The first sound of a heartbeat is caused by the closing of the atrioventricular valves (mitral and tricuspid valves) in the heart and marks the beginning of ventricular systole, where the ventricles contract to pump blood. This sound is known as the "lub" sound of the heartbeat.
A heartbeat produces the familiar "LUB-DUP" sounds as the chambers contract and the valves close. The first heart sound, "lub," is heard when the ventricles contract and the atrioventricular valves close. This sound last longest and has a lower pitch. The second heart sound, "dub," is heard when the relaxation of the ventricles allows the semilunar valves to close.
"Lub dub" is the sound the human heart makes as blood passes through it.
The sounds LUB and DUB (also dup) are used to indicate a human heartbeat, with the LUB sound made by the closing of atrioventricular valves, and the DUB by the closing of the exterior or semilunar valves (aortic valves and pulmonary valve).
The two heartbeat sounds are the lub-dub sound. The "lub" sound is caused by the closing of the heart's mitral and tricuspid valves, while the "dub" sound is caused by the closing of the aortic and pulmonary valves.
there are 2 sounds the heart makes. "lub-dub" the first ("lub") is when the atrioventricular valves sclose the second ("dub") is when the semilunar valves close
The 'lub' is the S1 sound. It occurs due to normal closure of the mitral and tricuspid (atrioventricular) valves. With these valves closed, systole commences and blood is actively squeezed from the ventricles. The second sound is the 'dub' or S2 sound. It occurs as the aortic (to LV) and pulmonary (to RV) valves close to prevent backflow from the blood ejected from the ventricles and marks the beginning of diastole (or filling) of the heart.
The heart valves.
heart pump
lub dub lub dub
The atria and ventricles work together, alternately contracting and relaxing to pump blood through your heart. The electrical system of your heart is the power source that makes this possible. Your heartbeat is triggered by electrical impulses that travel down a special pathway through the heart.
S1 makes a "lub" sound. It is the first heart sound in a normal rhythm. The sound is produced when the AV valves close.