Physiology

Physiology is the conceptual backbone of the entire NEET PG / INI-CET pre-clinical block. Unlike Anatomy (which rewards memory) or Biochemistry (which rewards pathways), Physiology rewards understanding of mechanism — and that is exactly why well-prepared students score heavily here while rote learners struggle. Every clinical subject downstream (Medicine, Pharmacology, Pathology, Obstetrics, Anaesthesia) is built on physiological first principles, so the marks you invest here pay compound interest across the whole paper.

This mother page gives you the full strategic map: how the subject is tested, a system-by-system high-yield breakdown matched to the official group structure (General, Nerve & Muscle, CVS, Respiratory, Renal, GIT, Endocrine, CNS, Blood), the cross-subject overlaps, recent guideline-driven shifts, a study roadmap, and a rapid-revision arsenal of tables, mnemonics and one-liners.

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How Physiology Is Tested

Weightage and exam footprint

• In NEET PG, Physiology contributes roughly 10–14 questions in a 200-question paper. It is the second or third most "concept-dense" pre-clinical subject after Pathology and Pharmacology.
• In INI-CET (AIIMS/PGI pattern), Physiology carries proportionally higher and harder weightage — frequently 6–10 questions, often integrated with applied Medicine, and presented as image/graph-based or clinical-reasoning stems.
• Physiology also "hides" inside other subjects: a Medicine question on acid–base, a Pharmacology question on receptor kinetics, or an Anaesthesia question on oxygen dissociation is physiology in disguise. Counting these, the real physiology footprint is closer to 20+ effective questions.

Recurring question styles

1. Graph / curve interpretation — oxygen–haemoglobin dissociation curve, cardiac (Wiggers, pressure–volume loop), spirometry, GFR autoregulation, action potential phases, sarcomere length–tension. These are the highest-yield format in INI-CET.
2. Value / criterion recall — normal GFR, RMP, ECG intervals, EF, anion gap, FRC, normal CSF values. Direct one-liner MCQs in NEET PG.
3. Mechanism / "which channel / which transporter" — e.g., phase 0 of cardiac AP, NKCC2 in thick ascending limb, GLUT-2 in beta cells.
4. Cause-and-effect chains — "X increases, so Y does what?" (e.g., hyperventilation → respiratory alkalosis → decreased ionised calcium → tetany).
5. Odd-one-out / assertion-reason — favoured by PGI (multiple-true-false).
6. Clinical vignette → underlying physiology — increasingly common; tests whether you can map a bedside finding to a curve or equation.

Strategic takeaway: Master curves, equations, and normal values cold. They convert directly into marks and are unambiguous, unlike conceptual debate questions.

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General Physiology

The foundation group: cell membrane, transport, body fluids, and homeostasis.

Must-know high-yield topics

• Membrane transport: Primary active (Na⁺/K⁺ ATPase — 3 Na⁺ out, 2 K⁺ in, electrogenic), secondary active (SGLT-1, NCX), facilitated diffusion (GLUT family), and channel-mediated transport.
• Na⁺/K⁺ ATPase is the single most tested transporter — inhibited by ouabain/digoxin, responsible for resting ion gradients, consumes ~25–30% of basal energy.
• Body fluid compartments: TBW ≈ 60% body weight; ICF 40%, ECF 20% (interstitial 15% + plasma 5%). "60–40–20" rule.
• Measurement (indicator dilution): TBW → tritiated water/antipyrine; ECF → inulin/mannitol; plasma → Evans blue/radioiodinated albumin. (Volume = amount/concentration.)
• Donnan equilibrium, osmolarity (calculated = 2×Na + glucose/18 + BUN/2.8), tonicity vs osmolarity.

Classic associations & traps

• Trap: Osmolarity vs osmolality vs tonicity — urea contributes to osmolarity but is an ineffective osmole (crosses membranes), so does not contribute to tonicity.
• Na⁺/K⁺ ATPase is electrogenic (net +1 charge out per cycle) — a recurring true/false point.
• Aquaporins: AQP2 is the ADH-regulated water channel in the collecting duct (links to Renal).

