STUDENT’S CORNER • NEW MODULE
Pathophysiology
100 selected high-yield topics explained from the underlying physiologic disturbance to organ dysfunction and clinical expression. Horizontal arrow algorithms are used wherever they clarify the sequence. The first 2 topics are free; Topics 3–100 open with Members Access.
✓ TOPICS 1–2 FREE🔒 TOPICS 3–100 MEMBERSRED HEADINGS • BLACK TEXT • GREEN BACKGROUND
TOPIC 001 • Cardiovascular
Heart Failure
Myocardial injury or chronic pressure/volume overload → ↓ effective stroke volume → baroreceptor unloading → sympa…
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TOPIC 002 • Endocrine & Metabolic
Type 2 Diabetes Mellitus
Genetic susceptibility + visceral adiposity/inactivity → insulin resistance in muscle/liver/adipose tissue → compe…
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TOPIC 003 • Cardiovascular
Acute Myocardial Infarction
Atherosclerotic plaque disruption → platelet adhesion/activation + thrombin generation → acute coronary thrombus →…
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TOPIC 004 • Cardiovascular
Hypertension
Genetic/environmental factors → renal Na⁺ handling abnormality + sympathetic/RAAS activation + endothelial dysfunc…
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TOPIC 005 • Cardiovascular
Atrial Fibrillation
Atrial substrate/remodelling + triggers (often pulmonary veins) → multiple re-entry wavelets/rapid focal activity …
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TOPIC 006 • Cardiovascular
Aortic Stenosis
Progressive valvular calcification/fibrosis → fixed LV outflow obstruction → ↑ transvalvular gradient → chronic LV…
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TOPIC 007 • Cardiovascular
Mitral Regurgitation
Leaflet/chordal/papillary/LV geometric abnormality → systolic backflow LV→LA → LA volume overload + ↑ v-wave → pul…
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TOPIC 008 • Cardiovascular
Mitral Stenosis
Rheumatic commissural fusion/leaflet thickening → narrowed mitral orifice → diastolic LA→LV obstruction → ↑ LA pre…
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TOPIC 009 • Cardiovascular
Cardiogenic Shock
Severe pump failure → ↓ stroke volume/cardiac output → hypotension → ↓ coronary perfusion → worsening myocardial i…
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TOPIC 010 • Cardiovascular
Pericardial Tamponade
Rapid pericardial fluid accumulation → ↑ intrapericardial pressure → impaired chamber filling (RA/RV first) → ↓ ve…
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TOPIC 011 • Respiratory
Acute Pulmonary Embolism
Venous thrombus embolisation → pulmonary arterial obstruction + vasoconstrictor release → abrupt ↑ pulmonary vascu…
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TOPIC 012 • Respiratory
COPD
Chronic inhalational injury → airway inflammation + mucus hypersecretion + small-airway fibrosis + emphysematous a…
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TOPIC 013 • Respiratory
Bronchial Asthma
Trigger exposure → Th2/ILC2 inflammation → IgE/mast-cell activation + eosinophilic mediators → bronchoconstriction…
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TOPIC 014 • Respiratory
Community-Acquired Pneumonia
Pathogen reaches lower respiratory tract → evades host clearance → alveolar macrophage activation → cytokine-drive…
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TOPIC 015 • Respiratory
ARDS
Direct/indirect inflammatory insult → diffuse alveolar-capillary endothelial and epithelial injury → ↑ permeabilit…
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TOPIC 016 • Respiratory
Pleural Effusion
Imbalance between pleural fluid formation and lymphatic clearance → fluid accumulation in pleural space → lung com…
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TOPIC 017 • Respiratory
Pneumothorax
Air enters pleural space → loss of negative intrapleural pressure → ipsilateral lung recoil/collapse → reduced ven…
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TOPIC 018 • Respiratory
Interstitial Lung Disease / Pulmonary Fibrosis
Repeated alveolar epithelial injury → aberrant wound repair → fibroblast activation + myofibroblast proliferation …
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TOPIC 019 • Respiratory
Obstructive Sleep Apnoea
Sleep-related pharyngeal collapsibility + reduced dilator tone → recurrent upper-airway obstruction → intermittent…
