This is yet another stem of questions using the laws of flow physiology to elucidate the means of heart failure and compensation for different volume-ion changes in disease states. Enjoy! 

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Control of Cardiac Output

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Question 1
The volume of blood present in the ventricles at the end of each cardiac cycle is approximately how many millilitres?
A
100
B
120
C
140
D
160
Question 2
How is ejection fraction calculated?
A
SV/ESV
B
CO/EDV
C
SV/EDV
D
CO/ESV
Question 3
A Hartmann fluid bolus challenge to a patient in shock does what to the stroke volume of the patient directly?
A
Increases contractility
B
Increases inotropy
C
Increases adrenergic response
D
Increases preload
Question 3 Explanation: 
The direct effect is preload increase. This causes a great many things, such as atrial stretch reflex to trigger natriuresis and a greater contractile force to push additional volume.
Question 4
By a powerful increase in TPR (SVR), the body's autonomous response to hypovolaemia affects stroke volume in which way described below?
A
A decrease in preload
B
An increase in the contractility of the heart
C
An increase in afterload
D
A decrease in volume of the chamber
Question 5
CO = ____ x HR
A
EF
B
SV
C
EDV
D
ESV
Question 6
Which of the following is not true of the Bainbridge atrial stretch reflex?
A
it utilises mechanoceptors
B
It transmits afferents to the medulla via the tenth cranial nerve
C
An increase in cholinergic efferents results
D
An increase in noradrenergic efferents results
Question 6 Explanation: 
The sympathetic nervous system is up-regulated in the atrial stretch reflex. Thus, concomitantly, the parasympathetics are down-regulated. The former utilises noradrenergic efferents, the latter the cholinergics.
Question 7
Serum pH is tightly controlled to ensure adequate perfusion of tissues.  Which of the following are not related to chemoreception and its homeostasis?
A
Vagus nerve
B
Glossopharyngeal nerve
C
Medulla
D
Carotid sinus
Question 7 Explanation: 
The carotid body - not the carotid sinus - is involved in chemoregulation. The carotid sinus role is baroreception.
Question 8
What is the most powerful way to increase a patient's stroke volume?
A
Increase contractility
B
Increase inotropy
C
Increase preload
D
Decrease afterload
Question 9
Which of the following scenarios increase afterload?
A
Increase of venous compliance
B
Hypertrophic cardiomyopathy
C
An increase of cardioaccelerator nerve functionality
D
Increasing aortic arch pressure
Question 10

Stem 1 of 4

A patient is recovering after a myocardial infarction. Under LaPlace and Starling's law his heart must necessarily work greater and the cardiologist cautions the patient is at risk of hypertrophic cardiomyopathy.
Under Starling's law, what is EDV proportional to?
A
TPR
B
SVR
C
Afterload
D
Contractility
Question 11

Stem 2 of 4

In the short term, which of the below scenarios is the patient's myocardium less likely to undergo?
A
Increases cardioaccelerator sympathetic postganglionics
B
Increased myocardial contracture force
C
Remodelling of the heart chamber
D
Increase of the HR
Question 11 Explanation: 
This is an example of the longer-term consequence when the patient's heart is insufficiently able to deal with an increase of EDV and thus undergoes dilatation.
Question 12

Stem 3 of 4

Sarcomere length, ergo Starling's law of contracture, is determined by ...
A
SVR
B
TPR
C
ESV
D
EDV
Question 13

Stem 4 of 4

The patient had an infarct to the artery determining coronary dominance during his MI. How would you classify this vessel functionally?
A
Exchange
B
Resistance
C
Distributive
D
Capacitance
Question 13 Explanation: 
PIVA, or the posterior inter ventricular branch of the coronary arteries, determine coronary artery dominance. As such, the question is asking for the classification of an artery -which is a distributive vessel.
Question 14
A patient with severe dehydration would see what change to their cardiac physiology based on Frank-Starling's law?
A
An increase in systemic vascular resistance
B
A decrease in myocardial contractility
C
A decrease in the capacitance vasomotor activity
D
An increase in the vasodilation of the caval circulation
Question 14 Explanation: 
FS law states that contractility is directly proportional to EDV. In the dehydrated patient, volume decrease leads - in extremis - to a decrease of stretch on the sarcomere, thus a decrease in the power provided from the sliding filament theory.
Question 15
In HFrEF, what is the positive feedback loop that proves ultimately fatal?
A
Increase to CO increases EDV
B
Increase to CO decreases EDV
C
Decrease to CO increases EDV
D
Decrease to CO decreases EDV
Question 15 Explanation: 
There is a decreased pump action of the heart, leading to reduced CO. This causes an increase of EDV, which Frank Starling can compensate for, but only for a time before dilation occurs and the heart muscle undergoes permanent death.
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