The SA node is the normal pacemaker of the human heart because its cells
1. spontaneously generate electrical signals about 70 to 80 times per minute.
2. are located in the interventricular septum.
3. generate electrical signals only when stimulated by sympathetic fibers.
4. are not in contact with other cells of the heart.

Subtopic:  Human Heart: Cardiac Cycle |
 86%

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If the SA node is not functional in a human being, his ECG would not show:
1. P wave
2. QRS complex
3. ST segment
4. T wave

Subtopic:  ECG & Coronary Artery Disease |
 69%
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What causes the opening of tricuspid and bicuspid valves?
1. Atrial pressure greater than pressure in the ventricles.
2. Ventricular pressure greater than pressure in the arteries.
3. Arterial pressure greater than pressure in the ventricles.
4. Ventricular pressure greater than pressure in the atria.

Subtopic:  Human Heart: Cardiac Cycle |
 74%

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What happens during the isovolumetric relaxation of the cardiac cycle?
1. the atria contract and pump blood into the ventricles.
2. the ventricles contract and pump blood into the blood vessels.
3. both atria and ventricles are relaxed.
4. the ventricles contract but ventricular pressure is lower than arterial. pressure

Subtopic:  Human Heart: Cardiac Cycle |
 65%

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The semilunar valves close at the beginning of

1. atrial systole 2. atrial diastole
3. ventricular systole 4. ventricular diastole
Subtopic:  Human Heart: Cardiac Cycle |
 56%

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How would the blood pumped per minute by the left ventricle compare with that pumped by the right ventricle?
1. normally greater than that of the right ventricle.
2. probably lower than the right ventricle if the person has systemic edema.
3. probably lower than the right ventricle if the person has pulmonary edema.
4. probably higher than the right ventricle if the person has pulmonary edema.

Subtopic:  Human Heart: Cardiac Cycle |

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Under normal physiological conditions a higher cardiac output can be achieved by a higher:
1. extracellular K+ concentration
2. blood pressure in the systemic circulation
3. venous return
4. parasympathetic tone

Subtopic:  Human Heart: Cardiac Cycle |

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Vagotomy [cutting of vagus nerve] would lead to:
1. reduced heart rate
2. increased heart rate
3. reduced strength of contraction
4. increased secretion of acetylcholine

Subtopic:  Regulation of Cardiac Activity |

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The cardiovascular system is located in:
1. cerebral cortex
2. thalamus
3. basal nuclei
4. medulla oblongata

Subtopic:  Regulation of Cardiac Activity |
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The liquid portion of the blood with fibrinogen and some of the clotting proteins removed is
1. plasma.
2. platelets.
3. plasma proteins.
4. serum

Subtopic:  Blood: General Description & RBC |
 76%

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