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TOPIC 020 • Renal
Acute Kidney Injury
Renal hypoperfusion, intrinsic nephron injury or obstruction → abrupt fall in GFR → retention of nitrogenous waste…
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TOPIC 021 • Renal
Chronic Kidney Disease
Nephron loss → compensatory hyperfiltration in remaining nephrons → glomerular hypertension → proteinuria + mesang…
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TOPIC 022 • Renal
Nephrotic Syndrome
Podocyte/GBM filtration-barrier injury → massive albuminuria → hypoalbuminaemia → ↓ plasma oncotic pressure + rena…
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TOPIC 023 • Renal
Nephritic Syndrome / Glomerulonephritis
Immune-mediated glomerular inflammation → capillary-wall injury + leukocyte proliferation → haematuria + reduced f…
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TOPIC 024 • Renal
Diabetic Nephropathy
Chronic hyperglycaemia → AGE formation + oxidative stress + RAAS/TGF-β signalling → afferent dilation/efferent con…
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TOPIC 025 • Renal
Hyperkalaemia in Renal Failure
↓ GFR + impaired distal K⁺ secretion ± hypoaldosteronism/acidosis → extracellular K⁺ accumulation → resting membra…
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TOPIC 026 • Endocrine & Metabolic
SIADH
Inappropriate ADH effect despite low/normal osmolality → collecting-duct water reabsorption → dilutional hyponatra…
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TOPIC 027 • Endocrine & Metabolic
Diabetic Ketoacidosis
Absolute/marked insulin deficiency + excess glucagon/catecholamines/cortisol/GH → ↑ gluconeogenesis/glycogenolysis…
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TOPIC 028 • Endocrine & Metabolic
Hyperosmolar Hyperglycaemic State
Relative insulin deficiency → severe hyperglycaemia without major ketogenesis → profound osmotic diuresis → extrem…
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TOPIC 029 • Endocrine & Metabolic
Hypoglycaemia
Plasma glucose falls → ↓ insulin + ↑ glucagon/adrenaline → autonomic warning symptoms; further decline → inadequat…
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TOPIC 030 • Endocrine & Metabolic
Hyperthyroidism / Thyrotoxicosis
Excess T3/T4 action → ↑ nuclear transcription + mitochondrial activity → ↑ basal metabolic rate and thermogenesis;…
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TOPIC 031 • Endocrine & Metabolic
Hypothyroidism
Deficient thyroid hormone action → ↓ metabolic gene transcription and mitochondrial activity → ↓ thermogenesis/ene…
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TOPIC 032 • Endocrine & Metabolic
Primary Hyperparathyroidism
Autonomous PTH excess → ↑ bone resorption + ↑ renal Ca²⁺ reabsorption + ↓ renal phosphate reabsorption + ↑ calcitr…
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TOPIC 033 • Endocrine & Metabolic
Cushing Syndrome
Chronic glucocorticoid excess → ↑ gluconeogenesis + insulin resistance + protein catabolism + lipolysis/redistribu…
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TOPIC 034 • Endocrine & Metabolic
Addison Disease / Primary Adrenal Insufficiency
Adrenal cortex destruction → ↓ cortisol + ↓ aldosterone → loss of vascular tone and stress response + renal Na⁺ wa…
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TOPIC 035 • Endocrine & Metabolic
Acromegaly
GH-secreting pituitary adenoma → ↑ IGF-1 + direct GH metabolic effects → soft-tissue/bone overgrowth + insulin res…
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TOPIC 036 • Endocrine & Metabolic
Metabolic Syndrome
Visceral adiposity → adipocyte hypertrophy/inflammation + excess free fatty acids → insulin resistance → compensat…
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TOPIC 037 • Endocrine & Metabolic
Obesity
Chronic positive energy balance + genetic/neuroendocrine susceptibility → adipocyte hypertrophy/hyperplasia → lept…
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TOPIC 038 • Gastroenterology & Hepatology
Non-alcoholic Fatty Liver Disease / MASLD
Insulin resistance + excess caloric/free-fatty-acid flux → hepatic triglyceride accumulation → lipotoxicity + oxid…
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TOPIC 039 • Gastroenterology & Hepatology
Alcohol-related Liver Disease
Ethanol metabolism → acetaldehyde + excess NADH + ROS → steatosis + mitochondrial/ER injury → gut-derived endotoxi…
