BMEG302 FINAL EXAM REVIEW - ALL
QUIZ QUESTIONS AND ANSWERS
Why is the left ventricle of the heart referred to as the "center of the universe" in
cardiology?
The left ventricle of the heart is called the "center of the universe" in cardiology because
it is the larger and more powerful of the pumping chambers of the heart. It needs to be
bigger because its function is to send blood out to perfuse to the whole body, as
opposed to just the short trip to the lungs that the right ventricle is responsible for.
Additionally, almost all cardiac deficits/pathologies that appear clinically have their roots
in the pumping of the left ventricle, if it fails, we die.
What outcome do you get when you subtract the volume value of the lower left
point (D) of the cardiac P-V curve loop from the volume of the lower right point
(A)?
The stroke volume, Vstroke.
Within the cardiac P-V curve, the cardiac cycle loop moves in which direction?
Counterclockwise
If P(LV) < P(LA), which of the following indicated the way that the blood in the
heart would want to flow?
From left atrium to left ventricle
If a patient presents with A-fib, in which part of their heart do they likely have a
deficit?
SA node
What type (or class) of drug increases heart rate?
positive chronotropic drugs
adrenaline
epinephrine
In our linear model of the cardiac cycle, what variable changes when we
exercise?
V(ED) - When we exercise, we increase our venous pressure through a combination of
the skeletal muscle and respiratory pumps. This increases the end diastolic volume of
the ventricle because there is a larger filling pressure.
Which of the following conditions would result in the heart doing less work
during a single cardiac cycle?
Administering a negative inotropic drug - this would reduce cardiac output by reducing
stroke volume, but not necessarily altering pressures. It does so by decreasing
contractility and therefore increasing systolic compliance.
Why is cardiac compliance (C) less in systole than diastole (Csys << Cdia)?
Cardiac compliance is less during systole than diastole because the contracted heart
muscle is more stiff, thus less compliant than relaxed heart muscle (during diastole). As
cardiac muscle contracts, it becomes stiffer, and as it relaxes it becomes 'softer'.
What are our assumptions when modeling fluid flow within a compliance vessel?
1. That there is no flow into, out of, or through the vessel (Q1 = Q2 = 0)
, 2. Pressures within the vessel are all identical. At all locations in the vessel the pressure
is constant. This has to be true for assumption 1 to be true.
Does stimulation of the heart by the vagus nerve increase or decrease heart rate?
Decrease - the vagus nerve, as part of the parasympathetic nervous system, tonically
inhibits HR. Therefore, elevating vagus nerve activity will further inhibit HR.
A balloon is an example of a resistance vessel.
False
Heart chambers and blood vessels can act as resistance vessels or compliance
vessels.
True - They can act, and be modeled as either, depending on the circumstances.
What are the names of the curves that contain/restrict the P-V loop for the heart?
Envelope curves
Cardiomyocytes are grouped into bundles which are embedded within a
predominantly fibronectin matrix.
False - The extracellular matric (ECM) that surrounds the interconnected bundles of
cardiomyocytes is predominantly composed of collagen.
When working with an equation that has the general form of an exponential
function, the time constant tau affects the shape of the curve. What percentage of
the response is accounted for when time (t) = tau?
63.2%
If a person is experiencing severe tachycardia and is unable to compensate for
this, how does their Vstroke change?
It decreases - severe tachycardia is highly elevated heart rate, >> 100 bpm. In this
case, the amount of time reserved in each cardiac cycle for the ventricle to fill, diastole,
is reduced a lot. If the ventricle cannot fill as much, V(ED) decreases, and the stroke
volume decreases.
What equation would you use to convert force to stress?
stress (sigma) = F/A --> F = force, A = area
When modeling the filling rate of the ventricle, what assumption(s) about the AV
valve is true?
The valve can be modeled as a rigid pipe - There are two states to the AV (mitral) valve
during the cardiac cycle. The valve is open during filling (diastole) and closed during
systole. The transition from open to closed represents a change in resistance, from low
resistance (open) to infinite resistance (closed), so the resistance does change. The
resistance of the valve is a function of the radius of the valve opening, it does not
depend upon V(0). In our model the valve is modeled as a rigid pipe, not as a compliant
tube; the ventricles are the compliant vessels.
If you increase the diameter of the pipe, how much does resistance change?
If you increase the diameter of the pipe, the resistance will decrease as a function of
r^4.
Uncontrolled circulation provides sufficient control of blood flow to meet the
needs of the body during strenuous activity.
False - Uncontrolled circulation is insufficient to generate enough cardiac output (Q) to
meet the necessary demands associated with strenuous activity, like exercise. The only
variable that is explicitly modifiable in the uncontrolled circulation model is systemic
resistance, due to the ability to alter the diameter of the arterioles. However, even 90%
QUIZ QUESTIONS AND ANSWERS
Why is the left ventricle of the heart referred to as the "center of the universe" in
cardiology?
