1. When a papillary muscle in the left ventricle ruptures, the mitral valve
leaflets do not close completely, resulting in which condition?
A. acute myocardial infarction.
B. aortic valve failure.
C. cardiac murmur.
D. systemic venous congestion <Ans> Cardiac murmur
A dysfunction of the chordae tendineae or of a papillary muscle can cause incom-
plete closure of an atrioventricular valve, which results in backflow of blood into the
atrium and produces a murmur. If a papillary muscle in the left ventricle ruptures,
the mitral valve leaflets do not close completely. Clinically, this causes acute mitral
regurgitation and an audible murmur that can be auscultated with a stethoscope.
2. Aortic valve dysfunction pathologically alters which structure of the heart?
A. left atrium.
B. left ventricle.
C. right ventricle.
D. mitral valve <Ans> Left ventricle
Aortic valve dysfunction from any cause not only affects the valve leaflets but also
pathologically alters the shape of the left ventricle.
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, 3. A physiologic cardiac shunt occurs when there is mixing of deoxygenated blood
(usually venous blood with reduced oxygen content) with arterial oxy- genated
blood. In the heart, this is demonstrated by which mechanism?
A. atrial septal defect.
B. patent foramen ovale.
C. thebesian veins.
D. ventricular septal defect <Ans> Thebesian veins
The thebesian veins are small vessels that connect capillary beds directly with the
cardiac chambers via irregular endothelium-lined sinuses within the myocardium.
The thebesian veins add a small quantity of deoxygenated blood to the oxygenated
blood in the left ventricle.
4. The time from the beginning of the cardiac action potential (AP) until the time
when the fiber can accept another AP is known as which period?
A. excitability
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