What is propagation in cardiac muscle?
Propagation of excitation in the heart involves action potential (AP) generation by cardiac cells and its propagation in the multicellular tissue. AP conduction is the outcome of complex interactions between cellular electrical activity, electrical cell-to-cell communication, and the cardiac tissue structure.
What happens in phase 3 of cardiac action potential?
Repolarization (phase 3 of the action potential) occurs because of an increase in potassium permeability. At the SA node, potassium permeability can be further enhanced by vagal stimulation. This has the effect of hyperpolarizing the cell and reducing the rate of firing. Sympathetic stimulation has the opposite effect.
Which is the correct pathway for propagation of cardiac impulse?
The right pathway of the cardiac impulse is: SA node – AV node – Bundle of His – Purkinje Fibres.
How action potential is propagated?
The action potential propagates with essentially the same waveform all along the axon. The velocity of action potential propagation varies with myelination and axon size. In unmyelinated axons, the velocity varies approximately with the square root of axon diameter.
What happens during phase 4 of the cardiac cycle?
Phase IV: Period of isovolumetric relaxation—both valves are closed and intraventricular pressure decreases without any blood volume changes. The period of relaxation is called diastole in which the ventricle fills with blood and the period of ventricle contraction is called systole.
Which of the following is the correct sequence of events regarding the cardiac cycle?
Which of the following is the correct sequence of events regarding the cardiac cycle? isovolumic contraction, ejection, isovolumic relaxation, passive ventricular filling, active ventricular filling.
When the heart contracts this is due to an electrical change called?
Cards
| Term what is the correct order of the flow of blood entering the heart from the venae cavea? | Definition right atrium, right ventricle, pulmonary trunk, pulmonary veins, left atrium, left ventricle. |
|---|---|
| Term when the heart contracts, this is due to an electrical change called _____. | Definition depolarization |
What is depolarisation and repolarisation of the heart?
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.
How is action potential propagated along an axon?
The action potential generated at the axon hillock propagates as a wave along the axon. The currents flowing inwards at a point on the axon during an action potential spread out along the axon, and depolarize the adjacent sections of its membrane.
What are the 5 stages of the cardiac cycle?
Detailed descriptions of each phase can be obtained by clicking on each of the seven phases listed below.
- Phase 1 – Atrial Contraction.
- Phase 2 – Isovolumetric Contraction.
- Phase 3 – Rapid Ejection.
- Phase 4 – Reduced Ejection.
- Phase 5 – Isovolumetric Relaxation.
- Phase 6 – Rapid Filling.
- Phase 7 – Reduced Filling.
What happens during phase 3 of the cardiac action potential?
What is the propagation of cardiac action potential?
Cardiac Action Potential – Propagation. Macroscopically, this phenomenon manifests as a wave of depolarization which spreads across sections of myocardium from their initiation point. An important feature of this action potential wave is that it does not bounce back and forth throughout the myocardium once initiated.
What is the pathway of cardiac contraction?
Heart Contraction Cardiac contraction is the end result of action potentials that are initiated at the sinoatrial node by the spontaneous depolarization of the nodal cells to threshold and the subsequent transmission of triggered action potentials in different cells of the cardiac conduction pathway to the atrial and ventricular muscle fibers.
What is the pathway of action potentials through the heart?
Each cardiac muscle cell fires an action potential as a result of excitation propagated from the sinoatrial node, which produces muscle cell contraction. A wave of action potentials spreads across the organ to produce coordinated contraction of the heart and efficient ejection of blood to the body.
What is cardiac action potential and why is it important?
Cardiac action potential. Rate dependence of the action potential is a fundamental property of cardiac cells and alterations can lead to severe cardiac diseases including cardiac arrhythmia and sometimes sudden death. Action potential activity within the heart can be recorded to produce an electrocardiogram (ECG).