NPMCN Primary cheat sheet

Brachial plexus roots C5–T1; Erb's palsy (C5–C6) gives waiter's tip, Klumpke's (C8–T1) gives claw hand with Horner's syndrome.

Femoral triangle boundaries: inguinal ligament superiorly, sartorius laterally, adductor longus medially; floor is iliopsoas and pectineus.

Axillary nerve (C5–C6) winds round surgical neck of humerus; injury causes deltoid wasting and loss of sensation over the deltoid badge area.

Median nerve supplies thenar muscles via recurrent branch; carpal tunnel syndrome spares the palm because palmar cutaneous branch arises proximally.

Recurrent laryngeal nerve: left hooks under aortic arch, right under right subclavian artery; both ascend in tracheo-oesophageal groove.

Inguinal canal: deep ring lateral to inferior epigastric artery, superficial ring above and medial to pubic tubercle; indirect hernia is lateral to the inferior epigastric vessels.

Portal vein forms behind the neck of pancreas from superior mesenteric and splenic veins; it drains to hepatic sinusoids then hepatic veins into IVC.

Circle of Willis: anterior communicating, paired anterior cerebral, internal carotid, posterior communicating, posterior cerebral; posterior communicating connects carotid to posterior cerebral.

Cardiac output = heart rate × stroke volume; Fick principle: CO = oxygen consumption ÷ arteriovenous oxygen difference.

Frank–Starling law: increased end-diastolic volume increases stroke volume up to a plateau; contractility shifts the curve.

Mean arterial pressure ≈ diastolic pressure + one-third of pulse pressure.

Glomerular filtration rate = Kf × net filtration pressure; net pressure = glomerular capillary pressure − (plasma oncotic pressure + Bowman's capsule pressure).

Oxygen–haemoglobin curve shifts right (reduced affinity) with increased 2,3-DPG, acidosis, raised temperature, raised CO2; shifts left with fetal haemoglobin and carboxyhaemoglobin.

Resting membrane potential is set mainly by potassium permeability; the Na+/K+-ATPase extrudes 3 Na+ for 2 K+.

Insulin lowers blood glucose by promoting GLUT4 translocation in muscle and adipose; glucagon raises it via hepatic glycogenolysis and gluconeogenesis.

Surfactant from type II pneumocytes lowers alveolar surface tension, reducing Laplace pressure and preventing alveolar collapse; deficiency causes respiratory distress syndrome.

Glycolysis yields net 2 ATP and 2 NADH per glucose; pyruvate dehydrogenase produces acetyl-CoA plus NADH, linking to the Krebs cycle.

Rate-limiting enzymes: phosphofructokinase-1 (glycolysis), citrate synthase (Krebs), fructose-1,6-bisphosphatase (gluconeogenesis), HMG-CoA reductase (cholesterol synthesis).

Urea cycle: carbamoyl phosphate + ornithine → citrulline → argininosuccinate → arginine → urea; rate-limiting enzyme carbamoyl phosphate synthetase I.

Vitamin C is required for proline and lysine hydroxylation in collagen; deficiency causes scurvy with poor wound healing and bleeding gums.

Phenylketonuria results from phenylalanine hydroxylase deficiency; untreated causes intellectual disability, and treatment is dietary phenylalanine restriction.

DNA replication is semiconservative; RNA synthesis uses uracil instead of thymine; reverse transcriptase makes DNA from an RNA template.

Competitive inhibitors raise apparent Km without changing Vmax; non-competitive inhibitors lower Vmax without changing Km.

Ketone bodies (acetoacetate, beta-hydroxybutyrate, acetone) are produced in hepatic mitochondria during prolonged fasting and used by brain and muscle.

Acute inflammation: vasodilatation, increased vascular permeability, neutrophil emigration via margination, rolling, adhesion, transmigration and chemotaxis.

Granulomas consist of epithelioid histiocytes with Langhans giant cells; caseating granulomas suggest tuberculosis.

Malignant tumours show invasion, metastasis, cellular pleomorphism, hyperchromasia, high nuclear-to-cytoplasmic ratio and atypical mitoses.

Virchow's triad for thrombosis: endothelial injury, abnormal blood flow (stasis or turbulence), hypercoagulability.

Left ventricular failure causes pulmonary oedema and congestion; right ventricular failure causes systemic congestion, hepatomegaly and peripheral oedema.

Nephrotic syndrome: proteinuria >3.5 g/day, hypoalbuminaemia, oedema, hyperlipidaemia; nephritic syndrome features haematuria and hypertension.

Myocardial infarction: coagulative necrosis begins 6–12 hours, neutrophils peak 1–3 days, granulation tissue by 1–2 weeks, fibrous scar by 6–8 weeks.

