BSI 2 Lecture 14-15: Cardiac Cycle Flashcards
What is the function of the atria?
To shuttle blood to the ventricle
What happens to 60-90% of the blood when the AV valves are open?
They pass straight through to the ventricles
What happens when the atria contract?
They push more blood into the ventricles (10-40%)
What happens when atria enhance the amount of blood in ventricles?
They enhance ventricular pumping
What is the function of the right ventricle?
To pump blood through pulmonary circulation
What is the function of the left ventricle?
To pump blood through systemic circulation
Do valves open passively or actively?
Passively
What opens valves?
Foward pressure
What closes valves?
Backwards pressure
Which valves have chordae tendinae and papillary muscle?
Atrioventricular valves
What are the steps of the cardiac cycle?
1) atrial contraction
2) isovolumetric contraction
3) ejection
4) isovolumetric relaxation
5) ventricular filling
What is systole?
contraction phase
What is diastole?
Relaxation phase
What is pulse pressure?
Systolic BP - Diastolic BP
What is end diastolic volume?
the amount of blood in the ventricle once it is filled just before it contracts
What is an important determinant of EDV?
Venous return
What is end systolic volume (ESV)?
The volume of blood in the ventricle at the end of systole
What is stroke volume?
The volume of blood pumped out of the ventricle per contraction
What determines stroke volume?
preload, afterload, and contractility
What is ejection fraction?
The fraction of EDV that was pumped out of the left ventricle per contraction. SV/EDV * 100
What is cardiac output?
The amount of blood pumped out of the left ventricle per minute. (heart rate * SV) = CO
What is venous return?
The amount of blood returned to the heart
What is preload?
It is the stretch of the heart before contraction. It is mainly affected by end diastolic volume. The great the preload, the greater the contractility.
What is afterload?
The amount of pressure the ventricles have to overcome to pump blood out of the heart. If pulmonary pressure or aortic pressure is higher than the pressure of the ventricles, they will have an increased afterload.
What is contractility?
The intrinsic ability of cardiac muscle to produce tension, independent of fiber (sarcomere) length
What is the primary determinant of contractility?
Intracellular calcium
What is a chronotropic effect?
Anything effecting heart rate
What is an ionotropic effect?
Anything affecting heart contractility
What is cardiac reserve?
the work that the heart is able to perform beyond that required of it under basal/resting conditions
What is Pressure-Rate product?
An indirect index of myocardial O2 consumption (how hard the ventricle is working). HR x SBP (or MAP)
What are the heart sounds?
Sound 1: closing of AV valves. Sound 2: closing of semilunar valves
