Cardiovascular System
What feature distinguishes pacemaker cardiac cells from other myocardial cells? Pacemaker cells:
Require a stimulus from the vagus nerve in order to reach threshold; myo-cardial cells do not.
Reach threshold with much weaker stimuli than myocardial cells.
Have gap junctions, while myocardial cells do not.
Spontaneously generate action potentials, while myocardial cells do not.
Spontaneously generate action potentials, while myocardial cells do not.
Pacemaker cells (generally in the SA node) generate action potentials 80โ100 times per minute even without neural input. Neural input will slow or increase this rate. Myocardial cells are not autorhythmic.
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By what name is the heart muscle known?A. Epicardium
B. Myocardium
C. Pericardium
D. Endocardium
Which statement about cardiac output is correct?
A. Cardiac output is peripheral resistance multiplied by stroke volume.
B. Mean arterial pressure multiplied by peripheral resistance is cardiac output.
C. Cardiac output is heart rate multiplied by stroke volume.
D. Cardiac output is blood volume multiplied by heart rate.
What is “systolic pressure”?
A. The peak pressure in the blood due to contraction of the left ventricle.
B. The minimum pressure in the blood prior to contraction of the left ventricle.
C. It may be obtained by multiplying cardiac output by total peripheral resistance.
D. It is also known as mean arterial pressure.
A statement of Boyle’s law could be:
A. As pressure of a gas increases, its solubility increases.
B. As volume of a gas increases, its pressure decreases.
C. As volume of a gas decreases, its pressure decreases.
D. As pressure of a gas increases, its solubility decreases.
Which of the following is not a type of white blood cell?
A. Leucocyte
B. Eosinophil
C. Erythrocyte
D. Neutrophil
Consider Boyle’s law. If the pressure being exerted on an enclosed volume of gas (at a constant temperature) is increased by 20%, by what percentage would its volume change?
A. Volume would increase by 20%.
B. Volume would increase by 44%.
C. Volume would decrease by 44%.
D. Volume would decrease by 20%.
Through which valve does blood flow when it moves from the left atrium into the left ventricle?
A. The semilunar valve
B. The mitral valve
C. The tricuspid valve
D. The aortic valve
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