Cardiac Ion Channels | Circulation: Arrhythmia and Electrophysiology
1. Phase 4, or the resting potential, is stable at ≈−90 mV in normal working myocardial cells. 2. Phase 0 is the phase of rapid depolarization. The membrane potential shifts into positive voltage range. This phase is central to rapid propagation of the cardiac impulse (conduction velocity, θ=1 m/s). 3. Phase 1 is a phase of rapid repolarization.
Depolarization vs. Repolarization of the Heart (2024)
2024年10月18日 · Depolarization is caused by the influx of sodium (Na+) ions into the heart cells, making the inside of the cells more positive and triggering contraction. Repolarization occurs when potassium (K+) ions leave the cells, restoring …
17.3A: Mechanism and Contraction Events of Cardiac Muscle Fibers
Similarly to skeletal muscle, the influx of sodium ions causes an initial depolarization; however, in cardiac muscle, the influx of calcium ions sustains the depolarization so that it lasts longer.
Physiology, Cardiac Muscle - StatPearls - NCBI Bookshelf
2023年7月30日 · Action potentials travel along the sarcolemma and into the t-tubules to depolarize the membrane. Voltage-sensitive dihydropyridine (DHP) receptors on t-tubules allow calcium influx into the cell via L-type (long-lasting) calcium channels during the plateau phase (phase 2) of the action potential.
Cardiac Muscle and Electrical Activity – Anatomy & Physiology
The large QRS complex represents the depolarization of the ventricles, which requires a much stronger electrical signal because of the larger size of the ventricular cardiac muscle. The ventricles begin to contract as the QRS reaches the peak of the R wave.
Cardiac electrophysiology: Action potential, automaticity and …
The depolarization spreads from the sinoatrial node to the atrial and ventricular myocardium. Propagation of the action potential is possible because all cardiac cells are electrically interconnected by gap junctions (Figure 1).
Physiology, Cardiac Repolarization Dispersion and Reserve
2023年4月17日 · In the heart, the wave of depolarization current originates in the SA node under normal conditions and reaches the ventricular myocardium via the conduction system. Anatomically the ventricular depolarization travels from …
Cardiac muscle physiology | BJA Education | Oxford Academic
2007年5月3日 · During phase 1, there is partial repolarization, because of a decrease in sodium permeability. Phase 2 is the plateau phase of the cardiac action potential. Membrane permeability to calcium increases during this phase, maintaining depolarization and …
Cardiac muscle cells – Basic Human Physiology
The cardiac muscle cells have a much different action potential. In this case, there is a rapid depolarization, followed by a brief repolarization and plateau phases, ending with a full repolarization.
Signaling in Muscle Contraction - PMC - PubMed Central (PMC)
In cardiac muscle, depolarization starts in the pacemaker cells (modified cardiac myocytes that set the heart rate and are rich in signaling molecules) in the sinoatrial node, which is innervated by both parasympathetic and sympathetic nerves.