Cervical carcinoma arises at the transformation zone; squamous cell carcinoma is commonest and is linked to high-risk human papillomavirus types 16 and 18.

First-order kinetics: constant fraction eliminated per unit time; zero-order kinetics: constant amount eliminated, seen with phenytoin, ethanol and high-dose aspirin.

Half-life = 0.693 × volume of distribution ÷ clearance; steady state is reached after about 4–5 half-lives.

Bioavailability = (area under curve oral ÷ area under curve intravenous) × 100; intravenous bioavailability is 100% by definition.

Competitive antagonists shift the dose–response curve right without lowering maximal response; non-competitive antagonists reduce maximal response.

Aminoglycosides bind the 30S ribosomal subunit, are nephrotoxic and ototoxic, and require dose adjustment in renal impairment.

Beta-blockers reduce heart rate and myocardial oxygen demand; they are used in angina and heart failure but can precipitate bronchospasm in asthma.

Paracetamol overdose depletes glutathione; N-acetylcysteine replenishes it and is most effective within 8–10 hours of ingestion.

Drugs inducing cytochrome P450 (rifampicin, phenytoin, carbamazepine) lower levels of co-administered drugs; inhibitors (erythromycin, ketoconazole) raise them.

Gram-positive bacteria retain crystal violet due to thick peptidoglycan; Gram-negative organisms have an outer membrane with lipopolysaccharide.

IgM is the first antibody in primary infection and is pentameric; IgG crosses the placenta; IgA is secretory; IgE mediates type I hypersensitivity.

Type I hypersensitivity is IgE-mediated mast cell degranulation; type IV is T-cell mediated and delayed, as in tuberculin reaction and contact dermatitis.

Active immunity follows vaccination or infection and is long-lasting; passive immunity from maternal antibody or immunoglobulin is immediate but transient.

Hepatitis B is a DNA virus transmitted by blood and body fluids; hepatitis A and E spread faeco-orally; C spreads parenterally.

Mycobacterium tuberculosis is acid-fast due to mycolic acids in the cell wall and is cultured on Löwenstein–Jensen medium.

Staphylococcus aureus is coagulase-positive, catalase-positive and forms clusters; Streptococcus pyogenes is bacitracin-sensitive and beta-haemolytic.

Sterilisation kills all microorganisms including spores; disinfection reduces pathogens on inanimate objects but may not kill spores.

Incidence = new cases ÷ population at risk per unit time; prevalence = all existing cases ÷ total population at a point or period.

Prevalence ≈ incidence × average duration of disease when disease frequency is low.

Sensitivity = true positives ÷ (true positives + false negatives); specificity = true negatives ÷ (true negatives + false positives).

Positive predictive value depends on prevalence; a test with high sensitivity is best for screening, and high specificity for confirmation.

Relative risk is used in cohort studies; odds ratio estimates risk in case–control studies.

Attributable risk = incidence in exposed − incidence in unexposed; it quantifies excess disease due to exposure.

Herd immunity threshold depends on basic reproduction number: threshold = 1 − 1/R0.

Levels of prevention: primary (pre-exposure), secondary (early detection and treatment), tertiary (limitation of disability and rehabilitation).

Informed consent requires capacity, adequate information and voluntariness; a competent adult may refuse treatment even if the decision seems unwise.

Four principles of biomedical ethics: autonomy, beneficence, non-maleficence and justice.

Confidentiality may be breached only where legally required or where there is a serious risk to others, and disclosure should be limited to what is necessary.

Grief stages described by Kübler-Ross: denial, anger, bargaining, depression and acceptance; they are not strictly sequential.

Sick role (Parsons) exempts the ill person from normal duties but obliges them to seek competent help and want to recover.

Health belief model constructs: perceived susceptibility, perceived severity, perceived benefits, perceived barriers and cues to action.

Transference is the patient's projection of feelings onto the doctor; countertransference is the doctor's emotional reaction to the patient.

Capacity assessment covers understanding, retention, reasoning and communication of the decision; delirium or severe cognitive impairment may negate it.

ABCDE approach: airway, breathing, circulation, disability, exposure; reassess after every intervention.

Shock features: tachycardia, hypotension, cool peripheries, prolonged capillary refill, oliguria and altered consciousness.

Acute severe asthma: inability to complete sentences, respiratory rate >25/min, pulse >110/min, peak flow 33–50% predicted; silent chest is a life-threatening sign.

Hypoglycaemia is blood glucose <3.9 mmol/L with sweating, tremor and confusion; treat with oral glucose if conscious, intravenous dextrose if not.

