Note: this was originally posted on my blog on tumblr.com. I have tried to convert some of the formatting over, however there may be some inconsistencies. Also this particular entry was written before I knew how to cite scientific sources, so sources will either be nonexistent or incorrectly cited.
Initially the powers seen by the characters in Heroes were explained by purely genetic means, a character has a mutation that means that they have an ability. However later in the show it was revealed that adrenaline (also called epinephrine) played a major role in the function of their powers. So how does the genetics of the abilities in Heroes play into the actual function of epinephrine? How can a hormone be interconnected with genetics?
Let’s start by looking at how hormones work. Hormones are produced by the endocrine system, which is one of the two ways that your brain tells your body what to do. The other is the nervous system. The nervous system deals in nerves and fast responses, like slapping someone in the face. The endocrine system deals with slow change, like puberty. The effects of a hormone from the endocrine system can last days or hours while a signal from a neuron doesn’t even last a second.
The endocrine system functions on a series of glands. The main gland is the pituitary gland, which tells all the other glands in the body what to do. The pituitary gland talks to the hypothalamus, a region of the brain which functions as a liaison between the nervous system and the endocrine system. So let’s say that all of a sudden you are punched in the face. Thankfully this doesn’t happen to you often so it comes as shock. Your nerves tell your brain that you are in pain and that someone just punched you in the face. Your brain tells you hypothalamus which then tells your pituitary what went down. Your pituitary then signals your adrenal glands to secrete adrenaline so that you can get away. Or I guess you could punch them back, if that’s really your style.
So what is this magical adrenaline that you hear so much about? Adrenaline (which is going to be called epinephrine for the rest of this because that’s its technical name) is a hormone secreted by the adrenal glands. Adrenal glands usually regulate the amount of salt in your kidneys, but they also produce epinephrine that allows your body to react to a stressful response. Epinephrine is a water soluble peptide hormone, which means that unlike other types of hormones it cannot directly enter into the fatty cell walls of human cells. Fat and water don’t really mix. Instead it has to use a receptor to enter. It is also a neurotransmitter, so it also functions in the nervous system so you have both a slow response (hormonal) and a fast response (nervous).
The epinephrine is released from the adrenal gland into the bloodstream where it travels around the body. The hormone bounces around the bloodstream until it finds a cell with the right kind of receptor (which is like a little flag that tells the hormone that it can bind this this type of cell, epinephrine likes G receptors in particular). When it finds a receptor it binds to it. This binding causes the receptor to change it shape, causing a series of things to happen within the cell, the end product being an increase enzyme expression within the cell. Enzymes work to speed up reactions. This then changes gene expression.
This causes a normal person have a heightened sense to smell, for the muscles and blood vessels to contract, the pupil dilate, and there is increased blood flow to the heart and lungs paired with decreased blood flow to the stomach. These changes last a few minutes to a few hours and then the cells return back to their normal pre epinephrine functioning.
Let’s say, hypothetically, a person with abilities gets hit with a truck driven by the mob. Their body would release epinephrine in response. Gene expression would change throughout their body so that they had all the responses as a normal person. However the epinephrine would also “turn on” the genes that regulate their ability. The proteins needed for that ability would then be manufactured and they would, hypothetically, be able to fly away to get away from the danger of the mafia.
In some specials it appears that this change works much like normal epinephrine responses in cells. The person is able to use their ability to escape the stress and then once the stress stimulus has disappeared the gene expression returns to normal and they no longer are expressing the ability. This is why you don’t see Nathan flying all the time. He can walk perfectly normally because the genes are turned “off”.
There are other specials, like the Haitian, who always have the genes that express their ability “on”. The Haitian always is able to repress abilities, he doesn’t need a stressor or certain conditions. A special in this situation has had their gene expression permanently changed, which can rarely happen with epinephrine. Initially when their ability was manifested there was a stressor, one that was probably extremely large or lasted an very long period of time that caused the hormone to stay in the person’s system for so long that they simply never reverted back to normal genetic expression once the stress has passed.
This could actually be extremely dangerous. If the sympathetic nervous system (the part of the nervous system involving epinephrine) is activated for too long it causes anxiety. Anxiety for an extended period of time can lead to diabetes, heart disease, high blood pressure, and infertility. Over even longer periods of time it can also cause the ends of your DNA to unravel or for your cells to become oxidized. Your cells literally rust. If a person were to receive a large amount of epinephrine in a short amount of time, they could literally die. This what happens when someone is “scared to death”. There are two main ways that this happens, either by heat attack or broken heart syndrome that causes the heart to contract so tightly it cannot pump blood. All of these results from epinephrine have certain genetic groups that are predisposed to experiencing them. So unless specials have a series of mutations that allow them to experience a large amount of epinephrine over a long period of time they would not have a very long life span, or at least not very much to look forward to later in life.
A post I made about turning “on” and “off” genes (x)
Crash Course Biology’s video on the Endocrine system (x)
Molecular Cell Biology, 2000. WH Freemen and Company (excerpt used)