Cardiac Depolarization and Repolarization Flashcards

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Questions and Answers

What are ions?

Charged particles

What is a polarized cell?

Negatively charged resting cardiac cell, electrically negative on the inside compared to the outside

What does extracellular refer to?

Sodium ions outside the cell

What does intracellular refer to?

Potassium ions inside the cell Signup and view all the answers

What is depolarization?

Occurs when sodium rushes into the cell, resulting in a positive electrical charge and the start of electrical current flow Signup and view all the answers

What is the function of the sodium-potassium pump?

An active transport system that returns the cell to its negative charge, moves potassium into the cell and sodium out of the cell Signup and view all the answers

What is conduction in the context of cardiac cells?

When positive ions move adjacent cells Signup and view all the answers

What is repolarization?

Cell is returned to its resting negative charge Signup and view all the answers

What is transmembrane potential?

The electrical charge at the cell membrane Signup and view all the answers

What is phase 4 in cardiac cells?

Cardiac cell is at rest Signup and view all the answers

What happens in phase 0 of cardiac cells?

Cardiac cell is stimulated, sodium rushes into cell Signup and view all the answers

What does the QRS complex represent?

A spike waveform that represents depolarization of the ventricular myocardium Signup and view all the answers

What occurs during phases 1 and 2 of cardiac activity?

Early repolarization, calcium is released in these 2 phases, resulting in ventricular contraction Signup and view all the answers

What is phase 3 in cardiac cells?

Rapid repolarization, sodium and potassium return to normal places via sodium-potassium pump, thus returning to its resting negative charge Signup and view all the answers

What does refraction mean in cardiac physiology?

Resist to Signup and view all the answers

What is absolute refraction?

Cells cannot accept another impulse because they are still dealing with the last one. Absolutely no stimulus, no matter how strong, will result in another depolarization Signup and view all the answers

What is relative refraction?

A strong stimulus will result in depolarization that the cardiac cell is 'hyper' Signup and view all the answers

What does the P wave represent?

Represents atrial depolarization, which results in atrial contraction Signup and view all the answers

What does the Ta wave represent?

Represents atrial repolarization, usually not seen occurs at the same time as the QRS complex Signup and view all the answers

What does the T wave represent?

Represents ventricular repolarization, broad and rounded Signup and view all the answers

What does the U wave represent?

Represents late ventricular repolarization and is not normally seen Signup and view all the answers

What is the PR segment/ST segment?

Space between QRS and T wave Signup and view all the answers

What is the baseline/isoelectric line?

Flat line between T wave of one beat and the P wave of the next beat Signup and view all the answers

What does the Q wave represent?

A negative deflection (wave) that occurs before a positive deflection Signup and view all the answers

What does the R wave/R prime represent?

Any positive deflection Signup and view all the answers

What does the S wave represent?

Negative deflection that follows an R wave Signup and view all the answers

What does the QS wave represent?

A negative deflection with no positive deflection at all Signup and view all the answers

Study Notes

Ions and Polarization

Ions are charged particles crucial for electrical signaling in cells.
A polarized cell is negatively charged at rest, with an internal electrical negativity compared to the external environment.

Cellular Ion Distribution

Extracellular refers to sodium ions located outside the cell.
Intracellular refers to potassium ions located inside the cell.

Depolarization Process

Depolarization occurs when sodium rushes into the cell, causing a positive electrical charge and initiating electrical current flow.
The sodium-potassium pump actively transports sodium out and potassium into the cell, restoring the negative charge post-depolarization.

Electrical Conduction

Conduction refers to the movement of positive ions to adjacent cells, facilitating the electrical signals.
Repolarization is the process of returning the cell to its resting negative charge after an action potential.

Phases of Cardiac Action Potentials

Phase 4: Cardiac cell is at rest.
Phase 0: Stimulation of the cardiac cell, marked by a rush of sodium into the cell.
Phases 1 & 2: Early repolarization where calcium is released, resulting in ventricular contraction.
Phase 3: Rapid repolarization occurs, with sodium and potassium returning to their normal locations via the sodium-potassium pump.

Refractory Periods

Absolute refractory period: Cells cannot accept another impulse as they are still recovering; no stimulus will result in depolarization.
Relative refractory period: A strong stimulus can induce depolarization as the cardiac cell is "hyper."

ECG Waveforms

P wave: Represents atrial depolarization, leading to atrial contraction.
QRS complex: Indicates ventricular depolarization, characterized by a spiked appearance.
T wave: Represents ventricular repolarization, typically broad and rounded.
U wave: Represents late ventricular repolarization, rarely seen.
PR segment/ST segment: Denotes the space between the QRS complex and the T wave.
Baseline/isoelectric line: The flat line found between the T wave of one heartbeat and the P wave of the next.

Wave Definitions

Q wave: Negative deflection that appears before any positive deflection.
R wave/R prime: Any positive deflection observed in the ECG.
S wave: Negative deflection that follows an R wave.
QS wave: A negative deflection with no preceding positive deflection.

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Description

Test your understanding of key terms related to cardiac depolarization and repolarization with these flashcards. Each card provides a word along with its definition, focusing on concepts such as ions, polarized cells, and their respective roles in cellular processes.