Understanding Cardiac Electrophysiology

This video tutorial covers cardiac electrophysiology, focusing on the electrical processes within the heart. It explains gap junctions, ion movement, and the phases of cardiac action potentials. The tutorial also discusses the role of the SA node, depolarization, repolarization, and the sodium-potassium pump, providing a foundation for understanding EKG interpretation.

What is the primary function of gap junctions in cardiac cells?

• To produce hormones

• To store energy

• To allow the movement of ions between cells

• To provide structural support

Which node is responsible for generating the action potential in a normal heart?

• AV node

• Purkinje fibers

• SA node

• Bundle of His

What is the initial voltage of the ventricular myocyte membrane action potential?

• 0 millivolts

• 20 millivolts

• -70 millivolts

• -90 millivolts

During which phase does sodium rapidly enter the cell, causing depolarization?

• Phase 1

• Phase 3

• Phase 2

• Phase 0

Which ion is primarily responsible for the rapid upstroke in the action potential?

• Chloride

• Potassium

• Calcium

• Sodium

What is the main effect of sodium channel blockers on cardiac cells?

• They slow down depolarization

• They increase calcium influx

• They enhance depolarization

• They block potassium efflux

What occurs during the plateau phase of the action potential?

• The cell remains at rest

• Calcium enters while potassium exits the cell

• Only potassium exits the cell

• Only sodium enters the cell

What is the role of the sodium-potassium pump in cardiac cells?

• To increase calcium levels

• To initiate depolarization

• To maintain the resting membrane potential

• To block ion channels

What happens to calcium channels during phase three of the action potential?

• They become more permeable

• They remain unchanged

• They close

• They open

Which phase is characterized by a balance of inward and outward ion currents?

• Phase 3

• Phase 1

• Phase 2

• Phase 0