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Nerve & Muscle

A perennial favourite — action potentials, neuromuscular junction, and muscle mechanics generate clean, factual MCQs.

High-yield topics

• Resting membrane potential (RMP): Nerve ≈ −70 mV, skeletal muscle ≈ −90 mV, cardiac ventricle ≈ −90 mV, SA node ≈ −55 to −60 mV (unstable). Set mainly by K⁺ (Goldman equation; K⁺ permeability dominates at rest).
• Action potential phases: Depolarisation = voltage-gated Na⁺ influx; repolarisation = K⁺ efflux; absolute vs relative refractory period (Na⁺ channel inactivation gates).
• Nerve fibre classification (Erlanger–Gasser & numerical): A-alpha fastest (proprioception, motor); C fibres slowest, unmyelinated (slow pain, postganglionic autonomic). Susceptibility to local anaesthetics: small myelinated B/Aδ blocked first; to hypoxia: large fibres first; to pressure: large fibres first.
• Neuromuscular junction: ACh → nicotinic (Nm) receptors → end-plate potential. Myasthenia gravis = antibodies to postsynaptic ACh receptors; Lambert–Eaton = antibodies to presynaptic voltage-gated Ca²⁺ channels (improves with repetition).
• Excitation–contraction coupling: T-tubule depolarisation → DHP receptor (voltage sensor) → ryanodine receptor → Ca²⁺ release from SR → troponin C → cross-bridge cycling. Skeletal muscle does NOT need extracellular Ca²⁺ for contraction; cardiac muscle DOES (calcium-induced calcium release).
• Length–tension relationship: Maximum active tension at optimal sarcomere length (~2.0–2.2 μm) where actin–myosin overlap is ideal.

Muscle types comparison

Feature	Skeletal	Cardiac	Smooth
Striations	Yes	Yes	No
Control	Voluntary	Involuntary	Involuntary
Ca²⁺ source	SR (T-tubule triad)	SR + extracellular (CICR)	Extracellular + SR
Ca²⁺ binds	Troponin C	Troponin C	Calmodulin → MLCK
Pacemaker/auto	No	Yes (SA node)	Some (single-unit)
Syncytium	No	Functional syncytium	Single-unit type

Traps

• Tetanus impossible in cardiac muscle due to long refractory period (protective) — high yield.
• Latch bridge mechanism (smooth muscle) sustains tension with low ATP use.
• "Fast" twitch (Type II) = glycolytic, white, fatigues fast; "slow" (Type I) = oxidative, red, fatigue-resistant.

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Cardiovascular System (CVS)

The single highest-yield physiology system for NEET PG/INI-CET, dense with curves and numbers.

High-yield topics

• Cardiac action potentials:
  • Ventricular (fast response): Phase 0 = Na⁺ in; Phase 1 = transient K⁺ out + Cl⁻; Phase 2 (plateau) = Ca²⁺ in (L-type) balanced by K⁺ out; Phase 3 = K⁺ out; Phase 4 = resting.
  • SA node (slow response): No true resting potential; Phase 4 slow depolarisation via funny current (If, Na⁺); Phase 0 via Ca²⁺ (L-type). Determines automaticity.
• Conduction velocity order: Purkinje fibres fastest → atrial/ventricular muscle → AV node slowest (allows atrial kick). Mnemonic: "Park At Venture AV" — Purkinje > Atria > Ventricle > AV node.
• Cardiac cycle / Wiggers diagram: Sequence of pressure, volume, ECG, and heart sounds. S1 = AV valve closure (start of systole); S2 = semilunar closure. Isovolumetric contraction/relaxation phases (all valves closed).
• Pressure–volume loop: EDV ~120 mL, ESV ~50 mL, SV ~70 mL, EF = SV/EDV ≈ 60–65% (normal ≥55%). Width = stroke volume; area = stroke work.
• Frank–Starling law: Increased venous return (preload) → increased force of contraction. Afterload = aortic/arterial resistance.
• Cardiac output = HR × SV; Fick principle: CO = O₂ consumption / (arterial − venous O₂ content).
• Baroreceptor reflex: Carotid sinus (CN IX) and aortic arch (CN X) → NTS → buffers acute BP changes. Increased BP → increased firing → decreased sympathetic, increased vagal → bradycardia.
• ECG intervals: PR 0.12–0.20 s; QRS <0.12 s; QT corrected (Bazett) ~0.44 s. P = atrial depolarisation; QRS = ventricular depolarisation (atrial repol hidden); T = ventricular repolarisation.

