Daily Archives: May 29, 2009

G-Proteins: The Molecular Switch

Imagine you are a soldier on a very dangerous patrol in Afghanistan. While your conscious brain attends to the environment, looking for suspicious activity, the unconscious part of your brain is busy altering your body’s physiology in anticipation of an impending threat. Your heart will start to beat faster and much of your blood that would otherwise be traveling to your kidneys and digestive organs is rerouted to your muscles and nervous system. The liver dumps extra sugar into your blood and the airways in your lungs open wider, allowing them to deliver more oxygen to the blood that pulses more quickly. Your sweat glands are more active and the pupils of your eyes dilate. This is what is called the “fight or flight” response, made possible by the hormone epinephrine, better known as adrenalin. The net result of this response is that your muscles are stronger and faster and your brain is more alert. In other words, your body is optimized to fight the enemy, or if need be, to flee.

To get from the state of fear to a body that is better able to respond to fear, many signal “transitions” are involved. The awareness of a threat is “translated” into an electric current that travels along a distinct network of nerves known as the sympathetic nervous system. The electric current is then “translated” into a release of the hormone epinephrine. This hormone will then bind receptors on heart muscle cells, blood vessels cells, liver cells, etc. Thus cells will then “translate” the message of “epinephrine” into rising levels of cyclic AMP (cAMP) inside the cell. In other words, “fear” becomes high cellular concentrations of cAMP, which in turn activate a circuit of proteins to bring about altered cellular activity, which then results in the effects cited above.

Continue reading