Cardiac Cycle Flashcards
(55 cards)
What does the cardiac cycle consist of?
- contraction = systole
*relaxation = diastole
What stages occur in the mid to late diastole?
*ventricular filling
*atrial contraction
What stages occur in the ventricular systole?
*isovolumetric contraction point
*ventricular ejection phase
What phase happens in early diastole?
*isovolumetric relaxation
What happens during ventricular (atrial) filling?
*atrial diastole
*ventricular diastole
Relaxation Phase: Both the atria and ventricles are in a relaxed state, allowing them
to fill with blood.
*Blood Inflow: The atria receive blood from the body and lungs, while the ventricles
passively fill with blood from the atria.
*Atrioventricular Valves: The tricuspid and mitral valves remain open to facilitate the
flow of blood into the ventricles.
What happens in atrial diastole?
*relaxes + fills with blood
* Right Atrium: Receives deoxygenated blood from the body via the
superior and inferior vena cava.
* Left Atrium: Receives oxygenated blood from the lungs via the pulmonary
veins.
What happens in ventricular diastole?
- Passive Filling: Blood flows passively from the atria into the ventricles
through the open atrioventricular (AV) valves (tricuspid valve on the right
side and mitral valve on the left side). - Rapid Filling Phase: Initially, blood flows quickly due to the pressure
difference between the atria and ventricles
What happens in ventricular systole of the isovolumetric contraction?
- Contraction: The ventricles begin to contract, increasing the pressure
within the chambers. - Valve Status: Both the atrioventricular (tricuspid and mitral) valves and
the semilunar (aortic and pulmonary) valves are closed. - Pressure Buildup: As the ventricles contract, the pressure rises rapidly.
what happens in the transition to ejection phase?
- Transition to Ejection Phase:
- Pressure Surpasses: When the pressure in the ventricles exceeds the
pressure in the aorta and pulmonary artery, the semilunar valves open.
What happens during ventricular ejection?
- Semilunar Valves Open: With the increased pressure, the aortic and
pulmonary valves open. - Blood Ejection: Blood is expelled from the ventricles into the aorta and
pulmonary artery.
What happens during isovolumetric relaxation?
- Ventricular Diastole:
- Relaxation: The ventricles begin to relax after the ejection of blood.
- Valve Status: Both the aortic and pulmonary valves close to prevent
backflow of blood into the ventricles. - Pressure Changes:
- Pressure Drop: As the ventricles relax, the pressure within them drops
rapidly. - Closed Valves: The atrioventricular valves (tricuspid and mitral) remain
closed during this phase, ensuring that the blood does not flow back into
the atria.
What are the two AV valves?
*tricuspid valve
*mitral valves
What do the AV valves do during the ventricular filling and atrial contraction?
- The AV valves are open, allowing blood to flow from the
atria into the ventricles. - During atrial contraction, the atria push the remaining blood into the ventricles, ensuring they are fully filled.
What do the AV valves do during isovolumetric contraction?
The AV valves close as the ventricles begin to contract,
preventing backflow of blood into the atria
What do the AV valves do during isovolumetric relaxation?
The AV valves remain closed until the pressure in the
ventricles drops below the pressure in the atria, at which
point they open to allow ventricular filling
What makes up the semi-lunar valves?
*pulmonary + aortic valves
What do the semi-lunar valves do during isovolumetric contraction?
The semilunar valves remain closed as the pressure builds
in the ventricles
What do the SL valves do during ventricular ejection?
When the pressure in the ventricles exceeds the pressure in
the pulmonary artery and aorta, the semilunar valves open,
allowing blood to be ejected into these arteries
What do the SL valves do during isovolumetric relaxation?
The semilunar valves close as the ventricles relax,
preventing the backflow of blood from the arteries back
into the ventricles
How does atrial pressure differ in the cardiac cycle?
- Increases during atrial systole.
- Decreases during ventricular systole and remains low during ventricular
filling
How does ventricular pressure differ during the cardiac cycle?
- Low during diastole (filling phase).
- Rapidly increases during isovolumetric contraction.
- Peaks during ventricular ejection.
- Rapidly decreases during isovolumetric relaxation
How does aortic pressure differ during the cardiac cycle?
- High and stable during ventricular diastole.
- Increases and peaks during ventricular ejection.
- Briefly rises (dicrotic notch) during isovolumetric relaxation due to the
closure of the aortic valve. - Gradually decreases during the rest of the diastole
Describe all the characteristics to dow with the S1 heartbeat sound
*Cause: Closure of the mitral and tricuspid valves.
*Timing: Occurs at the beginning of isovolumetric ventricular contraction.
*Characteristics:
* Splitting: Normally slightly split (~0.04 seconds) because the mitral valve
closes slightly before the tricuspid valve. This split is usually too short to
be heard with a stethoscope, so S1 is perceived as a single sound.
Describe all the characteristics to do with the S2 heartbeat sound
*Cause: Closure of the aortic and pulmonic valves.
*Timing: Occurs at the beginning of isovolumetric ventricular relaxation.
*Characteristics:
* Splitting: Physiologically split because the aortic valve closes slightly
before the pulmonic valve.
* Variability: The duration of S2 splitting changes depending on respiration,
body posture, and certain pathological conditions. For instance, the split
widens during inspiration and narrows during expiration
