Blood is a tissues, or grouping of cells, that move throughout the body of most multicellular organisms. Blood is circulated in order to bring nutrients and assist other parts of the body in normal function. Blood is extremely hard to clean up when it has left the body. Luckily there are many modern products on the market for removing blood stains that would be otherwise impossible to clean up. Many of these products can be found cheaply and easily online.
Blood stains can easily become permanent. An excellent example of this are some of the South American ruins where human sacrificed were performed. Many of these sites are disgustingly plastered with the blood of the victims. Even after hundreds of years of wind, water, and erosion these blood stains are still there. Therefor you definitely want to take special measures to clean blood off of your carpet.
Almost everyone in my family have sinus problems that can be severe. In certain parts of the year, and on some extremely dry years, we can have a bloody nose daily. I have had 3 nose bleeds in one day before. This is can be even worse in dry areas with exceptionally low humidity. I have had to clean both large and small blotches of blood off of my carpet many times.
Blood is extremely hard to remove for a number of reasons. The main reason is because of its dark rich that is so prevalent in the liquid. This color comes from a substance known as hemoglobin. The levels of hemoglobin can change the color of the blood and have a great effect on how hard it is to remove blood stains. Hemoglobin can be effected by diseases such as carbon monoxide poisoning, and also by oxygen levels in the blood. Cyanosis can even make blood take on a blueish tint, while an excess of plasma can make blood carry a more yellow color.
There are two methods I often use to clean up the stains off of the carpet if a few astray drops fall whilst I have a bloody nose. The first method and probably the easiest is to catch it before the blood dries. Simply spray a household cleaner on it, I assume a little dish soap and water might even work, and rub it out with a dishrag. This can take a lot of scrubbing, but it definitely gets the job done. If the blood is dried a little bit then you could try and use hydrogen peroxide, which is usually used to clean the bacteria from cuts and wounds. Just poor a little on the offending spot and let it bubble for a little. Once it stops bubbling then get a rag and scrub the spot out. If the spot has dried you may need a special product to remove it.