Cardiovascular System
Blood may flow in the aorta with a speed of 30 cm/s and in the capillaries with a speed of only 0.1 m/s. Why is there such a large difference in speed?
The capillaries are much further from the heart than the aorta.
The very narrow capillaries present a large resistance to blood flow com-pared to the large diameter aorta.
The total cross-sectional area of the lumens of the capillaries is much greater than the cross-sectional area of the aorta.
The length of the aorta is short compared to the length of a capillary.
The total cross-sectional area of the lumens of the capillaries is much greater than the cross-sectional area of the aorta.
The “equation of continuity” may be stated: volume flow rate = cross- sectional area ร speed of flow. Hence if the total cross-sectional area of capillaries is very large (as it is), the speed of flow can be very slow while still allowing the required volume flow rate.
The total cross-sectional area of the lumens of the capillaries is much greater than the cross-sectional area of the aorta. The “equation of continuity” may be stated: volume flow rate = cross- sectional area ร speed of flow. Hence if the total cross-sectional area of capillaries is very large (as it is), the speed of flow can be very slow while still allowing the required volume flow rate.
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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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