What Are The Similarities Between Arteries, Veins And Capillaries?

Hey I found the answer with a lot of research so I decided to answer it to help you guys
1) both are blood vessels
2)they can contact or expand soft and fast
3)they do not fatigue in a way muscles do
4)both have three layers
  I.outer tissue
  ii.muscular middle layer
  iii.inner epithilial cells
5)both are formed of smooth muscles
6)both are linked to the heart

Hi I am doing the same project! :D and I could find the answers anywhere, so I thought I should share the answers when I found them out!!
This is probably a bit late but here you go! :

1: They are both blood vessels
2. They are both components of our circulatory system which carry blood around our body
3. They are both formed of smooth muscles
4. They can both contract or expand hard and slow and they can expand or contract fast and
soft
5. They both have 3 layers: An outer tissue, a muscle middle layer and inner epithelial cells!
I hope that helps! Sorry if its too late!

I'm doing the same homework! And... They both have 3 layers, an outer tissue, a muscle middle layer, and inner epithelial cells. (:

The similarities?  Both carry blood.  but if this is for a project, you should research it for yourself.  You can google for information on the circulatory system, or go to many fine medical websites from many clinics around the world.  I'm partial to mayoclinic.com myself, but there are many other excellent sources out there. 

The similarities between arteries, veins and capillaries are that they are each blood vessels which function in blood circulation.

Thanks.....I was also looking for this as it was my homework...