Pressure values to memorise

Chamber/Vessel	Pressure (mmHg)
Right atrium (CVP)	0–8
Right ventricle	25/0–8
Pulmonary artery	25/10 (mean ~15)
PCWP (≈ LA)	6–12
Left atrium	2–12
Left ventricle	120/0–10
Aorta	120/80

Traps

• Coronary blood flow is maximal in diastole (especially left ventricle, which is compressed during systole) — a classic. Subendocardium is most vulnerable to ischaemia.
• The plateau phase (Ca²⁺ influx) is the longest and is the basis of the long refractory period.
• Pulse pressure (SBP − DBP) rises with decreased arterial compliance (elderly, atherosclerosis) and increased SV.
• A-V O₂ difference is greatest in cardiac muscle (highest extraction).

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Respiratory System

Graph-heavy and equation-heavy — reliably yields 1–3 questions.

High-yield topics

• Lung volumes & capacities:
  • TV ~500 mL; IRV ~3000; ERV ~1100; RV ~1200.
  • FRC = ERV + RV (~2300 mL) — cannot be measured by spirometry; need helium dilution/body plethysmography/N₂ washout.
  • VC = IRV + TV + ERV; TLC = VC + RV.
• Compliance: C = ΔV/ΔP. Increased in emphysema (loss of elastic recoil); decreased in fibrosis, ARDS, oedema. Hysteresis on inflation/deflation due to surfactant.
• Surfactant: Dipalmitoylphosphatidylcholine (lecithin) from type II pneumocytes; reduces surface tension, prevents alveolar collapse, increases compliance. L:S ratio ≥2 = lung maturity (links to Obstetrics/NRDS).
• Oxygen–haemoglobin dissociation curve: Sigmoid. P50 ~27 mmHg.
  • Right shift (decreased affinity, easier O₂ unloading): increased CO₂, H⁺ (low pH), temperature, 2,3-BPG (Bohr effect).
  • Left shift: opposite + fetal Hb, CO, methaemoglobin.
• CO₂ transport: ~70% as bicarbonate (chloride/Hamburger shift), ~23% carbamino, ~7% dissolved. Haldane effect = deoxygenated blood carries more CO₂.
• V/Q ratio: ~0.8 overall. Apex: high V/Q (dead space-like); base: low V/Q (shunt-like). Zone 1 (apex) PA > Pa > Pv; Zone 3 (base) Pa > Pv > PA.
• Control of breathing: Central chemoreceptors (medulla, respond to CSF H⁺/CO₂ — the main drive); peripheral (carotid/aortic bodies, respond to PaO₂ <60). Dorsal (inspiration) & ventral respiratory groups; pre-Bötzinger complex = rhythm generator.

Traps

• Hypoxic pulmonary vasoconstriction is the opposite of systemic circulation (where hypoxia causes vasodilation) — diverts blood to better-ventilated alveoli.
• The major stimulus to normal respiration is PaCO₂ via central chemoreceptors, NOT PaO₂. Hypoxic drive matters only in chronic CO₂ retainers.
• FRC is the volume at which inward elastic recoil = outward chest wall recoil.
• Most O₂ in blood is bound to Hb, not dissolved; PaO₂ reflects dissolved O₂ only.

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Renal System

Equation-rich and integration-heavy; closely tied to acid–base and endocrine.

