Lecture 3: Study Guide For Quiz Flashcards
The cardiac cycle has how many phases?
7 phases
Phase 1 =
Atrial systole
Phase 2 =
Isovolumic contraction
Phase 3 =
Rapid ejection
Phase 4 =
Reduced ejection
Phase 5 =
Isovolumic relaxation
Phase 6 =
Rapid filling
Phase 7 =
Diastasis
What phases are part of ventricular systole?
Phase 2: isovolumic contraction
Phase 3: rapid ejection
Phase 4: reduced ejection
What phases are part of ventricular diastole?
Phase 5: isovolumic relaxation
Phase 6: rapid filling
Phase 7: diastasis
Phase 1: atrial systole
During what phase does most of ventricular filling occur?
Phase 6–rapid ventricular filling
Does opening or closing of healthy heart valves create heart sounds?
Closing
The incisura or dicrotic notch of the aortic pressure tracing marks the beginning of what?
The beginning of ventricular systole
What valve closes at the dicrotic notch?
Aortic valve
During what phases of the cardiac cycle are the mitral and aortic valves both closed?
Phase 2: isovolumic contraction (ventricular systole)
Phase 5: isovolumic relaxation (ventricular diastole)
Name the various waves of the CVP.
- A wave
- C wave
- V wave
- X descent
- Y descent
CVP—A wave
- End diastole
- Atrial contraction
CVP—C wave
- Early systole
- Ventricular filling
CVP—V wave
- Late systole
- Atrial filling from ventricular systole
CVP—X descent
- Mid systole
- Atrial relaxation
CVP—Y descent
- Early diastole
- Ventricular filling
The first heart sound signifies closure of which heart valves?
Closure of mitral/tricuspid (AV) valves during isovolumic contraction (phase 2)
The second heart sound signifies closure of which heart valves?
Closure of aortic/pulmonic valves during isovolumic relaxation (phase 5)
During which phase of the cardiac cycle is the majority of blood ejected from the left ventricle?
Phase 3–rapid ejection
During which phase of the cardiac cycle does most of the filling of the left ventricle occur?
Phase 6–rapid ventricular filling
What is the “atrial kick”?
Occurs near the end of diastole as the atria begin contracting and pump blood into the ventricles—this pressurized delivery during ventricular relaxation (ventricular diastole) is called the atrial systole or atrial kick
How much does the atrial “kick” contribute to ventricular filling? Does it vary with different rhythms?
At normal heart rates, 10%
At higher heart rates (i.e.: during exercise), can contribute up to 40% of ventricular filling.
There can be a loss of atrial kick in patients with atrial fibrillation.
What are the 4 major determinants of cardiac output?
- Preload
- Afterload
- Contractility
- Heart rate
Under normal circumstances, stroke volume can be INCREASED by increasing or decreasing end-diastolic volume (no change in ESV)?
Increasing EDV
Under normal circumstances, stroke volume can be INCREASED by increasing or decreasing end-systolic volume (no change in EDV)?
Decreasing ESV
What is the Bowditch Effect/Treppe Effect/Staircase Phenomenon?
The idea that an increase in heart rate will also cause positive inotropy
What are other names for the Bowditch Effect?
- Treppe Effect
- Staircase Phenomenon
What causes the Bowditch Effect?
- It occurs due to an increase in intracellular Ca++ with higher heart rates
- More Ca++ = more depolarizations per minute
- Na+/K+-ATPase pump cannot keep up with the influx of Na+, thus the Na+-Ca++ exchange pump doesn’t function as well
Why do extremely high heart rates result in a decrease in cardiac output?
The heart at a faster rate does not stay relaxed long enough to allow for complete ventricular filling
As preload increases (within normal limits), cardiac output increases. What is the name for this phenomenon?
Frank-Starling Mechanism
As preload decreases, cardiac output decreases. What is the name for this phenomenon?
Frank-Starling Mechanism
What physiologic relationship keeps cardiac output of the ventricle matched with venous return?
Frank-Starling Mechanism
What physiologic relationship keeps the cardiac output of the right and left ventricles matched?
Frank-Starling Mechanism
What are some of the things that affect ventricular preload? (6 things)
- Venous blood pressure (affected by venomotor tone/venous volume)
- Filling time
- Ventricular compliance
- Atrial contraction
- Inflow or outflow resistance
- Ventricular systolic failure
What affects venous volume? (5 things)
- Venous return
- Total blood volume
- Respiration
- Exercise/muscle contraction
- Gravity
What is the Frank-Starling Relationship?
When venous return to the heart is increased, ventricular filling increases, as does preload. This stretching of the myocytes causes an increase in force generation, which enables the heart to eject the additional venous return and thereby increase stroke volume.
AKA—the heart pumps the blood that returns to it
The Frank-Starling Relationship allows the heart to readily adapt to changes in ___
Venous return
The Frank-Starling Relationship plays an important role in balancing…
The output of the 2 ventricles
(According to the Frank-Starling Relationship) Increasing ___ and ___ leads to an increase in ___
Venous return and ventricular preload, stroke volume
What parameter is representing on the “y” axis (vertical axis) of the Frank-Starling Curve?
Stroke volume
What parameter is represented on the “x” axis (horizontal axis) of the Starling Curve?
Left ventricular end diastolic pressure (LVEDP)
What factors can cause an increased afterload? (4 things)
- Increased aortic pressure
- Increased systemic vascular resistance
- Aortic valve stenosis
- Ventricular dilation
Increases in afterload cause cardiac output to increase or decrease?
Decrease
Wall stress can be used to help understand what determinant of cardiac output?
Afterload
Define contractility.
The inherent capacity of the myocardium to contract independently of changes in afterload or preload
What is another name for contractility?
Inotropy
