Physiologic Properties of the Heart

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Physiologic Properties of the Heart by Mind Map: Physiologic Properties of the Heart

1. Autorhytmicity (Chronotropism)

1.1. Self-Excitation

1.2. Contributors:

1.2.1. AV node

1.2.2. SA node AP in SA node Phase 0 Phase 3 Phase 4 ** Phase 1 and 2 are absent in nodal action

1.2.3. His Purkinje system

2. Conductivity (Dromotropism)

2.1. AP propagated within the cardiac tissue

2.2. SA Node

2.2.1. Location Superior posterolateral wall of the Right atrium

2.2.2. Almost no contractile muscle filaments

2.2.3. serves as the PIMARY PACE MAKER

2.2.4. Over Ride Suppression Inhibits Latent Pacemakers AV node Bundle of His Purkinje Fiber

2.2.5. Ectopic Pacemakers Latent pacemakers will drive the heart if SA is suppressed Faster Latent > SA node SA node conduction is blocked

2.3. AV node

2.3.1. Area of Conducting delay

2.3.2. Cause of Slow Conduction

2.3.3. Location Posterior Wall of the Right Atrium Behind tricuspid valve

2.4. Bundle of His

2.4.1. Latent pacemaker

2.4.2. Fast Caused by high level of permeability of the gab junctions at intercalated discs

3. Contractility (Inotropism)

3.1. Frank sterling mechanism

3.1.1. Increase stretch = increase blood contraction Increase Pump

3.2. Phase 0

3.2.1. Depolarization

3.2.2. Fast Sodium Channel Close

3.3. Phase 2

3.3.1. Calcium channel open

3.3.2. Fast K close

3.4. Phase 3

3.4.1. Rapid repolarization

3.4.2. Ca Close

3.4.3. Slow K open

3.5. Phase 4

3.5.1. Resting Membrane Potential

4. Excitability (Bathmotropism)

4.1. Excitation-Contraction Coupling Mechanism

4.2. Action Potential Travels to the T tubules

4.2.1. L type Calcium Channel at T t ubule

4.2.2. Release of Calcium from Sarcoplasmic Reticulum to the Cytoplasm Calcium Ions will Act on myofibrils Causes Contaction