Melissa Osman
Elasticity of blood vessels
Introduction
There are many blood vessels in the body. There are two main ones, arteries and veins. These blood vessels are able to expand in order to let more blood flow through them. They also contract to help control the flow of blood.
Blood is pumped out of the heart to the body via the arteries and the veins carry the blood back to the heart. When the blood is in the blood vessels, pressure is present. In the arteries the blood is at higher pressure than it is when in the veins, arteries also have thicker walls (due to the high pressure) than the walls of the veins.
The elasticity of arteries is what sustains the pressure on the blood when the heart relaxes and keeps the blood flowing in a forward direction.
In the following experiment, we observed the elasticity of veins and arteries so that we could determine the differences in elasticity and if this affects the pressure within the vessels.
Hypothesis: Due to the scientific background about veins and arteries, it would be expected that the elasticity of the arteries is higher than the elasticity of veins. It is expected that the length of the arteries and veins will increase as the weights are added. The arteries have a larger lumen, with more muscle, therefore leading us to predict that the length of the artery will return to the ‘same’ (nearly the same) length once the weights are removed. Due to the structure of the veins, the length may not return to the original length as much as the artery.
Materials and methods
To carry out this experiment, weights of 10g each were used. A paper clip was used to hook the piece of artery and vein; a retort stand was also used to place the paper clip on and in order to hold the ruler in place. The ruler was used to measure the distance travelled according with the applied force. In order to place the weights on the artery a weight holder was used and this was placed on the piece of artery/vein. Three pieces of artery and vein were cut to around 2-3mm thick. The first thing to do was to test the elasticity of the artery. The apparatus was set up accordingly and the piece of artery was placed onto the paper clip. The length of the artery was then measured whilst it had no extra weight added to it. After this, a 10g weight was placed onto the weight holder, which was attached to the artery. The length was then measured and recorded. Another weight was then added on top of the previous weight, making the weight equal to 20g. The length of the artery was then recorded. Thereafter the addition of weights continued until it reached 100g, at each time adding 10g, whilst recording the length at each new weight.