High-yield topics

• GFR: Normal ~125 mL/min (180 L/day). Measured by inulin clearance (gold standard; freely filtered, neither secreted nor reabsorbed). Creatinine clearance overestimates GFR slightly (some tubular secretion). PAH clearance estimates renal plasma flow (RPF ~625 mL/min); filtration fraction = GFR/RPF ≈ 20%.
• Autoregulation of GFR/RBF (MAP 80–180 mmHg): myogenic mechanism + tubuloglomerular feedback (macula densa senses NaCl via NKCC2 → adenosine → afferent constriction).
• Tubular transport map:
  • PCT: ~65% reabsorption (Na⁺, glucose via SGLT-2, amino acids, HCO₃⁻); site of glucose threshold (~180–200 mg/dL) and Tm.
  • Thick ascending limb: NKCC2 (loop diuretic target); impermeable to water; generates dilution.
  • DCT: NCC (thiazide target); Ca²⁺ reabsorption (PTH).
  • Collecting duct: principal cells ENaC (aldosterone), AQP2 (ADH); intercalated cells (acid–base).
• Countercurrent multiplier (loop of Henle) and exchanger (vasa recta) generate the medullary osmotic gradient (up to ~1200 mOsm/L) for urine concentration. Urea recycling contributes.
• RAAS: Renin (JG cells) → angiotensin I → ACE (lung) → AT-II → vasoconstriction + aldosterone + ADH + thirst. AT-II preferentially constricts the efferent arteriole (maintains GFR — basis of ACEi effect in renal artery stenosis).
• Acid–base: Henderson–Hasselbalch (pH = 6.1 + log[HCO₃⁻]/0.03×PaCO₂); anion gap = Na⁺ − (Cl⁻ + HCO₃⁻) ≈ 8–12. HAGMA mnemonic MUDPILES.

Clearance & values table

Parameter	Normal value
GFR	~125 mL/min
RPF (PAH)	~625 mL/min
RBF	~1100 mL/min (~20% CO)
Filtration fraction	~20%
Glucose Tm	~375 mg/min
Renal threshold (glucose)	~180–200 mg/dL

Traps

• Inulin = GFR marker; PAH = RPF marker. Don't swap.
• ADH acts on V2 receptors (collecting duct, AQP2 — antidiuresis) and V1 (vasoconstriction).
• Hyperkalaemia of distal RTA vs hypokalaemia of proximal/classic distal RTA — classic INI-CET trap.
• ACEi → efferent dilation → decreased intraglomerular pressure → renoprotective but can ↑ creatinine acutely.

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Gastrointestinal Tract (GIT)

Often underprepared, but secretions, hormones, and motility yield direct MCQs.

High-yield topics

• GI hormones:

Hormone	Source	Main action	Stimulus
Gastrin	G cells (antrum)	↑ HCl (via ECL/histamine)	Peptides, vagus (GRP)
CCK	I cells (duodenum)	Gallbladder contraction, pancreatic enzymes, satiety	Fat, amino acids
Secretin	S cells (duodenum)	Pancreatic/biliary HCO₃⁻; ↓ gastric acid	Acid (H⁺)
GIP	K cells	Insulin release (incretin); ↓ acid	Glucose, fat
Motilin	M cells	MMC (interdigestive motility)	Fasting
Somatostatin	D cells	Universal inhibitor	Acid

• Gastric acid secretion: Parietal cell H⁺/K⁺ ATPase (proton pump). Three phases: cephalic (vagal), gastric, intestinal. Stimulated by gastrin, histamine (H2), ACh (M3); inhibited by somatostatin, secretin, prostaglandins.
• Incretin effect: Oral glucose evokes more insulin than IV glucose (GIP + GLP-1) — basis of DPP-4 inhibitors/GLP-1 agonists (Pharmacology overlap).
• Pancreatic secretion: Enzymes (acinar) + HCO₃⁻ (ductal, secretin-driven). Trypsinogen → trypsin (enterokinase) activates other zymogens.
• Bile & enterohepatic circulation: Bile salts reabsorbed in terminal ileum (links to B12, ileal resection).
• Absorption sites: Iron & folate — duodenum/jejunum; B12 — terminal ileum (needs intrinsic factor); fat-soluble vitamins need bile.

