In this animation it depicts an artery with cholesterol plaque (the yellowish area) which is blocking most of the inside of this artery. Then small cells called platelets become clumped together and cause the red blood cells to form a clot. This is what causes a HEART ATTACK.

The anatomy and function of the heart

Normal Heart Sounds With the aid of a stethoscope you can hear the characteristic sounds of the normal heartbeat, typically described as a "lub-dub." These sounds are produced by the closure of the heart valves. The first heart sound or "lub" results from closure of the tricuspid and mitral valves. It is a rather low-pitched and a relatively long sound which, as indicated in, represents the beginning of ventricular systole. The second heart sound, or "dub," marks the beginning of ventricular diastole. It is produced by closure of the aortic and pulmonary (pulmonic) semilunar vanes when the intraventricular pressure begins to fall. This "dub" sound is typically heard as a sharp snap because the semilunar valves tend to close much more rapidly than the AV valves. Because diastole occupies more time than systole, a brief pause occurs after the second heart sound when the heart is beating at a normal rate. Therefore, the pattern that one hears is one of: "lub-dub" pause, "lub-dub" pause, and so on. Sometimes, especially in young normal individuals, a third heart sound can be heard. This sound is produced by the very rapid influx of blood into the partially filled ventricle. It is typically very faint and as such difficult to hear.

How to deal with heart attack and with stroke

Examination of the heart from the USMLE collection

Heart sounds S3, S4

Heart sounds S1, S2

Auscultation of the heart

Review of heart sounds

Examination of the heart

Fetal heart sound by sonique

Examination of the heart and lungs with heart sounds

full examination of the heart