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TOPIC 040 • Gastroenterology & Hepatology
Cirrhosis and Portal Hypertension
Chronic hepatocyte injury → fibrosis + regenerative nodules → ↑ intrahepatic vascular resistance; splanchnic vasod…
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TOPIC 041 • Gastroenterology & Hepatology
Hepatic Encephalopathy
Liver failure/portosystemic shunting → impaired ammonia and toxin clearance → astrocyte glutamine accumulation + a…
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TOPIC 042 • Gastroenterology & Hepatology
Ascites in Cirrhosis
Portal hypertension + splanchnic vasodilatation → ↓ effective arterial blood volume → RAAS/SNS/ADH activation → re…
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TOPIC 043 • Gastroenterology & Hepatology
Acute Pancreatitis
Acinar injury/duct obstruction → premature intrapancreatic trypsin activation → autodigestion + local inflammation…
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TOPIC 044 • Gastroenterology & Hepatology
Chronic Pancreatitis
Recurrent pancreatic injury → persistent inflammation + stellate-cell activation → fibrosis/duct distortion/calcif…
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TOPIC 045 • Gastroenterology & Hepatology
Peptic Ulcer Disease
Failure of gastroduodenal mucosal defence relative to acid-pepsin injury → epithelial damage → ulceration; commonl…
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TOPIC 046 • Gastroenterology & Hepatology
GERD
Transient/incompetent LES relaxation + pressure gradient/hiatal hernia → reflux of gastric contents → impaired oes…
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TOPIC 047 • Gastroenterology & Hepatology
Inflammatory Bowel Disease
Genetic susceptibility + altered microbiome + epithelial-barrier dysfunction → inappropriate mucosal immune activa…
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TOPIC 048 • Gastroenterology & Hepatology
Coeliac Disease
Gluten-derived gliadin reaches small-bowel mucosa → tissue transglutaminase deamidation → HLA-DQ2/DQ8 presentation…
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TOPIC 049 • Hematology
Iron Deficiency Anaemia
Negative iron balance → depletion of storage ferritin → iron-restricted erythropoiesis → impaired haem synthesis →…
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TOPIC 050 • Hematology
Megaloblastic Anaemia
Vitamin B12 or folate deficiency → impaired thymidylate/DNA synthesis → nuclear maturation lag despite preserved c…
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TOPIC 051 • Hematology
Haemolytic Anaemia
Premature RBC destruction → ↓ RBC lifespan → tissue hypoxia → ↑ erythropoietin and reticulocytosis; haem breakdown…
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TOPIC 052 • Hematology
Sickle Cell Disease
β-globin mutation → HbS formation → deoxygenation-induced HbS polymerisation → RBC sickling/dehydration → membrane…
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TOPIC 053 • Hematology
Thalassaemia
Reduced α- or β-globin synthesis → globin-chain imbalance → precipitation of unmatched chains → ineffective erythr…
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TOPIC 054 • Hematology
Immune Thrombocytopenia
Loss of immune tolerance → IgG autoantibodies against platelet glycoproteins ± cytotoxic T-cell effects → splenic …
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TOPIC 055 • Hematology
DIC
Systemic tissue factor/endothelial activation → widespread thrombin generation → fibrin microthrombi → consumption…
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TOPIC 056 • Hematology
Acute Leukemia
Acquired mutations in haematopoietic progenitor → maturation arrest + uncontrolled clonal blast proliferation → ma…
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TOPIC 057 • Hematology
Multiple Myeloma
Clonal plasma-cell proliferation → monoclonal immunoglobulin/light chains + marrow cytokine effects → osteoclast a…
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TOPIC 058 • Neurology
Ischaemic Stroke
Cerebral arterial occlusion → abrupt fall in regional blood flow → ATP failure → ion-pump failure/depolarisation →…
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TOPIC 059 • Neurology
Intracerebral Haemorrhage
Small-vessel rupture → blood enters brain parenchyma → direct tissue disruption + mass effect → ↑ ICP; thrombin/ha…