Traps

• Migrating motor complex (MMC) is driven by motilin during fasting ("housekeeper"). Erythromycin is a motilin agonist (prokinetic).
• Secretin's net effect on gastric acid is inhibitory (despite "secret-in" sounding stimulatory).
• Intrinsic factor from parietal cells (not chief cells) is essential for B12 — pernicious anaemia link.

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Endocrine System

Conceptually dense; reliably tested with feedback loops and receptor mechanisms.

High-yield topics

• Hormone signalling classes:
  • cAMP (Gs): ACTH, TSH, FSH, LH, glucagon, PTH, ADH (V2), calcitonin, βreceptors.
  • cGMP: ANP, NO.
  • IP3/DAG/Ca²⁺ (Gq): GnRH, TRH, GHRH, ADH (V1), oxytocin, angiotensin II, α1.
  • Tyrosine kinase: insulin, IGF-1, growth factors.
  • Intracellular/nuclear receptors: steroids, thyroid hormone, vitamin D, retinoids.
• Thyroid: T4 is the main secreted form; T3 is more active (peripheral deiodination by 5'-deiodinase). Reverse T3 inactive. Wolff–Chaikoff (excess iodide suppresses) vs Jod–Basedow (iodine-induced hyperthyroidism).
• Insulin: Secreted by beta cells; glucose enters via GLUT-2, metabolised → ATP → closes K⁺ ATP channel → depolarisation → Ca²⁺ influx → exocytosis (sulfonylurea target). GLUT-4 = insulin-dependent (muscle/adipose).
• Calcium homeostasis: PTH (↑ Ca²⁺: bone resorption, renal Ca²⁺ reabsorption + phosphate excretion, activates 1-α-hydroxylase → calcitriol). Vitamin D ↑ gut Ca²⁺ & PO₄³⁻ absorption. Calcitonin ↓ Ca²⁺.
• Adrenal: Cortex zones — GFR = Glomerulosa (aldosterone), Fasciculata (cortisol), Reticularis (androgens). "Salt, Sugar, Sex — deeper you go, sweeter it gets."
• GH: Acts directly + via IGF-1; diabetogenic; pulsatile, peaks in deep sleep. GHRH ↑, somatostatin ↓.

Traps

• T3 is more potent but T4 is more abundant. Most circulating T3 is from peripheral conversion.
• ADH uses both V1 (Gq) and V2 (Gs) — a favourite tricky point.
• Posterior pituitary hormones (ADH, oxytocin) are synthesised in hypothalamus (supraoptic/paraventricular) and merely stored/released by posterior pituitary.
• Insulin lowers serum K⁺ (drives it intracellularly) — therapeutic in hyperkalaemia.

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Central Nervous System (CNS)

Tests sensory/motor pathways, special senses, sleep, and synaptic transmission.

High-yield topics

• Sensory tracts:
  • Dorsal column–medial lemniscus: Fine touch, vibration, proprioception. Crosses in medulla. (DCML — "fine" sensations.)
  • Spinothalamic: Pain & temperature. Crosses at the level (within 1–2 segments) in the spinal cord. Explains Brown-Séquard dissociation.
• Motor: Corticospinal (pyramidal) tract crosses at pyramidal decussation. UMN vs LMN lesion signs (hyper- vs hyporeflexia, Babinski).
• Cerebellum: Coordination, balance; lesions → ipsilateral signs, intention tremor, ataxia, dysdiadochokinesia.
• Basal ganglia: Direct (D1, facilitatory) vs indirect (D2, inhibitory) pathways; dopamine from SNc. Links to Parkinson's/Huntington's.
• Synaptic transmitters: Glutamate (main excitatory), GABA/glycine (main inhibitory). NMDA receptor (Ca²⁺, Mg²⁺ block, learning/LTP).
• CSF: Produced by choroid plexus (~500 mL/day; total ~150 mL); normal pressure 70–180 mm H₂O; protein 15–45 mg/dL; glucose 2/3 of plasma.
• Sleep: REM = desynchronised (paradoxical) EEG, dreaming, atonia, increased ACh. NREM stage 3–4 = slow-wave delta. Reticular activating system maintains wakefulness.
• Special senses: Rods (rhodopsin, scotopic, more sensitive) vs cones (photopic, colour, fovea). Hair cells (cochlea, tonotopic — base = high frequency).

