Previously on Nerd School: The Walking Dead- Off With Their Heads- Katanas in a Post-Walker World, If I Only Had a Brain- Biology and Headshots
This article deals specifically with the TV Show up to Season 3 Episode 2. The article may contains spoilers for anyone not caught up.
What makes the zombie phenomena so grotesque is the method by which the zombie’s body continues to function “after death”. Dead material is supposed to rot, and for it to keep moving defies natural law. However, we know in the universe of The Walking Dead, that the walkers aren’t reanimated by supernatural means. That means that the reanimation and motor processes of the walkers are rooted in the very real world of biology. So, how do these walkers literally keep it together enough to move?
Movement is a fairly simplistic body function to explain. Essentially, our muscles are grouped to effect a part of the body when they expand or contract. There will almost always be a second set of muscles that will expand or contract opposite of the first set. The interaction of the muscles cause “movement”. This is a very specific type of muscle tissue. In our body we actually have three types of muscle tissue, but because the walkers don’t pump blood, we will only focus on skeletal muscles, or those used for movement.
Last week we talked about how the brainstem reanimates the other parts of the brain in order to literally “get things moving.” Aside from brain functioning , the only bodily function that still needs to work in this scenario is movement. Face it, walkers need to walk!
Shortly after death, muscles become flaccid, although they may respond to stimulation for a short time after death. So we have to assume that when the brainstem reanimates the brain, it either restarts muscle movement, or the reflex action.
Reflex is a very simple involuntary and nearly instantaneous movement in response to a stimulus. In that case, we see movement being regulated by the less complex part of the nervous system. That means all movement is only effected by outside stimulus. However, if movement is more complex, that means the walker (or virus acting inside the walker) is making decisions on where and how to move. Both ideas represent a whole host of consequences.
However, it still doesn’t answer how the walker’s muscles continue to function during decomposition. We have to assume that when the muscles are reactivated, either the processes associated with muscle movement are reactivated, or the virus acts in much the same way. So when the brain tells a muscle to contract, the muscle opens its cell membrane to allow in calcium. The calcium sticks to the actin and myosin. This along with ATP makes the muscles contract. ATP is the energy that your cells use made from those same cells using glucose. (This is the simplest explanation of the process so those with medical backgrounds don’t freak out.) So in order for those walkers to keep walking this still needs to happen.
The more interesting and complex issue exists over muscle damage. Even in basic usage, we damage our muscles on a regular basis. When talking about the brain, we saw that the hypothalamus is stimulated showing that it must repress the feelings of fatigue while simultaneously driving hunger. Since, on the show, walkers are still active after at least 10 months, there must be a form of muscle repair.
The walker must have a rudimentary form of circulation which helps fix the tissue. This is probably connected to the hunger function where the “food” helps bring n the necessary requirements to fix the muscle, namely protein. Without a food source the walker would probably “cannibalize” their own bodies. They would metabolize their fat storage, which probably explains the emaciated looks of the walkers. Not to mention the oxygen aspect necessary as well, meaning that there may be a form of respiration occurring as well. Granted this is not consistently or even indefinitely continuing. The fact that the muscles are continually being used without proper time to relax would lead to complete breakdown. The muscles that weren’t being used would eventually atrophy.
Think about this then, if the walkers have rudimentary brain power, circulation, and respiration, are they truly “the walking dead”? They seem pretty alive in analysis of the situation. In fact most of the processes we associate with life seem to be functioning (reproduction is unknown thankfully).
This is even more terrifying, as our heroes are no longer killing monsters, they really are killing living (somewhat) humans.
Read Joe’s other articles:
Game of Thrones: Casting Roundup 1 and 2, Game of Thrones Primer II, Game of Thrones Primer I, Inn at the Crossroads Interview, Season 1 recap, The Greyjoy Rebellion, Robert’s Rebellion Pt.1, Robert’s Rebellion Pt.2, Robert’s Rebellion Pt. 3, The Religions of Westeros, The Races of Westeros