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TOPIC 060 • Neurology
Subarachnoid Haemorrhage
Ruptured intracranial aneurysm → arterial blood into subarachnoid space → abrupt ↑ ICP + meningeal irritation → re…
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TOPIC 061 • Neurology
Epileptic Seizure
Imbalance favouring neuronal excitation over inhibition → hypersynchronous cortical firing → local or network prop…
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TOPIC 062 • Neurology
Parkinson Disease
Progressive degeneration of substantia nigra dopaminergic neurons + α-synuclein pathology → ↓ striatal dopamine → …
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TOPIC 063 • Neurology
Alzheimer Disease
Amyloid-β accumulation + tau hyperphosphorylation → synaptic dysfunction, neuroinflammation and neuronal loss → pr…
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TOPIC 064 • Neurology
Guillain–Barré Syndrome
Post-infectious immune cross-reactivity → antibodies/T cells target peripheral nerve myelin or axolemma → conducti…
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TOPIC 065 • Neurology
Myasthenia Gravis
Autoantibodies against postsynaptic AChR or associated proteins → complement-mediated receptor loss/junctional sim…
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TOPIC 066 • Neurology
Multiple Sclerosis
Autoreactive lymphocytes cross BBB → inflammatory demyelination + oligodendrocyte injury in CNS → conduction slowi…
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TOPIC 067 • Neurology / Infectious
Bacterial Meningitis
Bacterial invasion of CSF → rapid multiplication in low-opsonin environment → intense cytokine/neutrophil inflamma…
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TOPIC 068 • Neurology
Migraine
Genetically susceptible trigeminovascular system → cortical/brainstem network dysfunction ± cortical spreading dep…
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TOPIC 069 • Infectious / Critical Care
Sepsis
Dysregulated host response to infection → PAMP/DAMP recognition → cytokine/complement/coagulation activation + end…
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TOPIC 070 • Infectious / Critical Care
Septic Shock
Sepsis-induced vasoplegia + capillary leak + myocardial depression → profound distributive hypoperfusion → compens…
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TOPIC 071 • Infectious
Tuberculosis
Inhaled M. tuberculosis reaches alveoli → macrophage infection and intracellular survival → Th1 response/IFN-γ act…
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TOPIC 072 • Infectious
Malaria
Plasmodium liver stage → erythrocytic invasion and cyclic RBC rupture → fever/haemolysis; P. falciparum-infected R…
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TOPIC 073 • Infectious
Dengue and Plasma Leakage
Dengue infection → innate/antibody/T-cell immune activation → transient endothelial dysfunction + glycocalyx disru…
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TOPIC 074 • Infectious
HIV Infection and AIDS
HIV entry via CD4 + CCR5/CXCR4 → reverse transcription/integration → persistent replication in lymphoid tissue → p…
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TOPIC 075 • Immunology
Anaphylaxis
Allergen cross-links IgE on sensitised mast cells/basophils → explosive mediator release → vasodilatation + capill…
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TOPIC 076 • Rheumatology & Immunology
Systemic Lupus Erythematosus
Loss of tolerance to nuclear antigens + impaired apoptotic debris clearance → autoantibody formation → immune-comp…
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TOPIC 077 • Rheumatology & Immunology
Rheumatoid Arthritis
Genetic/environmental susceptibility → loss of tolerance to citrullinated proteins → synovial T/B-cell and macroph…
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TOPIC 078 • Rheumatology & Immunology
Gout
Chronic hyperuricaemia → monosodium urate crystal deposition → crystal phagocytosis activates NLRP3 inflammasome →…
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TOPIC 079 • Rheumatology
Osteoarthritis
Mechanical stress + ageing/genetic factors → chondrocyte dysfunction and matrix breakdown → cartilage loss → subch…
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TOPIC 080 • Endocrine / Bone
Osteoporosis
Bone resorption chronically exceeds formation → loss of trabecular connectivity + cortical thinning/porosity → red…
