Cardiovascular L3: The Cardiac cycle & Heart sounds Flashcards
The cardiac cycle is the period between _______ and the next
one heartbeat
How is the pattern of the cardiac cycle defined?
Valves
What are the functions of valves?
Makes sure that when the heart contracts, blood only goes in one direction and can’t flow back
In each cycle, the atria and ventricles undergo separate phases of ______ and ________.
systole (contraction); diastole (relaxation)
To ensure forward blood flow and prevent backwards flow, the heart has two sets of valves: ________ and _________.
atrioventricular (AV; tricuspid & mitral); semilunar valves (aortic and pulmonary)
When will a valve open?
A valve will open if the pressure behind it is greater than the pressure in front of it
A valve will open if the pressure behind it is ______ (greater/lower) than the pressure in front of it, and close if pressure behind is _____ (greater/lower)
greater; lower
When will a valve close?
If pressure behind is lower
Where are the 4 major valves located?
What does a tricuspid valve mean/look like?
3 parts
What does a bicuspid or ‘mitral’ valve look like?
2 parts
What does an aortic or pulmonary valve look like?
semilunar valves
Heart valves only open in one direction. True or false. Why?
True- can’t open backwards- chordae tendinae (helps)
What are 2 problems/damage with the valves?
- Stenosis (not opening properly)
- Regurgitation (can’t close properly)
What are the 4 phases within the cardiac cycle?
- Ventricular diastole: ventricles fill with blood
- Isovolumetric ventricular contraction: ventricles contract, all four valves are closed, pressure rises
- Ventricular ejection: pressure forces blood past the semilunar valves
- Isovolumetric ventricular relaxation: pressure falls, initially isovolumetric, but then AV valves open and filling begins again
What happens when combining electrical, pressure and volumetric components of cradiac cycle?
What are the 9 steps of the left ventricular pressure-volume loop?
- The AV valve opens
- Passive ventricular filling occurs Big increase in volume, but slight increase in pressure
- Atrial contraction completes ventricular filling. End-diastolic volume is reached
- The AV valve closes
- Isovolumetric ventricular contraction occurs. Volume remains constant; pressure increases markedly
- The aortic valve opens
- Stroke volume ejected. Endsystolic volume is reached
- The aortic valve closes
- Isovolumetric ventricular relaxation occurs. Volume constant; pressure falls sharply
What is stroke volume?
Volume that is actually ejected