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When blood is deoxygenated and flowing back to the heart through the veins, it is dark reddish-blue in color. Blood in the arteries that is oxygenated and flowing out to the body is bright red. Whereas arterial blood comes out in spurts, venous blood flows.
Egg cells are about the size of a grain of sand. They are formed inside of a female's ovaries before she is even born.
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
Serum cholesterol testing in adults is recommended every 1 to 5 years. People with diabetes and a family history of high cholesterol should be tested even more frequently.
After a vasectomy, it takes about 12 ejaculations to clear out sperm that were already beyond the blocked area.