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TOPIC 081 • Endocrine / Bone
Vitamin D Deficiency / Osteomalacia
↓ vitamin D availability/action → ↓ intestinal Ca²⁺/phosphate absorption → secondary hyperparathyroidism → renal p…
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TOPIC 082 • Critical Care
Shock – General Pathophysiology
Failure of effective tissue perfusion → inadequate oxygen delivery/utilisation → cellular stress + anaerobic metab…
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TOPIC 083 • Critical Care
Hypovolaemic Shock
Loss of intravascular volume → ↓ venous return/preload → ↓ stroke volume/cardiac output → baroreflex tachycardia +…
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TOPIC 084 • Critical Care
Acid–Base: Metabolic Acidosis
Primary fall in HCO₃⁻ from acid gain or bicarbonate loss → ↓ pH → immediate buffering + respiratory compensation v…
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TOPIC 085 • Critical Care
Respiratory Acidosis
Alveolar hypoventilation → CO₂ retention → carbonic acid ↑ → H⁺ ↑ and pH ↓ → renal HCO₃⁻ retention/ammonium excret…
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TOPIC 086 • Critical Care
Respiratory Alkalosis
Alveolar hyperventilation beyond CO₂ production → PaCO₂ falls → carbonic acid/H⁺ falls → pH rises → renal bicarbon…
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TOPIC 087 • Critical Care
Lactic Acidosis
Lactate production exceeds clearance → lactate + associated H⁺ burden accumulates → high-anion-gap metabolic acido…
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TOPIC 088 • Electrolytes
Hyponatraemia and Cerebral Oedema
Plasma tonicity falls → water shifts into brain cells → cerebral swelling → headache, nausea, confusion, seizures;…
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TOPIC 089 • Electrolytes
Hypernatraemia
Water deficit relative to sodium → plasma hypertonicity → water exits cells → neuronal dehydration/brain shrinkage…
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TOPIC 090 • Electrolytes
Hypercalcaemia
↑ extracellular Ca²⁺ → stabilisation of excitable membranes + altered renal/GI/CNS function → weakness, constipati…
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TOPIC 091 • Electrolytes
Hypocalcaemia
↓ ionised Ca²⁺ → lower threshold for neuronal/muscle depolarisation → neuromuscular hyperexcitability → paraesthes…
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TOPIC 092 • Toxicology
Organophosphorus Poisoning
Organophosphate inhibits acetylcholinesterase → acetylcholine accumulates at muscarinic, nicotinic and CNS synapse…
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TOPIC 093 • Toxicology
Opioid Overdose
μ-opioid receptor overactivation in brainstem and CNS → reduced ventilatory response to CO₂ + depressed consciousn…
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TOPIC 094 • Toxicology
Paracetamol Toxicity
Overdose saturates glucuronidation/sulfation → more drug metabolised by CYP to NAPQI → glutathione depletion → NAP…
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TOPIC 095 • Gastroenterology & Critical Care
Acute Liver Failure
Massive hepatocyte loss → failure of detoxification, synthesis and metabolic homeostasis → coagulopathy + hyperamm…
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TOPIC 096 • Renal / Hepatology
Hepatorenal Syndrome
Advanced portal hypertension → profound splanchnic vasodilatation → ↓ effective arterial volume → intense RAAS/SNS…
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TOPIC 097 • Cardio-Renal
Cardiorenal Syndrome
Heart and kidney dysfunction reinforce each other → low forward flow + venous congestion + neurohormonal activatio…
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TOPIC 098 • Cardiopulmonary
Pulmonary Hypertension
Chronic elevation of pulmonary vascular resistance from vasoconstriction, vascular remodelling, thromboembolic obs…
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TOPIC 099 • Cardiopulmonary
Cor Pulmonale
Chronic lung/hypoxic pulmonary vascular disease → pulmonary vasoconstriction + vascular remodelling → pulmonary hy…
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TOPIC 100 • Cardiovascular / Immunology
Acute Rheumatic Fever
Group A streptococcal infection → molecular mimicry → cross-reactive antibodies/T cells against host tissues → inf…
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