Answered By: Addiction Specialist

Answer: To answer this question it is important to first explain the concept of a synapse. A synapse is very small space in between two nerve cells that signals must cross in order to be communicated from one nerve cell to the next. The way a signal is transmitted across a synapse is through the release of chemicals called neurotransmitters. When a signal traveling down one nerve cell reaches the junction with the next cell, it causes the release neurotransmitters into the synapse and these bind to receptors on the receiving nerve cell. Once enough receptors have been bound, the receiving nerve cell fires and the signal continues. After the signal has been communicated, the neurotransmitters return into the first nerve cell so that the second nerve cell knows that the signal is over. Dopamine is one type of neurotransmitter. When cocaine enters the brain it blocks the channels that dopamine uses to get back into the cell that released it. This results in dopamine accumulating in the synapse. This causes the receiving nerve cell to think that the first nerve cell is sending more signals that it really is. The nerve cells that use dopamine are involved in the brain's reward system, so the increased firing caused by cocaine causes the user to experience the same types of good feelings the brain usually only produces when it wants to reinforce a behavior like eating good food, having sex, being praised, or accomplishing something important. Unfortunately, once the brain gets used to cocaine, it becomes difficult or impossible to feel these good feelings without it. Cocaine also increases the firing of nerve cells in the brain's "fight or flight" systems. These are the parts of the brain that are involved in the processing of danger. That is why cocaine also causes a dramatic rise is heart rate, blood pressure, and muscle tension and can lead to heart attacks and strokes.

Answered on: October 13, 2008