Diabetic ketoacidosis: glucose >11 mmol/L, ketonaemia, pH <7.3, bicarbonate <15 mmol/L; treat with fluids, insulin infusion and potassium replacement.

Cushing's triad of raised intracranial pressure: hypertension with widened pulse pressure, bradycardia and irregular respiration.

Meningitis: neck stiffness, photophobia, Kernig's and Brudzinski's signs; do not delay antibiotics for lumbar puncture in suspected bacterial meningitis.

Acute abdomen red flags: rigidity, rebound tenderness, absent bowel sounds, haemodynamic instability; require urgent surgical review.

Mean, median and mode: the median is preferred for skewed data; the mean is sensitive to outliers.

Standard deviation describes spread of individual values; standard error of the mean = SD ÷ √n and describes precision of the sample mean.

95% confidence interval for a mean ≈ mean ± 1.96 × standard error; a wide interval indicates imprecision.

Type I error is rejecting a true null hypothesis (alpha); type II error is failing to reject a false null (beta); power = 1 − beta.

p < 0.05 means the observed result would be unlikely if the null hypothesis were true; it does not measure effect size.

Chi-square test compares proportions in categorical data; t-test compares means; ANOVA compares three or more group means.

Randomisation reduces selection bias; blinding reduces measurement and observer bias; confounding is addressed by randomisation or adjustment in analysis.

Sample size increases with larger expected effect variability and desired power, and decreases with larger detectable effect size.

Median nerve injury at the wrist spares palmar sensation; injury at the elbow causes the hand of benediction.

The diaphragm is supplied by the phrenic nerve (C3, C4, C5); irritation refers pain to the shoulder tip.

The femoral nerve (L2–L4) supplies the quadriceps; injury abolishes the knee jerk.

The sciatic nerve divides into tibial and common peroneal; common peroneal injury causes foot drop.

The thoracic duct drains into the left subclavian vein at the junction with the internal jugular.

The appendix base lies at the junction of the lateral and middle thirds of the line joining the umbilicus to the anterior superior iliac spine.

The facial nerve (VII) supplies muscles of facial expression; upper motor neuron lesions spare the forehead.

The kidney lies retroperitoneally at T12–L3; the right kidney is lower because of the liver.

Cardiac output = heart rate × stroke volume; Fick principle: CO = oxygen consumption ÷ arteriovenous oxygen difference.

Frank–Starling law: increased end-diastolic volume increases stroke volume up to a plateau; contractility shifts the curve.

Mean arterial pressure ≈ diastolic pressure + one-third of pulse pressure.

Glomerular filtration rate = Kf × net filtration pressure; net pressure = glomerular capillary pressure − (plasma oncotic pressure + Bowman's capsule pressure).

Oxygen–haemoglobin curve shifts right with increased 2,3-DPG, acidosis, raised temperature and raised CO2; shifts left with fetal haemoglobin.

Resting membrane potential is set mainly by potassium permeability; the Na+/K+-ATPase extrudes 3 Na+ for 2 K+.

Insulin lowers blood glucose by promoting GLUT4 translocation in muscle and adipose.

Surfactant from type II pneumocytes lowers alveolar surface tension and prevents alveolar collapse.

Glycolysis yields net 2 ATP and 2 NADH per glucose; pyruvate dehydrogenase produces acetyl-CoA plus NADH.

Rate-limiting enzymes: phosphofructokinase-1 (glycolysis), citrate synthase (Krebs), HMG-CoA reductase (cholesterol synthesis).

Urea cycle: carbamoyl phosphate + ornithine → citrulline → argininosuccinate → arginine → urea.

Vitamin C is required for proline and lysine hydroxylation in collagen; deficiency causes scurvy.

Phenylketonuria results from phenylalanine hydroxylase deficiency; treatment is dietary phenylalanine restriction.

Competitive inhibitors raise apparent Km without changing Vmax; non-competitive inhibitors lower Vmax.

Ketone bodies are produced in hepatic mitochondria during prolonged fasting and used by brain and muscle.

DNA replication is semiconservative; RNA synthesis uses uracil instead of thymine.

Acute inflammation: vasodilatation, increased vascular permeability and neutrophil emigration.

Granulomas consist of epithelioid histiocytes with Langhans giant cells; caseation suggests tuberculosis.

Malignant tumours show invasion, metastasis, pleomorphism, hyperchromasia and atypical mitoses.

Virchow's triad: endothelial injury, abnormal blood flow and hypercoagulability.

Myocardial infarction: coagulative necrosis begins 6–12 hours, neutrophils peak 1–3 days, fibrous scar by 6–8 weeks.

Nephrotic syndrome: proteinuria >3.5 g/day, hypoalbuminaemia, oedema and hyperlipidaemia.

