🧬 NEET BIOLOGY – HUMAN HEART (COMPLETE REVISION POST)
❤️ Human Heart – Structure, Function & NEET Facts
📍 Location & Covering
• Located in the thoracic cavity, between the lungs
• Slightly tilted to the left side
• Covered by a double-layered membrane called Pericardium
• Pericardial fluid reduces friction during heartbeat
📍 Structure of Heart
✔ Four chambers:
• Right Atrium (RA)
• Right Ventricle (RV)
• Left Atrium (LA)
• Left Ventricle (LV)
✔ Septa:
• Inter-atrial septum → separates atria
• Inter-ventricular septum → separates ventricles
✔ Left ventricle has the thickest wall
(Reason: pumps blood to entire body)
📍 Valves of Heart (VERY IMPORTANT FOR NEET)
🔹 Tricuspid Valve
• Between Right Atrium & Right Ventricle
🔹 Bicuspid / Mitral Valve
• Between Left Atrium & Left Ventricle
🔹 Semilunar Valves
• Pulmonary semilunar valve
• Aortic semilunar valve
📌 Function of valves:
→ Prevent backflow of blood
📍 Blood Circulation Pathway
1️⃣ Deoxygenated blood → Right Atrium
2️⃣ RA → RV (through tricuspid valve)
3️⃣ RV → Pulmonary artery → Lungs
4️⃣ Oxygenated blood → Left Atrium
5️⃣ LA → LV (through bicuspid valve)
6️⃣ LV → Aorta → Whole body
💡 NEET Tip:
Pulmonary artery carries deoxygenated blood
Pulmonary vein carries oxygenated blood
📍 Cardiac Cycle
• One complete heartbeat = 0.8 sec
• Atrial systole – 0.1 sec
• Ventricular systole – 0.3 sec
• Joint diastole – 0.4 sec
📍 Heartbeat Control (Myogenic Heart)
• Heart initiates impulse on its own
• SA node → Natural pacemaker
• AV node → Bundle of His → Purkinje fibers
📌 Normal heart rate:
• Adult: 72 beats/min
📍 Heart Sounds
🔊 Lub → closure of AV valves
🔊 Dub → closure of semilunar valves
📍 NEET PYQs & One-Liners
✔ Thickest chamber → Left ventricle
✔ Pacemaker of heart → SA node
✔ Valve between LA & LV → Bicuspid valve
✔ Heart muscle → Cardiac muscle (striated + involuntary)
✔ Blood supply of heart → Coronary arteries
🔥 NEET EXAM STRATEGY
✅ Draw heart diagram daily
✅ Learn valve positions clearly
✅ Revise circulation pathway before exam
✅ Expect 2–3 direct questions from this topic
✨ Consistency + Revision = NEET Selection
📖 Study daily. Trust the process. Keep pushing.