Traps

• DCML crosses in the medulla; spinothalamic crosses at the cord level — basis of dissociated sensory loss.
• Resting/wakefulness: ACh high in REM; serotonin/noradrenaline minimal in REM.
• CSF glucose low in bacterial meningitis (overlap with Microbiology/Medicine).

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Blood

Short but consistently tested — haemostasis, Hb, groups, and immunity basics.

High-yield topics

• Haematopoiesis: Fetal — yolk sac → liver/spleen → bone marrow. EPO from renal peritubular interstitial cells (hypoxia stimulus, HIF pathway).
• Haemoglobin: Adult HbA (α2β2), HbA2 (α2δ2), HbF (α2γ2 — higher O₂ affinity, left-shifted). Methaemoglobin (Fe³⁺) cannot carry O₂.
• Haemostasis:
  • Primary = platelet plug (vWF, GpIb adhesion, GpIIb/IIIa aggregation).
  • Secondary = coagulation cascade. Intrinsic (aPTT), extrinsic (PT/INR — factor VII, shortest half-life), common pathway. Factor II, VII, IX, X + protein C/S are vitamin K–dependent.
  • Fibrinolysis: plasminogen → plasmin (tPA).
• Blood groups: ABO (anti-A/anti-B IgM, preformed), Rh (anti-D IgG, crosses placenta → haemolytic disease of newborn). "O" universal donor (RBC), "AB" universal recipient.

Coagulation test interpretation

Test	Pathway	Prolonged in
PT/INR	Extrinsic + common	Warfarin, VII deficiency, liver disease
aPTT	Intrinsic + common	Heparin, haemophilia A/B, vWD
Thrombin time	Fibrinogen→fibrin	Heparin, DIC, dysfibrinogenaemia
Bleeding time	Platelet/vessel	Thrombocytopenia, vWD, aspirin

Traps

• Factor VII has the shortest half-life → PT/INR rises first in early warfarin/liver failure.
• vWF deficiency prolongs aPTT (carries factor VIII) AND affects platelet function (prolonged BT) — a dual hit.
• EPO source is the kidney (interstitial cells), not the marrow — basis of anaemia of CKD.

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Cross-Subject Integration Points

Physiology rarely stands alone in modern papers. Know these overlaps:

• Physiology ↔ Pharmacology: Receptor signalling (Gs/Gq/Gi), proton pump (PPIs), NKCC2/NCC/ENaC (diuretics), SGLT-2 (gliflozins), incretins (DPP-4i/GLP-1), beta-blockers and the funny current (ivabradine on If).
• Physiology ↔ Pathology: Anaemia of CKD (EPO), pernicious anaemia (IF), heart failure (Frank–Starling, EF), RTA.
• Physiology ↔ Medicine: Acid–base disorders, oxygen dissociation in critical care, ECG, autonomic dysreflexia.
• Physiology ↔ Obstetrics: Surfactant/L:S ratio (NRDS), fetal Hb, fetal circulation shunts (ductus venosus/arteriosus, foramen ovale).
• Physiology ↔ Anaesthesia: FRC, closing capacity, oxygen cascade, MAC concepts, neuromuscular junction (NMJ blockers).
• Physiology ↔ Biochemistry: 2,3-BPG, vitamin K–dependent factors, calcitriol synthesis, deiodinase.

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Recent Update Themes & Guideline Shifts

• SGLT-2 / incretin physiology is increasingly examined because of the explosion of gliflozins and GLP-1 agonists in clinical practice — expect questions linking renal glucose handling and the incretin effect.
• HIF–EPO axis features in newer questions (HIF-PH inhibitors / roxadustat for CKD anaemia) — know that EPO is oxygen-sensed via HIF stabilisation.
• Funny current (If) and ivabradine — SA node pacemaker physiology now has a direct drug tie-in.
• Acid–base & critical-care physiology has gained prominence post-pandemic (ARDS, V/Q, hypoxic pulmonary vasoconstriction, oxygen cascade).
• Microbiome and gut–brain axis appears as newer conceptual stems in INI-CET.
• The NMC Competency-Based Medical Education (CBME) curriculum emphasises applied/integrated physiology, nudging examiners toward clinical-vignette and graph-based stems rather than pure recall.

