygen affinity.

Lipoproteins: low-density lipoprotein transports cholesterol to tissues; high-density lipoprotein transports it to liver.

Uric acid: end product of purine catabolism; elevated in gout and Lesch-Nyhan syndrome.

Enzyme inhibition: competitive inhibitors raise Km without changing Vmax; noncompetitive inhibitors lower Vmax.

ATP production: complete oxidation of one glucose yields about 30-32 ATP.

DNA repair: mismatch repair defects cause Lynch syndrome; nucleotide excision repair defects cause xeroderma pigmentosum.

Wound healing: primary intention in clean wounds; secondary intention with granulation tissue in open wounds.

Metaplasia: reversible change of one mature cell type to another; Barrett esophagus is columnar metaplasia.

Dysplasia: disordered growth with atypia; may progress to carcinoma in situ.

Amyloidosis: extracellular deposition of misfolded proteins; apple-green birefringence under polarized light with Congo red.

Hypertrophy: increase in cell size; hyperplasia is increase in cell number; both are adaptive responses.

Shock: hypovolemic, cardiogenic, distributive, and obstructive types; distributive includes septic and anaphylactic shock.

Tumor markers: alpha-fetoprotein in hepatocellular carcinoma; carcinoembryonic antigen in colorectal cancer.

Autoimmune disease: loss of self-tolerance; type 1 diabetes results from destruction of pancreatic beta cells.