Conduction of the Cardiac System

Introduction

• Presenter: Dr. Mike
• Topic: Conduction of the cardiac system (electrical current in the heart)
• Importance: Tells heart muscle (myocardium) to contract

Key Concepts

Heart Muscle Characteristics

• Specialized muscle
• Under a microscope, muscle cells are connected with small gaps
• At rest, cells have a negative charge
• Depolarization: Change from negative to positive charge
  • Essential for muscle contraction

Depolarization

• Process:
  • Cells must change from a negative to a positive charge to contract
  • This change spreads easily from one cell to another
• Importance: Muscles won’t contract without depolarization

Cardiac Conduction System

Sinoatrial Node (SA Node)

• Location: Atria of the heart
• Function: Pacemaker of the heart
  • Sets sinus rhythm
  • Normal rate: 60 to 100 beats per minute
• Charge Behavior:
  • At rest, negatively charged
  • Spontaneously becomes positive
  • Sends wave of positive charge through atrial muscle

Atrial Muscle Charge Propagation

• Positive charge spreads through atrial muscle
  • From SA node, charge moves throughout atria
  • Ensures coordinated contraction of atrial muscle

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