Practice Test 1 Flashcards
Inflammatory pathways promote thrombosis, which is responsible for myocardial infarction and most strokes.
True
What is released from the endothelial wall, that promotes vasodilatation and limits platelet extension?
prostacyclin (PG12)
A traumatized vessel will constrict; most of the constriction is due to which of the following?
local myogenic spasm
Which of the following is effective at dissolving blood clots?
plasmin
What is the key step in blood coagulation?
the conversion of fibrinogen to fibrin
Fibrinogen and prothrombin along with factors VII, IX, X are produced by which organ?
liver
Concerning Ca++ role in blood clotting, which of the following statements is true?
required at all steps except the 1st two intrinsic steps
Compared to a typical ventricular muscle cell, which of the following is a characteristic of the SA node?
lacks a stable resting polarized state
At a normal resting membrane potential of -85 mV, which of the following ions is closest to its Nernst equilibrium potential?
K+
A 2-3 X elevation in extracellular fluid of what ion can cause flaccidity and weakness of cardiac muscle in part by decreasing the resting membrane potential.
K+
If end diastolic volume = 160 ml and end systolic volume = 120 ml; what is the ejection fraction?
25%
What allows the action potential to spread from one cardiac cell to an adjacent cardiac cell, and therefore allows the heart to behave as a syncytium?
intercalated discs
Which of the following create only a diastolic murmur?
mitral stenosis
Reperfusion injury following infarction is primarily associated with which of the following?
free radical production
Which of the following changes in ion flux will slow the heart rate?
increase in K+ efflux
What is the major function of the AV node?
delays the wave of depolarization from the atria to the ventricle
An inverted T wave is associated with which of the following?
ischemia
Most of the energy consumed by the heart for work is utilized for which of the following?
pressurization of blood by the ventricles
As heart rate increases, cycle length decreases, which of the following statements is true?
diastole shortens more than systole
If you block fast Na+ channels in a typical cardiac muscle cell using “tetradotoxin”, what will be observed?
depolarization is slowed
No consistent relationship of P waves to QRS complexes describes which of the following?
3rd degree AV block
At a constant operating pressure what happens to the wall tension as the radius of that chamber decreases?
decreases
The preferred energy substrate of ventricular cardiac cells is which of the following?
FA
Under resting conditions, what percentage of oxygen is extracted by the myocardium from the perfusing coronary blood flow?
70%
If the sympathetic nerves to the heart are cut, and then the SNS is stimulated, heart rate will
still increase, why?
circulating norepinephrine/epinephrine from the adrenal medulla
Which of the following statements regarding a prolonged QT interval (increased incidence of sudden cardiac death) is true?
males are more susceptible than females
If the left atrial pressure is 7 mmHg., the left ventricular pressure is 100 mmHg., and the aortic blood pressure is 106 mmHg., what is the status of the valves on that side of the heart?
mitral and aortic valves closed
Increased stretch on the ventricular fibers during filling, have what effect on calcium influx into the ventricular cells?
increase
Which of the following has a positive inotropic effect on the ventricle.
acetylcholine
A wave of repolarization moving toward the positive recording electrode would create what type of deflection?
negative deflection
When does myocardial blood flow peak in the left ventricle?
at the onset of diastole
What percentage of blood from the atrial to the ventricle is actively pumped?
25-30%
Norepinephrine binds to which cardiac receptors?
beta
At rest, if you block both divisions of the autonomic nervous system, what changes will occur?
HR will increase and strength of contraction will decrease
Which has a positive inotropic effect on the ventricle?
thyroxine
