Cardiac Cells
What are the two main types of cardiac cells?
Myocardial cells and pacemaker cells.
What does an EKG measure?
The electrical activity of the heart.
What occurs during phase 0 of the cardiac action potential?
Rapid depolarization occurs as sodium channels open.
Name one key electrolyte involved in cardiac action potential.
Sodium (Na+), potassium (K+), calcium (Ca++), or magnesium (Mg++).
What is the primary pacemaker of the heart?
The sinoatrial (SA) node.
What is the primary function of pacemaker cells?
To generate and conduct electrical impulses.
What does the P wave represent?
Atrial depolarization.
What is depolarization?
The process by which the inside of the cell becomes less negative.
What role does sodium play in depolarization?
Sodium influx causes the cell to become positively charged.
Describe the pathway of electrical conduction from the SA node.
The impulse travels from the SA node through the atria to the AV node, then to the Bundle of His and Purkinje fibers.
Name one property of cardiac cells.
Automaticity, excitability, conductivity, or contractility.
What does the QRS complex indicate?
Ventricular depolarization.
Describe the role of calcium during the plateau phase.
Calcium influx maintains depolarization and prolongs the action potential.
How do potassium ions affect repolarization?
Potassium ions exit the cell, helping to restore the negative charge.
What is the role of the AV node?
It slows down the electrical impulse to allow the atria to contract before the ventricles.
Explain automaticity in cardiac cells.
The ability of pacemaker cells to initiate an electrical impulse without external stimulation.
What does the T wave represent?
Ventricular repolarization.
What happens during phase 3?
Repolarization occurs as potassium exits the cell, returning the cell to a negative charge.
Explain the importance of electrolytes in heart function.
They are essential for generating action potentials and maintaining proper heart rhythms
What happens during the refractory period?
The cardiac cells cannot respond to another stimulus until they recover.
What is the importance of excitability?
It allows cardiac cells to respond to external stimuli and generate electrical impulses.
Define the PR interval.
The time from the onset of atrial depolarization to the onset of ventricular depolarization.
Define refractory period.
The time after an action potential during which the cells cannot respond to another stimulus.
What happens when there is an imbalance of electrolytes?
It can lead to dysrhythmias and other cardiac issues.
How can conduction blocks affect heart rhythms?
They can cause slow or irregular heartbeats, leading to potential health risks.