The Basics of the Heart: Structure, Function, and Health Tips

BASICS OF THE HEART

• Location: Fist-sized, in the middle mediastinum, tilted left.
• Apex: Formed by left ventricle (LV), felt in 4th or 5th intercostal space.
• Weight: ~320g (males), ~270g (females).

Mnemonic: Heart Anatomy is "LEFT"

• Location – Middle mediastinum
• Extension – Obliquely placed
• Four chambers – RA, RV, LA, LV
• Tip (Apex) – Left ventricle

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HEART CHAMBERS

1. Right Atrium (RA) – Receives deoxygenated blood from SVC, IVC. Contains SA node.
2. Right Ventricle (RV) – Pumps to lungs via pulmonary artery.
3. Left Atrium (LA) – Receives oxygenated blood from pulmonary veins.
4. Left Ventricle (LV) – Pumps to body via aorta.

Mnemonic: Blood Flow Pathway - "RA-RV-PA-LA-LV-A"

• RA → RV → Pulmonary Artery → Lungs → LA → LV → Aorta → Body

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HEART VALVES

• AV Valves:
• Right side: Tricuspid (3 leaflets)
• Left side: Mitral (2 leaflets)
• Semilunar Valves:
• Pulmonary Valve (RV → Pulmonary artery)
• Aortic Valve (LV → Aorta)

Mnemonic: "Try Pulling My Aorta" (for valve locations)

• Tricuspid
• Pulmonary
• Mitral
• Aortic

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CONDUCTION SYSTEM

1. SA Node (Pacemaker) – Starts impulse.
2. AV Node – Delays impulse.
3. Bundle of His – Conducts to ventricles.
4. Purkinje Fibers – Distributes impulse.

Mnemonic: "SABP" - Super Athletes Build Power

• SA Node
• AV Node
• Bundle of His
• Purkinje Fibers

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CORONARY ARTERIES

• Left Coronary Artery (LCA) → LAD & Circumflex (supplies LV, septum).
• Right Coronary Artery (RCA) → Supplies RA, RV, SA, AV nodes.

Mnemonic: "Left LAD Circles, Right Runs Solo"

• Left Coronary → LAD & Circumflex
• Right Coronary → SA, AV nodes

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CARDIAC CYCLE (Phases)

1. Isovolumic Contraction → S1 sound (Mitral & Tricuspid close).
2. Ejection Phase → Blood pushed to Aorta & Pulmonary artery.
3. Isovolumic Relaxation → S2 sound (Aortic & Pulmonary close).
4. Filling Phase → Ventricles fill with blood.

Mnemonic: "I Eat In Fast"

• Isovolumic Contraction
• Ejection
• Isovolumic Relaxation
• Filling

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PHYSIOLOGY: CARDIAC OUTPUT (CO)

CO = Heart Rate (HR) × Stroke Volume (SV)

• Preload – Blood returning to heart.
• Afterload – Resistance heart pumps against.
• Contractility – Strength of contraction.

Mnemonic: "P.A.C."

• Preload
• Afterload
• Contractility

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BLOOD PRESSURE REGULATION

• BP = CO × TPR (Total Peripheral Resistance)
• Sympathetic – Increases HR & BP.
• Parasympathetic – Decreases HR & BP.

Mnemonic: "S.I.P." (for BP factors)

• Sympathetic
• Increase CO
• Pressure Regulation