Cardiac cycle
- Created by: z_mills1
- Created on: 05-06-14 19:33
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- Cardiac cycle
- each cycle takes approximately 0.8 seconds and occurs 72 times per min (on avg.)
- Diastole - relaxation phase - 0.5s
- Systole - contraction phase - 0.3s
- 2. Ventricular diastole
- as soon as AV valves open the 2nd stage occurs
- as ventricles fill with blood the semi-lunar valves remain shut. - atria now contracts
- 4. Ventricular systole
- ventricular pressure increases - overcomes pressure in aorta and pulmonary artery
- semi-lunar valves open - ventricles contract
- blood from right ventricle - pulmonary artery
- blood from left ventricle - aorta
- once completed the semi-lunar valves close
- 1. Atrial diastole
- upper chambers of the heart are filled with blood returning from:
- the body via the vena cava to the right atrium
- the lungs via the pulmonary vein to the left atrium
- atrio-ventricular (AV) valves are shut, but as volume of blood increases the AV valves open
- upper chambers of the heart are filled with blood returning from:
- 3. Atrial systole
- as atria contract, atrial systole occurs - ensures all the blood is emptied in to the ventricles
- the pressure increases - AV valves shut
- each cycle takes approximately 0.8 seconds and occurs 72 times per min (on avg.)
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