Compressional waves are also called P-Waves, (P stands for “primary”) because they are always the first to arrive. They gave us the first jolt last Friday. Shear waves propagate more slowly through the Earth than compressional waves and arrive second, hence their name S- or secondary waves.
What activity does the P wave represent?
The P wave represents the depolarization of the left and right atrium and also corresponds to atrial contraction. Strictly speaking, the atria contract a split second after the P wave begins. Because it is so small, atrial repolarization is usually not visible on ECG.
What is P wave in heart?
The first wave (p wave) represents atrial depolarisation. When the valves between the atria and ventricles open, 70% of the blood in the atria falls through with the aid of gravity, but mainly due to suction caused by the ventricles as they expand.
What type of wave is P wave?
P Waves. P waves are compressional waves that do not produce much damage. They can move through any type of material and travel at almost twice the speed of S waves. High frequency P waves do not weaken, or “attenuate,” as rapidly as S waves so they retain higher frequencies when they arrive at seismic stations.
What is P wave and S wave referring to earthquake?
In P or compressional waves, the vibration of the rock is in the direction of propagation. P waves travel fastest and are the first to arrive from the earthquake. In S or shear waves, rock oscillates perpendicular to the direction of wave propagation.
What does each wave represent in an ECG?
The different waves that comprise the ECG represent the sequence of depolarization and repolarization of the atria and ventricles.
Is depolarization a contraction?
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 happens during P wave of cardiac cycle?
The P wave represents depolarization of the atria and is followed by atrial contraction (systole). Atrial systole extends until the QRS complex, at which point, the atria relax. The QRS complex represents depolarization of the ventricles and is followed by ventricular contraction.
What do you see in P waves before QRS?
The presence of P waves immediately before every QRS complex indicates sinus rhythm. If there are no P waves, note whether the QRS complexes are wide or narrow, regular or irregular.
Which wave is ventricular repolarization?
The T wave on the ECG (T-ECG) represents repolarization of the ventricular myocardium.
What does the PR segment represent?
The PR segment represents the electrical conduction through the atria and the delay of the electrical impulse in the atrioventricular node.
Where is the P wave?
The P wave occurs when the sinus node, also known as the sinoatrial node, creates an action potential that depolarizes the atria. The P wave should be upright in lead II if the action potential is originating from the SA node. In this setting, the ECG is said to demonstrate a normal sinus rhythm, or NSR.
How do P waves travel?
P waves travel through rock the same way that sound waves do through air. That is, they move as pressure waves. When a pressure wave passes a certain point, the material it is passing through moves forward, then back, along the same path that the wave is traveling. P waves can travel through solids, liquids and gases.
What are two characteristics of P waves?
P waves, or Primary waves, are the first waves to arrive at a seismograph. P waves are the fastest seismic waves and can move through solid, liquid, or gas. They leave behind a trail of compressions and rarefactions on the medium they move through. P waves are also called pressure waves for this reason.
