Pattern 1: Pacemaker Identification (NEET 2019, 2021, 2023)

• What is asked: Which node initiates the heartbeat? Which structure sets cardiac rhythm?
• Correct answer: Always SAN (sinoatrial node)
• Common trap: AVN — because students know it's important and "in the AV region"
• Key fact: SAN fires at 70-75 bpm; AVN fires at 40-60 bpm (backup only)
• How to guarantee correct answer: Memorize "SAN = pacemaker" as an absolute rule; AVN = delay + relay

Pattern 2: Pulmonary Artery Blood Type (NEET 2018, 2020, 2022)

• What is asked: What type of blood does the pulmonary artery carry? Which statement about pulmonary vessels is correct?
• Correct answer: Pulmonary artery = deoxygenated (from RV to lungs); Pulmonary vein = oxygenated (from lungs to LA)
• Common trap: Assuming "artery = oxygenated" applies universally
• Key fact: The pulmonary artery is the only artery that carries deoxygenated blood; pulmonary veins are the only veins carrying oxygenated blood
• How to guarantee correct answer: Think about function and direction, not just vessel type name

Pattern 3: ECG Wave Interpretation (NEET 2020, 2024)

• What is asked: What does the QRS complex represent? What is hidden within the QRS complex?
• Correct answer: QRS = ventricular DEPOLARIZATION; atrial repolarization is hidden within QRS
• Common trap: QRS = ventricular contraction (confusing electrical with mechanical event)
• Key fact: ECG records ONLY electrical events; mechanical events $\frac{contraction}{relaxation}$ follow the electrical triggers
• How to guarantee correct answer: Always say "depolarization" not "contraction" when referring to QRS; "repolarization" not "relaxation" for T wave

Pattern 4: Blood Group Universality (Multiple years)

• What is asked: Who is the universal donor/recipient?
• Correct answer: O-negative = universal donor; AB-positive = universal recipient
• Common trap: Confusing donor and recipient; forgetting that Rh factor matters for "true" universal roles
• Key fact: O has no RBC antigens (nothing to be rejected); AB has no plasma antibodies (cannot reject anyone)

Pattern 5: Cardiac Cycle Timing (NEET 2017, 2019, 2022)

• What is asked: Duration of individual phases; total cardiac cycle; which phase is longest
• Correct answer: Atrial systole 0.1 s; Ventricular systole 0.3 s; Joint diastole 0.4 s (longest); Total 0.8 s
• Common trap: Thinking ventricular systole is longest (it is not; diastole is)
• Exam tip: Memorize 0.1 + 0.3 + 0.4 = 0.8 s as a fixed formula

Frequency Analysis Table