What is the cardiac cycle? - ✔️✔️one complete and contraction and relaxation
What does the heart do during a cardiac cycle? - ✔️✔️contracts and relaxes
what are the two primary phases of the cardiac cycle? - ✔️✔️diastole and systole
What is diastole? - ✔️✔️the time during which cardiac muscle relaxes
What is systole? - ✔️✔️the time during which cardiac muscle contracts
what are the 5 phases the cardiac cycle is divided into? - ✔️✔️- the heart at rest (atrial and ventricular
diastole, late diastole)
- completion of ventricular filling (atrial systole)
- early ventricular contraction (isovolumetric ventricular contraction)
- the heart pumps (ventricular ejection)
- ventricular relaxation (isovolumetric ventricular relaxation, early diastole)
what happens in the first phase of the cardiac cycle (late diastole)? - ✔️✔️- cycle starts with atria relaxed
and filling with blood from veins
- the ventricles begin to relax, when the ventricles are sufficiently relaxed and pressure in atria exceeds
ventricles, AV valve opens and ventricles passively fill with blood from atria
what happens in the second phase of the cardiac cycle (atrial systole)? - ✔️✔️- most blood enters
ventricles passively but under normal resting conditions the last about 20% enters when the atria
contract.
, what happens in the third phase of the cardiac cycle (isovolumetric ventricular contraction)? - ✔️✔️- the
ventricles being to contract, this builds up pressure i the ventricles and causes the AV valves to snap
shut (first heart sound s1 "lub")
- both valves are now closed and then the ventricle continues to contract building up pressure
What happens in the fourth phase of the cardiac cycle (ventricular ejection)? - ✔️✔️- as ventricles
contract pressure in the ventricle exceeds pressure in the outflow arteries (aorta or pulmonary arteries)
causing the semi lunar valves to open and blood to flow out
what happens during the fifth phase of the cardiac cycle (isovolumetric ventricular relaxation)? - ✔️✔️-
the ventricles then begin to relax, pressure in the outflow arteries begins to exceed the ventricles
causing blood to attempt to flow backward into the ventricles causing the semi lunar valves to snap shut
(second heart sound s2 "dub")
what happens from the A-A' segment (late diastole)? - ✔️✔️- starts at ESV
- pressure in ventricle is lower than atria and the AV valve opens causing the ventricle to passively fill
with blood (majority is passive)
what happens from the A'-B segment (atrial systole)? - ✔️✔️- atria contracts forcing more blood into the
ventricle slightly increasing volume and pressure
- at the end of segment A'-B the maximal amount of blood is in the ventricles, this occurs at the end of
ventricular diastole and is termed the end diastolic volume
what happens from the B-C segment (isovolumetric contraction)? - ✔️✔️- the ventricle begins contracting
closing AV valve, continues contraction causes a large increase in pressure within the ventricles
- no change in volume
What happens from the C-D segment (ventricular ejection)? - ✔️✔️- once pressure in ventricles rises
above about 80mm Hg, it exceeds the aorta and the aortic valve opens causing a rapid ejection of blood
- pressure still rises as the ventricle continues to contract
- part way through this segment the ventricle begins to relax and pressure begins to drop but blood still
flows due to the inertia
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