What is cell depolarization in the heart?
Depolarization of the heart leads to the contraction of the heart muscles and therefore an EKG is an indirect indicator of heart muscle contraction. The cells of the heart will depolarize without an outside stimulus. This property of cardiac muscle tissue is called automaticity, or autorhythmicity.
What causes depolarization of cardiac muscle?
In nerve and muscle cells, the depolarization phase of the action potential is caused by an opening of fast sodium channels. This also occurs in non-pacemaker cardiac cells; however, in cardiac pacemaker cells, calcium ions are involved in the initial depolarization phase of the action potential.
What is the function of the Autorhythmic cells of the heart?
The autorhythmic cells serve as a pacemaker to initiate the cardiac cycle (pumping cycle of the heart) and provide a conduction system to coordinate the contraction of muscle cells throughout the heart.
Which is a depolarizing ion?
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 is heart 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.
Where does depolarization of the heart begin?
right atrium
The electrical event, the wave of depolarization, is the trigger for muscular contraction. The wave of depolarization begins in the right atrium, and the impulse spreads across the superior portions of both atria and then down through the contractile cells.
Which wave is caused by atria depolarization?
The P wave represents the electrical depolarization of the atria. In a healthy person, this originates at the sinoatrial node (SA node) and disperses into both left and right atria.
What causes depolarization of a cardiac muscle cell to occur quizlet?
Depolarization of cardiac muscle occurs when Na+ ions diffuse into the cell as voltage-gated Na+ ion channels open. Early repolarization of cardiac muscle cells occurs when voltage-gated Na+ ion channels close and voltage-gated K+ ion channels open.
What happens when cells depolarize?
In the process of depolarization, the negative internal charge of the cell temporarily becomes more positive (less negative). This shift from a negative to a more positive membrane potential occurs during several processes, including an action potential.
Why do Autorhythmic cells depolarize?
Autorhythmic cells begin depolarizing due to a slow continuous influx of sodium, and a reducedefflux of potassium. As sodium ions enter the cell, the inner surface of the plasma membrane gradually becomes lessnegative, generating the pacemaker potential.
What causes myocardial cells to depolarize at threshold?
Action potentials from pacemaker cells and other myocardial cells stimulate myocardial cells to go from their resting membrane potential of ~ -90 mV, to depolarize to threshold (~ -85mV). At threshold, fast Voltage-gated Na+ channelsopen causing a rapid depolarization as 1.
What is the production of action potentials in Autorhythmic cells?
Production of Action Potentials in Autorhythmic Cells •Action potentials of autorhythmic cells can be divided into three phases. Note,the numbering of these phases may seem odd, but they correspond to similar phases of cardiac myocyte action potentials. 4.
What is the depolarization phase of the action potential?
Phase 0 is the depolarization phase of the action potential. This is followed by phase 3 repolarization. Once the cell is completely repolarized at about -60 mV, the cycle is spontaneously repeated.