When exercising, we all know that the heart supplies us with blood around the body that carries oxygen to make us work. But what is the cycle of the blood and how does it work? The basic structure of the heart is:

The heart is divided into 2 halves, each work as a pump:

The right side = Pulmonary circuit pump (blood returning from the body is oxygen-deficient and carbon dioxide-rich)
The left side = Systemic circuit pump (oxygenated blood, pumps around body leaves heart via aorta)

The basic cardiac cycle involves these 3 stages:

  1. The heart muscle relaxes (both atria fill up with blood from the veins)
  2. The atria contract, and blood is forced into the ventricles
  3. The ventricles contract (the bicuspid and tricuspid valves from the atria close).  Blood is forced out of the heart and into the arteries

Some definitions of words that are used throughout this…

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