Quote:
Originally Posted by Glasgowgirl
Usually the darker the blood the more oxygen it has in it thats why blood flow close to arteries is much darker..
I don't believe that's true for blood in your circulatory system; oxygen depleted blood is DARKER, blood containing oxygen is brighter. When you have a cut, notice the blood comes out bright red. HOwever, dab it on a tissue and wait few minutes, it will brown- this is because the blood is dried and not recycled in the system. Hemoglobin, the porphyrin in the erythrocyte (red blood cell) is gives a naturally red pigment, and becomes brighter as it binds to oxygen it in the lungs.
HOwever, I can't promise anything about the female menstrual cycle- That blood on the uterine wall doesn't function like the blood in the circulatory system.