Cardiac Cycle Flashcards
What are the anatomical structures involved in cardiac pump function?
Ventricular walls
Heart valves
Chordae Tendinea
Papillary muscles
Pericardium
Sarcomeres
Where will you find the lowest pressure in teh body?
Right atrium
(also known as central venous pressure)
The atria have how many layers of muscle?
2 layers
each are perpendicular to one another
The ventricles have how many layers?
3 layers
( 2 perpendicular, one diagonal)
How does right ventricular ejection occur?
- Shortening of the free wall
- compression of the chamber (Bellows Action)
How does left ventricular ejection occur?
- Constriction of chamber
- Shortening of Chamber
- Traction on Right ventricular wall
What occurs when you have ventricular pressure?
The AV valves close
What occurs when you have high atrial pressure?
The AV valves open
Since the valves are made of connective tissue, what type of opening do they do?
The valves passivly open when there is a pressure difference
What the requirements for effective cardiac pumping (effective efficient ventricular pumping action)?
- The contractions of individual cardiac muscle cells must occur at regular intervals and be synchronized.
- The valves must open fully
- The valves must not leak
- The muscle contractions must be forceful
- The ventricles must fill adequately during diastole
what is the cardiac cycle?
The period of time from the beginning of one ventricular contraction to the beginning of the next
What are the two phases that are part of the cardiac cycle?
- Systole: contraction of the ventricle
- closure of the A-V valves -> closure of the Semilunar valves
- 1/3rd of the cycle
- Diastole: the period of ventricular relaxation
- closure of the semilunar valve -> closure of the A-V valve
- 2/3rd of the cycle
There are two phases of systole, what are they?
Isovolumic contraction
Ejection period
There are two stages in diastole, what are they?
Isovolumic relaxation
Filling period
What occurs during Isovolumic Contraction Period?
- ventricles generate pressure (by slow contraction) without expulsion of blood volume (increase in pressure causes AV valves to close)
- Bothe A-V valve and semilunar valves are closed (closed chamber)
This is also known as Ventricular Systole
Atria are relaxed
What occurs during the ejection period?
- the A-V valves are closed and semilunar valves have opened up (this is because the pressure in the ventricle is now higher than the pressure in the aorta/pulmonary trunk)
- Rapid ejection: 70% of total ejection volume is expelled during the 1st 1/3 of the ejection period
- Reduced Ejection: the remaining 30% of the ejected volume occurs during the last 2/3 of the ejection period.
What occurs during Isovolumic relaxation?
- The ventricular chamber volume remains constant but the chamber pressure drops
- Both A-V and Semilunar Valves are closed
Ventricles are relaxed
Dicrotic Notch occurs during this phase