Left ventricular failure causes pulmonary oedema; right ventricular failure causes systemic congestion.

Cervical carcinoma arises at the transformation zone and is linked to HPV types 16 and 18.

First-order kinetics: constant fraction eliminated per unit time; zero-order kinetics: constant amount, as with phenytoin and ethanol.

Half-life = 0.693 × volume of distribution ÷ clearance; steady state is reached after about 4–5 half-lives.

Bioavailability = (oral area under curve ÷ intravenous area under curve) × 100; intravenous bioavailability is 100%.

Competitive antagonists shift the dose–response curve right without lowering maximal response.

Aminoglycosides bind the 30S subunit and are nephrotoxic and ototoxic.

Paracetamol overdose depletes glutathione; N-acetylcysteine replenishes it and is most effective within 8–10 hours.

Enzyme inducers (rifampicin, phenytoin) lower levels of co-administered drugs; inhibitors (erythromycin) raise them.

Beta-blockers reduce myocardial oxygen demand but can precipitate bronchospasm in asthma.

Gram-positive bacteria retain crystal violet due to thick peptidoglycan; Gram-negatives have an outer membrane with lipopolysaccharide.

IgM is the first antibody in primary infection; IgG crosses the placenta; IgA is secretory; IgE mediates type I hypersensitivity.

Type I hypersensitivity is IgE-mediated mast cell degranulation; type IV is T-cell mediated and delayed.

Active immunity follows vaccination or infection and is long-lasting; passive immunity is immediate but transient.

Hepatitis B is a DNA virus spread by blood and body fluids; hepatitis A and E spread faeco-orally.

Mycobacterium tuberculosis is acid-fast due to mycolic acids and is cultured on Löwenstein–Jensen medium.

Staphylococcus aureus is coagulase-positive and catalase-positive; Streptococcus pyogenes is bacitracin-sensitive.

Sterilisation kills all microorganisms including spores; disinfection may not kill spores.

Incidence = new cases ÷ population at risk per unit time; prevalence = all existing cases ÷ total population.

Prevalence ≈ incidence × average duration when disease frequency is low.

Sensitivity = true positives ÷ (true positives + false negatives); specificity = true negatives ÷ (true negatives + false positives).

Positive predictive value depends on prevalence; high sensitivity suits screening and high specificity suits confirmation.

Relative risk is used in cohort studies; odds ratio estimates risk in case–control studies.

Attributable risk = incidence in exposed − incidence in unexposed.

Herd immunity threshold = 1 − 1/R0.

Primary prevention is pre-exposure; secondary is early detection; tertiary limits disability.

Informed consent requires capacity, adequate information and voluntariness.

Four principles of biomedical ethics: autonomy, beneficence, non-maleficence and justice.

Confidentiality may be breached only where legally required or where there is serious risk to others.

Kübler-Ross stages: denial, anger, bargaining, depression and acceptance; they are not strictly sequential.

Sick role (Parsons) exempts the ill from normal duties but obliges them to seek help and want to recover.

Health belief model constructs: perceived susceptibility, severity, benefits, barriers and cues to action.

Transference is the patient's projection onto the doctor; countertransference is the doctor's reaction.

Capacity assessment covers understanding, retention, reasoning and communication.

ABCDE approach: airway, breathing, circulation, disability, exposure; reassess after every intervention.

Shock features: tachycardia, hypotension, cool peripheries, prolonged capillary refill and oliguria.

Acute severe asthma: inability to complete sentences, respiratory rate >25/min, pulse >110/min; silent chest is life-threatening.

Hypoglycaemia is blood glucose <3.9 mmol/L; treat with oral glucose if conscious, intravenous dextrose if not.

Diabetic ketoacidosis: glucose >11 mmol/L, ketonaemia, pH <7.3, bicarbonate <15 mmol/L.

Cushing's triad of raised intracranial pressure: hypertension with widened pulse pressure, bradycardia and irregular respiration.

Do not delay antibiotics for lumbar puncture in suspected bacterial meningitis.

Acute abdomen red flags: rigidity, rebound tenderness and haemodynamic instability need urgent surgical review.

The median is preferred for skewed data; the mean is sensitive to outliers.

Standard error of the mean = SD ÷ √n and describes precision of the sample mean.

95% confidence interval for a mean ≈ mean ± 1.96 × standard error.

Type I error is rejecting a true null (alpha); type II error is failing to reject a false null (beta); power = 1 − beta.

p < 0.05 does not measure effect size.

Chi-square compares proportions; t-test compares means; ANOVA compares three or more group means.

Randomisation reduces selection bias; blinding reduces measurement and observer bias.

Sample size increases with larger variability and desired power, and decreases with larger detectable effect size.