The
cellular communication language
You are standing in the kitchen,
cooking a delicious Thai curry for dinner. While reaching behind the pan for
the onions and chili peppers you accidently touch the edge of the boiling hot
pan! Before actually consciously realizing it your hand automatically shoots
away from the object that hurt your hand so much. When you finally get what
happened you put your hand under cold water. But how is it possible for your
body to react so fast and how does the information that you touched a boiling
hot pan sent from the sensory cells in your fingers to your brain cells and
back to muscle cells in your hand to tell to retract your hand?
First of all, there are different
manners of communication between cells in your body. Some cells are neighbors
while others are so far away it is like they live at the other side of the country,
however even these signals that have to travel large distances through the body
reach their final destination. Signaling to cells that are neighbors or live in
the same neighborhood is called paracrine signaling (figure 1) and signaling to
cells far away from each other is called endocrine. A cell can also sent
information to itself, this is autocrine signaling. In the communication
between cells, there are a couple of different stages. Taking the example of
burning yourself, the first thing that happens is the stage called reception. A
sensory cell is triggered to send a signal to your brain because it receives a
pain signal. This signal is sent, because transduction has taken place, this
means that different proteins in the cell have activated each other and made
the cell send a signal directly to the nervous system or first other cells,
however eventually the signal is sent through the nervous system to the brain.
In the brain this signal of pain is processed, and you feel the pain when this
signal has reached the brain, not before that moment. But all these signals
your body is constantly receiving and sending that you don’t notice the minute
delay. In your brain a signal is sent from the signal receiving area to the
part of the brain which takes care of muscle reflexes when you experience
extreme pain suddenly. From here a signal is sent via the nervous system to the
muscle cells in your arm, this makes your body retract your hand from the
painful and, in this case also, hot object.
Figure 1: Autocrine, paracrine and endocrine signaling. |
Now it is more clear how signals are sent within the body, but what are
these signals exactly? There are different types of molecules which are sent by
cells to be received by other cells within your body. One type of very
well-known signal molecules are hormones, examples of these can be the sex
hormones, testosterone and estrogen. The actual structure of these hormones is
not very different, but different enough for the human body to be able to read
the difference. When you go into puberty hormones are sent all over your body
to influence different processes, hormones are able to travel large distances
in the body. Not all cells however are sensitive or influenced by a specific
hormone, estrogen will not be recognized by a cell in the tissue of your toe, but
breast cells have estrogen receptors to which estrogen can bind and change the
cells behavior. Another example of a signaling molecule is a neurotransmitter,
these are the signaling molecules of the nervous system and travel through the
nerves in your body to pass on signals from one part of the body to the other.
Dopamine is a neurotransmitter which makes you feel
good, there are different
drug which have the same kind of structure as dopamine and can bind to the same
receptor to create the same response of feeling really good, making these kind
of drugs very addictive.
Just try to imagine the amount of
information sent through your body by communicating cells, the amount you are
imagining probably doesn’t come close to the actual amount. Also how fast all
these processes go is incredible and extra reason to be happy with your fast
responding body the next time you accidently touch a boiling hot pan while
cooking.
By Laurine van Gijn, 8/10/2015
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