What is cardiac depolarization and repolarization?
Depolarization with corresponding contraction of myocardial muscle moves as a wave through the heart. 7. Repolarization is the return of the ions to their previous resting state, which corresponds with relaxation of the myocardial muscle. 8.
What is the best definition of depolarization?
1 : the process of depolarizing something or the state of being depolarized. 2 physiology : loss of the difference in charge between the inside and outside of the plasma membrane of a muscle or nerve cell due to a change in permeability and migration of sodium ions to the interior …
What happens during depolarization of the heart?
Depolarization occurs in the four chambers of the heart: both atria first, and then both ventricles. The sinoatrial (SA) node on the wall of the right atrium initiates depolarization in the right and left atria, causing contraction, which corresponds to the P wave on an electrocardiogram.
What causes depolarization in the heart?
Myocardial contraction begins when sodium channels open and positively charged sodium ions flow into the cell and cause membrane depolarization (phase 0).
What is difference between depolarization and repolarization?
Depolarization refers to the movement of a cell’s membrane potential to a more positive value while repolarization refers to the change in membrane potential, returning to a negative value.
What does depolarization mean in ECG?
A wave of depolarization traveling toward a positive electrode results in a positive deflection in the ECG trace. A wave of depolarization traveling away from a positive electrode results in a negative deflection. A wave of repolarization traveling toward a positive electrode results in a negative deflection.
Does depolarization mean relaxation?
When the electrical signal of a depolarization reaches the contractile cells, they contract. When the repolarization signal reaches the myocardial cells, they relax. Thus, the electrical signals cause the mechanical pumping action of the heart.
What’s the difference between repolarization and depolarization?
Depolarization is caused when positively charged sodium ions rush into a neuron with the opening of voltage-gated sodium channels. Repolarization is caused by the closing of sodium ion channels and the opening of potassium ion channels.
What happens during repolarization?
Repolarization is a stage of an action potential in which the cell experiences a decrease of voltage due to the efflux of potassium (K+) ions along its electrochemical gradient. This phase occurs after the cell reaches its highest voltage from depolarization.
What is meant by repolarization?
: restoration of the difference in charge between the inside and outside of the cell membrane following depolarization.
Is depolarization positive or negative?
Depolarization brings positive charge inside the cells in an activation step, thus changing the membrane potential from a negative value (approximately −60mV) to a positive value (+40mV).
What is the difference between depolarization and repolarization of the heart?
Depolarization of the heart is the orderly passage of electrical current sequentially through the heart muscle, changing it, Repolarization of the heart is the orderly return of each cell to its polarized state, cell by cell, until all are polarized again.
What is depolarization of the heart?
Depolarization of the heart is the orderly passage of electrical current sequentially through the heart muscle, changing it, cell by cell, from the resting polarized state to the depolarized state until the entire heart is depolarized.
What is cardiac polarization?
Polarization is the resting state of the heart. During the resting phase of the cardiac cycle, the outer portion of the cardiac cells has a positive charge, while the inner portion of the cardiac cell is negatively charge.
What is depolarization EKG?
Electrocardiogram (EKG, ECG) General Description. As the heart undergoes depolarization and repolarization, the electrical currents that are generated spread not only within the heart, but also throughout the body. This electrical activity generated by the heart can be measured by an array of electrodes placed on the body surface.