The left ventricle of the heart is called the "center of the universe" in cardiology because
it is the larger and more powerful of the pumping chambers of the heart. It needs to be
bigger because its function is to send blood out to perfuse to the whole body, as
opposed to just the short trip to the lungs that the right ventricle is responsible for.
Additionally, almost all cardiac deficits/pathologies that appear clinically have their roots
in the pumping of the left ventricle, if it fails, we die.
What outcome do you get when you subtract the volume value of the lower left
point (D) of the cardiac P-V curve loop from the volume of the lower right point
(A)?
The stroke volume, Vstroke.
Within the cardiac P-V curve, the cardiac cycle loop moves in which direction?
Counterclockwise
If P(LV) < P(LA), which of the following indicated the way that the blood in the
heart would want to flow?
From left atrium to left ventricle
If a patient presents with A-fib, in which part of their heart do they likely have a
deficit?
SA node
What type (or class) of drug increases heart rate?
positive chronotropic drugs
adrenaline
epinephrine
In our linear model of the cardiac cycle, what variable changes when we
exercise?
V(ED) - When we exercise, we increase our venous pressure through a combination of
the skeletal muscle and respiratory pumps. This increases the end diastolic volume of
the ventricle because there is a larger filling pressure.
Which of the following conditions would result in the heart doing less work
during a single cardiac cycle?
Administering a negative inotropic drug - this would reduce cardiac output by reducing
stroke volume, but not necessarily altering pressures. It does so by decreasing
contractility and therefore increasing systolic compliance.
Why is cardiac compliance (C) less in systole than diastole (Csys << Cdia)?
Cardiac compliance is less during systole than diastole because the contracted heart
muscle is more stiff, thus less compliant than relaxed heart muscle (during diastole). As
cardiac muscle contracts, it becomes stiffer, and as it relaxes it becomes 'softer'.
What are our assumptions when modeling fluid flow within a compliance vessel?
1. That there is no flow into, out of, or through the vessel (Q1 = Q2 = 0)
, 2. Pressures within the vessel are all identical. At all locations in the vessel the pressure
is constant. This has to be true for assumption 1 to be true.
Does stimulation of the heart by the vagus nerve increase or decrease heart rate?
Decrease - the vagus nerve, as part of the parasympathetic nervous system, tonically
inhibits HR. Therefore, elevating vagus nerve activity will further inhibit HR.
A balloon is an example of a resistance vessel.
False
Heart chambers and blood vessels can act as resistance vessels or compliance
vessels.
True - They can act, and be modeled as either, depending on the circumstances.
What are the names of the curves that contain/restrict the P-V loop for the heart?
Envelope curves
Cardiomyocytes are grouped into bundles which are embedded within a
predominantly fibronectin matrix.
False - The extracellular matric (ECM) that surrounds the interconnected bundles of
cardiomyocytes is predominantly composed of collagen.
When working with an equation that has the general form of an exponential
function, the time constant tau affects the shape of the curve. What percentage of
the response is accounted for when time (t) = tau?
63.2%
If a person is experiencing severe tachycardia and is unable to compensate for
this, how does their Vstroke change?
It decreases - severe tachycardia is highly elevated heart rate, >> 100 bpm. In this
case, the amount of time reserved in each cardiac cycle for the ventricle to fill, diastole,
is reduced a lot. If the ventricle cannot fill as much, V(ED) decreases, and the stroke
volume decreases.
What equation would you use to convert force to stress?
stress (sigma) = F/A --> F = force, A = area
When modeling the filling rate of the ventricle, what assumption(s) about the AV
valve is true?
The valve can be modeled as a rigid pipe - There are two states to the AV (mitral) valve
during the cardiac cycle. The valve is open during filling (diastole) and closed during
systole. The transition from open to closed represents a change in resistance, from low
resistance (open) to infinite resistance (closed), so the resistance does change. The
resistance of the valve is a function of the radius of the valve opening, it does not
depend upon V(0). In our model the valve is modeled as a rigid pipe, not as a compliant
tube; the ventricles are the compliant vessels.
If you increase the diameter of the pipe, how much does resistance change?
If you increase the diameter of the pipe, the resistance will decrease as a function of
r^4.
Uncontrolled circulation provides sufficient control of blood flow to meet the
needs of the body during strenuous activity.
False - Uncontrolled circulation is insufficient to generate enough cardiac output (Q) to
meet the necessary demands associated with strenuous activity, like exercise. The only
variable that is explicitly modifiable in the uncontrolled circulation model is systemic
resistance, due to the ability to alter the diameter of the arterioles. However, even 90%
