Last update:

Phases of the Cardiac Cycle

Phases of the Cardiac Cycle:

  1. As the ventricles relax from the previous cycle, blood image descriptionpassively flows into the ventricles from the atria through the open atrioventricular (AV) valves.
Movement of the heart valves animation slide 1
Movement of the heart valves animation slide 2
Movement of the heart valves animation slide 3
Movement of the heart valves animation slide 4
Movement of the heart valves animation slide 5
Movement of the heart valves animation slide 6
Blood passively flowing into the ventricles from the atria.
  1. Both image descriptionatria contract (atria systole) to forcibly fill the ventricles with blood.
Movement of the heart valves animation slide 6
Movement of the heart valves animation slide 7
Movement of the heart valves animation slide 8
Movement of the heart valves animation slide 9
Movement of the heart valves animation slide 10
Movement of the heart valves animation slide 11
Atria contracting and forcibly filling the ventricles with blood.
  1. The image descriptionventricles begin to contract (ventricular systole) after they are filled, which increases the intraventricular pressure. In response, the AV valves move upward and block blood from flowing back into the relaxing atria.
Movement of the heart valves animation slide 11
Movement of the heart valves animation slide 12
Movement of the heart valves animation slide 13
The ventricles contracting and the AV valves moving upward.
  1. The image descriptionsemilunar valves open due to continued ventricular contraction and rising intraventricular pressure. Blood enters the aorta and pulmonary trunk arteries and is then distributed through-out the body.
Movement of the heart valves animation slide 13
Movement of the heart valves animation slide 14
Movement of the heart valves animation slide 15
Movement of the heart valves animation slide 16
Movement of the heart valves animation slide 17
The semilunar valves open and blood enters the aorta and pulmonary trunk arteries.
  1. After they contract, the ventricles enter a period of relaxation (ventricular diastole). The intraventricular pressure drops and blood in the large arteries reverses flow. This forces the image descriptionsemilunar valves to close, which prevents blood from entering the ventricles.
Movement of the heart valves animation slide 17
Movement of the heart valves animation slide 18
Movement of the heart valves animation slide 20
Blood in the large arteries reverses flow, forcing the semilunar valves to close.
  1. The drop in ventricular pressure also allows the AV valves to re-open and a image descriptionnew cycle begins.
Movement of the heart valves animation slide 1
Movement of the heart valves animation slide 2
Movement of the heart valves animation slide 3
Movement of the heart valves animation slide 4
Movement of the heart valves animation slide 5
Movement of the heart valves animation slide 6
Movement of the heart valves animation slide 7
Movement of the heart valves animation slide 8
Movement of the heart valves animation slide 9
Movement of the heart valves animation slide 10
Movement of the heart valves animation slide 11
Movement of the heart valves animation slide 12
Movement of the heart valves animation slide 13
Movement of the heart valves animation slide 14
Movement of the heart valves animation slide 15
Movement of the heart valves animation slide 16
Movement of the heart valves animation slide 17
Movement of the heart valves animation slide 18
Movement of the heart valves animation slide 20
The cardiac cycle beginning anew.