Scitech | Top five things in your body that should kill you (but don’t)

Jenna Blumenthal investigates how destructive parts of your body can be, and how adept your body is at exploiting these functions for the better.

Gut flora (microorganisms taking refuge on your insides)

Why it should kill you:

Your intestines are crawling with trillions of bacteria and other microbes, many of which are indistinguishable from those that make you ill. An entire ecosystem of organisms lines the inside of your gut, uniquely adapted to surviving the harsh conditions of the human intestine. Not only are these microbes loitering inside you, they are clever enough to obtain necessary resources directly from your body. If the integrity of the intestinal wall is breached, these bacteria can invade the host (you) and become a threat.

What it does instead:

The constant interaction with these unique organisms serves several valuable functions. They ferment non-digestible materials (such as unabsorbed alcohol and gum) and are key players in normal immune resistance. When the body interacts with these microorganisms, it learns about the external environment and cultivates specialized responses to antigens, essential for the development of a capable immune system. The organisms themselves barricade invading pathogens by competing for space and nutrition, and release antimicrobial substances to limit the proliferation of harmful bacteria.

 

Apoptosis (programmed cellular suicide)

Why it should kill you:

Believe it or not, your cells are programmed to die. Upon receiving appropriate signals, the cell can activate a class of internal proteins that wreak havoc on organelles. Other activated proteins attack the cell’s DNA, destroying any possibility of normal cell function. Apoptosis can be triggered by molecular binding of the cell’s “death receptors” – unprotected surface proteins that, when stimulated, initiate a series of reactions that lead to breakdown of the cellular membrane, cell shrinkage, and DNA fragmentation.

What it does instead:

Apoptosis is a tightly regulated process, and ridding the system of unneeded cells is important in maintaining healthy body function. In some cases, excess cells are produced and only those that properly mature survive. Programmed cell death serves as a practical self-editing mechanism, enabling the body to keep only the beneficial cells around. Surrounding cells keep a close check on this degradation, engulfing the leftover fragments before any damage to the body can occur.

 

Activation-Induced Deaminase (AID)

Why it should kill you:

AID is a simple protein that distorts normal patterns of DNA by deliberately introducing mutations. By rearranging the chemical composition of DNA molecules, this process will transform the proteins that will then be produced by the cell. Manipulating genomic material can have detrimental effects, including disrupting the cell’s usual activity and encouraging the growth of malignancies.

What it does instead:

At any given moment, an overwhelmingly large population of pathogens can enter your body, which your immune system must battle. AID’s unique abilities to induce random genetic mutations in certain immune cells is harnessed; accelerating the evolutionary process and generating a wide range of highly differentiated cells enabling individualized response to specific antigenic substances. Thankfully, precise regulators that restrict AID’s potentially damaging activity to particular cells of the immune system silence unwelcomed mutagenesis in the rest of your body.

 

Neural adaptation

Why it should kill you:

Neurons are lazy. In a complete affront to all logical thought, many sensory neurons become less responsive when confronted with continuous stimulus. They’ll respond to the onset of stimuli, but do not continue to convey this information if the stimulus persists. Your neurons tire of sending the same sensory information to your brain, and, if you think about it, this should have some pretty heinous effects on all neurological functions. If your brain doesn’t get updated, how can proper control persist?

What it does instead:

The body is magnificent. Not only can it decide which sensory information is important, it actually assigns individual properties to different neurons depending on their role. For something like pain receptors, neurons do not exhibit this lethargy; you continue to acknowledge pain even if it is unaltered. However, right now you probably aren’t thinking about the fact that your foot is still touching the floor, and perhaps that nasty locker room odour has become tolerable. This is a direct result of your neural system’s ability to adaptively silence redundant sensory information.

 

Killer T Cells

Why it should kill you:

Killer T Cells are important to the immune response. But instead of reacting to invading bacteria or viruses, Killer Ts attack your own cells. Unlike other immune cells, Killer Ts can’t even recognize these pathogens; their activity is limited exclusively to attacking the organism’s own cells. When active, Killer Ts release “cytotoxic granules” that can bind to the target cell’s membrane and induce apoptosis.

What it does instead:

The regulation of our own cells is our main defence against viruses and cancers. Other cells in the immune system often miss viral infections because viruses don’t float around the space between cells, like bacteria – they hide inside human cells. Killer Ts become activated when they bind to cells that are infected with a virus or have genetic alterations associated with cancers. When a cell becomes damaged, it presents a specific receptor on its surface that stimulates the Killer Ts, confining their prolific killing abilities to only those cells that may harm the body.


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