pulse

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pulse

Postby BO on November 23rd, 2005, 1:24 am 

This may be a dumb question but.. why can you feel your pulse in arteries but not in veins? If there's no pulse in your veins, what pushes the blood in the veins back to the hearT?
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Postby cheaky monkey on November 23rd, 2005, 1:45 am 

I am not quiet sure, but it could have something to do with the walls of arteries. They are elastic and thus expand when blood is pushed through. The elastic walls of arteries helps reduce the pressure of the blood from the heart.

Blood is pushed back into the heart through the veins via one way valves and pressure from the capillaries.

I hope this helped
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Postby mabus on November 23rd, 2005, 9:24 am 

Actually, you CAN feel your pulse through your veins. Most arteries in your body are fairly deep down inside and when you feel your pulse, with the exception of your neck you are feeling the pulse through veins. Your wrist is a perfect example of veins through which you can easily take your pulse. You are correct though in thinking that the pulse is indeed weaker in veins than it is in arteries, and the reason is distance. The arteries come straight from the heart where it pumps out the blood at maximum force trying to give the blood flow enough force to go around the entire body and back to the heart again. By the time the blood flow enters the veins it has expended a lot of it's force and the pulse is much weaker. That is indeed why arteries are stronger, more elastic and able to sustain more pressure as cheaky suggested. You can test this yourself by testing your pulse on your neck arteries and seeing how strong they are. You will feel a steady THUMP THUMP THUMP. While on the wrist, the veins will give you a fainter thump thump thump.
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Postby trudi on November 25th, 2005, 9:45 pm 

we often see people trying to locate their pulse on the inside of their wrist. If you look there you can see veins but you cannot see the radial artery. When you press on this area, you might locate your pulse because you are pressing the radial artery against the wristbones. Blood in ateries is under higher pressure than it is in vein. The walls of arteries are elastic to withstand the pressure of the blood in them. By comparison the pressure of blood in veins is lower. Veins have valves to ensure that the blood in them flows in one direction, ie. towards the heart.
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Postby Tranquil on January 2nd, 2007, 2:28 pm 

mabus wrote:Actually, you CAN feel your pulse through your veins. Most arteries in your body are fairly deep down inside and when you feel your pulse, with the exception of your neck you are feeling the pulse through veins. Your wrist is a perfect example of veins through which you can easily take your pulse. You are correct though in thinking that the pulse is indeed weaker in veins than it is in arteries, and the reason is distance. The arteries come straight from the heart where it pumps out the blood at maximum force trying to give the blood flow enough force to go around the entire body and back to the heart again. By the time the blood flow enters the veins it has expended a lot of it's force and the pulse is much weaker. That is indeed why arteries are stronger, more elastic and able to sustain more pressure as cheaky suggested. You can test this yourself by testing your pulse on your neck arteries and seeing how strong they are. You will feel a steady THUMP THUMP THUMP. While on the wrist, the veins will give you a fainter thump thump thump.


I disagree with Marbus´s explanation. You dont feel your venous pulse, because of the facts:
1.) veins have greater lumen (diameter) then arteries, thus lower blood pressure
2.) there is more then 5 times greater capacity in veins (80%) that than of arteries (about 20%)
3.) veins have just a small number of smooth mucle cells in their media then arteries thus a little "pressure" serving for contraction
4.) there also a smaller number of sypathetic nerve fibers then in arterial wall
5.) and, finally, when deoxygenated blood comes from arterial end, its pressure is about 15-25 mmHg (correct me If I´m wrong). And when blood is returned in such a low pressure, the large venous system compensates is, so blood flow is continual

So there, are always another factors contributing to blood return: muscle work, gravity, pulsation of arteries etc . . . So I think, that veins does not make "fait thump thump thump" :D


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Postby Macrophage on January 4th, 2007, 5:20 pm 

mabus wrote:While on the wrist, the veins will give you a fainter thump thump thump.


On the wrist, you feel the pulse of the radial artery, not a vein.

Like Tranquil explained, the walls of a vein are different from that of arteries. They both have an inner endothelial layer and an outer connetive tissue layer, but arteries have an intermediate muscular layer. What helps return venous blood to the heart against gravity is muscle contraction (what is called a musculovenous pump) and the fact that usually artery/vein/nerve are in the same neurovascular bundle (enclosed in a common sheath) so the pulse in the arteries also contributes to venous return.

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