Which Of The Following Would Increase Cardiac Output
Question: At what rate does the sinoatrial (SA) node depolarize?
30 times per minute
40 times per minute
50 times per minute
75 times per minute
Answer: 75 times per minute
The sinoatrial node typically depolarizes spontaneously about 75 times per minute, although this can vary in different individuals. This rate is directly modulated by the autonomic nervous system.
Question: Which of the following increases stroke volume?
decrease in end diastolic volume (EDV)
severe blood loss
decrease in preload
exercise
Answer: exercise
Exercise increases venous return, which would in turn increase the amount of blood in the presystolic ventricle (preload).
Question: Which of the following would cause a DECREASE in cardiac output (CO)?
decreasing thyroid function (thyroxine)
suddenly standing up from a supine position
an increase in adrenal medulla output (epinephrine)
heightened use of skeletal muscle
Answer: decreasing thyroid function (thyroxine)
Thyroxine increases basal metabolic rate, respiratory rate, and both heart rate and contractility.
Question: The __________ valve is located between the right atrium and the right ventricle.
mitral
aortic semilunar
pulmonary semilunar
tricuspid
Answer: tricuspid
The tricuspid valve is located between the right atrium and right ventricle.
Question: What structures connect the individual heart muscle cells?
intercalated discs
trabaculae carneae
chordae tendineae
anastomoses
Answer: intercalated discs
Intercalated discs connect the heart muscle cells. They include desmosomes (anchoring junctions) and gap junctions (communicating junctions).
Question: Which portion of the electrocardiogram represents the depolarization wave received by the atria from the sinoatrial (SA) node?
S-T segment
P wave
QRS complex
T wave
Answer: P wave
The P wave represents the depolarization of the left and right atria and the beginning of atrial systole.
Question: The first heart sound (the “lub” of the “lub-dup”) is caused by __________.
atrial contraction
closure of the semilunar valves
closure of the atrioventricular valves
ventricular contraction
Answer: closure of the atrioventricular valves
The first heart sound (the “lub” of the “lub-dup”) is generated by the closure of the atrioventricular valves
Question:
Answer: Gap junctions allow action potentials to spread to
connected cells.
Gap junctions are a form of electrical synapse that allow action potentials to spread to connected cells. This property allows the signal to spread efficiently through the heart.
Question: Which of the following would increase cardiac output?
parasympathetic stimulation
decreased calcium during contraction
high blood pressure
epinephrine
Answer: epinephrine
Sympathetic stimulation leads to the release of epinephrine and norepinephrine, both of which increase heart rate and increase contractility, which increases stroke volume. Increasing heart rate and stroke volume increases cardiac output.
Question: Which of the following does NOT deliver deoxygenated blood to the heart?
coronary sinus
pulmonary veins
superior vena cava
inferior vena cava
Answer: inferior vena cava
The pulmonary veins deliver oxygenated blood to the left atrium.