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The cardiac cycle is the performance of the human heart from the beginning of one heartbeat to the beginning of the next. [1] It consists of two periods: one during which the heart muscle relaxes and refills with blood, called diastole, following a period of robust contraction and pumping of blood, called systole. [1]
One of the simplest methods of assessing the heart's condition is to listen to it using a stethoscope. [1] In a healthy heart, there are only two audible heart sounds, called S1 and S2. The first heart sound S1, is the sound created by the closing of the atrioventricular valves during ventricular contraction and is normally described as "lub".
This process is of vital importance as it allows for the heart to beat in a controlled manner, without the need for conscious input. EC coupling results in the sequential contraction of the heart muscles that allows blood to be pumped, first to the lungs ( pulmonary circulation ) and then around the rest of the body ( systemic circulation ) at ...
The pumping action of the heart generates pulsatile blood flow, which is conducted into the arteries, across the micro-circulation and eventually, back via the venous system to the heart. During each heartbeat, systemic arterial blood pressure varies between a maximum and a minimum pressure. [33] In physiology, these are often simplified into ...
Coronary Artery Disease. Coronary artery disease, or coronary heart disease, is the most common type of heart disease. It occurs when fatty deposits called plaques build up in your arteries ...
A resting heart rate that is too fast – above 100 beats per minute in adults – is called tachycardia, and a resting heart rate that is too slow – below 60 beats per minute – is called bradycardia. [2] Some types of arrhythmias have no symptoms. [1] Symptoms, when present, may include palpitations or feeling a pause between heartbeats. [1]
The heart did not pump blood around, the heart's motion sucked blood in during diastole and the blood moved by the pulsation of the arteries themselves. [93] Galen believed the arterial blood was created by venous blood passing from the left ventricle to the right through 'pores' between the ventricles. [90]
Commotio cordis (Latin, "agitation / disruption of the heart") is a rare disruption of heart rhythm that occurs as a result of a blow to the area directly over the heart (the precordial region) at a critical instant during the cycle of a heartbeat. [1] The condition is 97% fatal if not treated within three minutes. [2]