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Study Roadmap

Phase 1 — Foundation (concept building)

1. Start with General → Nerve & Muscle: these underlie everything (channels, AP, transport).
2. Move to CVS → Respiratory → Renal as a block — they share the most curves, equations, and acid–base/integration logic. This is your highest-yield cluster; spend the most time here.
3. Then Endocrine → GIT → CNS → Blood.

Phase 2 — Consolidation

• For each system, build a one-page sheet of: curves, normal values, transporters/channels, and the 3–4 classic traps.
• Solve previous-year NEET PG + INI-CET questions topic-wise immediately after each system. Physiology PYQs repeat themes heavily.
• Convert every graph into a self-drawn version — you must be able to redraw the OHDC, Wiggers, PV loop, spirometry, and GFR autoregulation from memory.

Phase 3 — Integration

• Do mixed grand tests; tag every wrong physiology question to its system sheet.
• Practise mapping vignettes → curves/equations (the INI-CET skill).

Last-week revision strategy

• Do NOT read new theory. Revise only your one-page system sheets and high-yield tables.
• Drill the values tables (pressures, GFR/RPF, lung volumes, ECG intervals, normal CSF) — these are free marks.
• Re-draw the five core curves daily.
• Run through the rapid-fire one-liners below the night before.
• Revisit the cross-subject overlap list — physiology answers often unlock pharmacology/medicine questions.

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High-Yield Mnemonics

• Vitamin K–dependent factors: "1972" → II, VII, IX, X (+ protein C & S).
• Adrenal cortex zones: "GFR — Salt, Sugar, Sex" (Glomerulosa-aldosterone, Fasciculata-cortisol, Reticularis-androgens).
• HAGMA causes: MUDPILES (Methanol, Uraemia, DKA, Propylene glycol/Paraldehyde, Iron/INH, Lactic acidosis, Ethylene glycol, Salicylates).
• Right shift of OHDC: "CADET, face Right" — CO₂, Acid, 2,3-DPG, Exercise, Temperature ↑.
• Conduction velocity (fastest→slowest): Purkinje > Atria/Ventricle > AV node ("Park Ahead, Very slow At AV").
• Vit-K factors & extrinsic: Factor VII = lucky 7, shortest half-life, monitored by PT.

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Rapid-Fire One-Liners

1. Inulin measures GFR; PAH measures renal plasma flow; creatinine slightly overestimates GFR.
2. Coronary (left ventricular) perfusion occurs mainly in diastole.
3. Cardiac muscle cannot be tetanised due to its long refractory (plateau, Ca²⁺) phase.
4. Resting membrane potential is set chiefly by K⁺ permeability (Goldman/Nernst).
5. Factor VII has the shortest half-life — PT/INR is the earliest to rise in warfarin/liver failure.
6. Surfactant is dipalmitoyl-phosphatidylcholine from type II pneumocytes; L:S ratio ≥2 = mature lungs.
7. Major respiratory drive = PaCO₂ acting on central chemoreceptors (CSF H⁺).
8. Skeletal muscle contraction needs SR Ca²⁺ only; cardiac muscle needs extracellular Ca²⁺ (CICR).
9. EPO is produced by renal peritubular interstitial cells under hypoxia (HIF pathway).
10. T4 is most abundant, T3 is most active (peripheral 5'-deiodinase); reverse T3 is inactive.
11. Hypoxic pulmonary vasoconstriction diverts blood from poorly ventilated alveoli (opposite of systemic vessels).
12. ADH acts via V2 (aquaporin-2, antidiuresis) and V1 (vasoconstriction) receptors.
13. B12 is absorbed in the terminal ileum and requires parietal-cell intrinsic factor.
14. Normal ejection fraction ≥55% (EF = SV/EDV).