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19.8 Cardiac Cycle
A&P 19.8 Cardiac Cycle
| Question | Answer |
|---|---|
| What is the Cardiac cycle? | All events in heart from the start of one heart beat to the start of the next |
| What does the Cardiac Cycle include? | Systole (contraction) and Diastole (relaxation) |
| When does pressure increase? | During contractions, and decreases during relaxation |
| In what direction does blood move down? | its pressure gradient (high to low) |
| What do valves do? | Ensure that blood flow is forward (closure prevents backflow) |
| What RAISES ventricular pressure? | Ventricular contraction |
| What happens to the valves during ventricular contraction? | AV valves pushed closed; Semilunar valves pushed open and blood ejected to artery |
| What LOWERS ventricular pressure? | Ventricular relaxation |
| What happens to the valves during ventricular relaxation? | Semilunar valves are closed (b/c no pressure from below keeping them open) and AV valves are open (b/c no pressure pushing them closed) |
| What are the events of atrial contraction and ventricular filling? | SA node starts atrial excitation/contraction pushing blood into ventricles to be filled to end-diastolic volume (EDV). Atria relax for remainder of cardiac cycle |
| What happens in Isovolumetric contraction? | Purkinje fibers initiate ventricular excitation/contractions so pressure rises and AV valves are pushed closed. Ventricular pressure is still less than atrial trunk pressure, so semilunar valves are still closed. |
| Why does the ventricles continue to contract during ventricular ejection? | So that ventricular pressure rises above arterial pressure |
| When are the semilunar valves forced open? | As blood moves from ventricles to aterial trunks |
| What is stroke volume (SV)? | Amount of blood ejected by ventricule |
| What is "incorrect" def of End systolic Volume (ESV)? | Amount of blood remaining in ventricle after contraction finishes. |
| What is the equation for ESV? | EDV - SV ; Ex: 60 mL = 130 mL - 70 mL |
| What is the definition of isovolumetric? | The time when all valves are closed , blood neither enters nor leaves |
| What are the AV valves doing during isovolumetric relaxation? | AV valves remain closed |
| What does the atrial blood pressure do during atrial relaxation and ventricular filling? | forces AV valves open and blood flows into ventricles |
| What do the semilunar valves do during atrial relaxation and ventricular filling? | Remain closed since arterial pressure is greater than ventricular pressure |
Created by:
elizabethcosio
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