Working organs.
Turns out that many of the organs in a vampire will still work the same way they work in a human. This is because these vampires were once humans and as such have human parts.
Brain.
Vampires still have brain waves in their functional brains. The brains are not slow, are some are even faster than human brains. One difference with brains is that there is no agreed death, like blunt force to the brain (e.g. lead bullet) will not stop the brain from working (death). To completely stop the brain from working, it needs to be deprived of nutrients completely, such as by squashing of cutting off and leaving the head alone to be malnourished.
Circulatory system.
The circulatory of vampires are also functional. This is because they need blood to carry nutrients to parts of the body where they are needed, and also need blood to carry wastes out of the body. One thing with circulatory system is that, it does not produce its own blood.
Musculoskeletal system
Research has shown that this is a result of defective bone marrow. 25
Evolution of the vampires system has made vampires hungry for human blood, as getting external blood supply via per oral, frequently non consensual transfusion (sucking victims), is the standard way to survive their defective bone marrow. They could also consume animal blood, usually bovine blood, but they will just get hungry quick again, because their immune system recognized bovine blood as a foreign body and secrets antibodies to destroy them.
They also cannot synthesize much vitamin D. This is because they do not get enough sunlight due to the hypersensitivity of their skin to ultra violet spectrum of rays from the sun.
The vampire musculoskeletal system is highly regenerative. Broken bones and dislocated joints gets fixed in minutes and can get completely back to normal in less than an hour. This regenerating process is inhibited by silver metal, which also poisons the vampire body. Another fascinating part of their skeletal system is the ability grow longer canine teeth which looks like fangs, and longer nails, like human claws.
Cellular functions
Adult vampires experiences a very slow cellular duplication and apoptosis. This is because the slow replication contributes to very slow aging and telomeres lasting longer, this is unlike cancerous and tumor cells which grows out of proportion. This contributes to vampires having very long lives. 25