Cardiovascular System
People with occupations that involve standing all day are at risk of varicose veins. Why should this be true?
Veins have a larger lumen than arteries and so hold more blood which distends them.
Veins have only two tunics so their walls are more easily stretched into varicosity.
Gravity acting on blood in the legs puts stress on the vessel walls increasing the likelihood that they will stretch and distort.
When standing still, the valves stay open and blood accumulates in the leg veins.
Gravity acting on blood in the legs puts stress on the vessel walls increasing the likelihood that they will stretch and distort.
Gravity acting on the blood in the legs of a standing person increases the strain on the walls of a vein. A weakness will lead to the walls becoming distended and the valve not operating correctly.
Gravity acting on blood in the legs puts stress on the vessel walls increasing the likelihood that they will stretch and distort. Gravity acting on the blood in the legs of a standing person increases the strain on the walls of a vein. A weakness will lead to the walls becoming distended and the valve not operating correctly.
Related posts
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
Leave a Reply