What are the steps of action potential in the heart?
Membrane currents that generate the a normal action potential. Resting (4), upstroke (0), early repolarization (1), plateau (2), and final repolarization are the 5 phases of the action potential.
What is the path of an action potential through the cardiac conduction system?
The action potential generated by the SA node then travels through the right atrium via the internodal pathway, and to the left atrium via Bachmann’s bundle. As the action potential travels through the atria, the atrial contractile myocytes depolarize and contract.
What ion causes depolarization in the heart?
Sodium ions continue to diffuse into the cells of SA node. When the membrane potential becomes greater than the threshold potential, it causes the opening of Ca+2 channels. The calcium ions then rush in, causing depolarization. depolarization and contraction of ventricles.
What are the key differences between a cardiac action potential and the action potential of a neuron?
Cardiac action potentials in the heart differ considerably from action potentials found in neural and skeletal muscle cells. One major difference is in the duration of the action potentials. In a typical nerve, the action potential duration is about 1 ms.
What is the electrical pathway of the heart?
The electrical impulse travels from the sinus node to the atrioventricular node (also called AV node). There, impulses are slowed down for a very short period, then continue down the conduction pathway via the bundle of His into the ventricles.
What is the electrical pathway of the heart in order?
The SA node (called the pacemaker of the heart) sends out an electrical impulse. The upper heart chambers (atria) contract. The AV node sends an impulse into the ventricles. The lower heart chambers (ventricles) contract or pump.
What is the process of depolarization in 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.
Where does the action potential occur in a cardiac cell?
The action potential occurs in all cardiac cells but its appearance varies depending on cell type. During de- and repolarization ions (Na+ [sodium], K+ [potassium] and Ca2+ [calcium]) flows back and forth across the cell membrane. Because ions are electrically charged, their movement generates an electrical current.
How does the electrical conduction system of the heart work?
The electrical conduction system of the heart transmits signals generated usually by the sinoatrial node to cause contraction of the heart muscle.
Where does the electrical charge start in the heart?
As cell after cell rapidly transmits the electrical charge, the entire heart contracts in one coordinated motion, creating a heartbeat. The electrical signal starts in a group of cells at the top of your heart called the sinoatrial (SA) node.
How is the pumping action of the heart regulated?
The heart’s pumping action is regulated by an electrical conduction system that coordinates the contraction of the various chambers of the heart. How does the heart beat? An electrical stimulus is generated by the sinus node (also called the sinoatrial node, or SA node).
