Natural Pathways in the Brain
In the brain, networks of neurons form, each with an axon, dendrites, soma, myelin sheath, nodes of ranvier, synaptic cleft, and an axon hillock. They send chemical and electrical signals to control sensory feelings and motor functions. For example, the reward pathway uses signals from sensory neurons so you are rewarded for advantageous behavior like eating, drinking, and reproduction. It creates this feeling so you are more likely to complete this action again.
These neurons communicate through the synapse. The small area between the sending neuron and the receiving neuron is known as the synaptic cleft. At the end of the sending neuron are vesicles, small packets that hold together neurotransmitters. In the reward pathway, the neurotransmitter of choice is dopamine. Once an axon reaches its action potential, it lets in Ca++ ions, which triggers the vesicles to release. They spill into the synaptic gap, and make their way into the dopamine receptors at the end of the receiving neuron. The dopamine receptors trigger a second messenger to be created, which then triggers a nerve impulse that releases any neurotransmitter of the axon of the receiving cell. The receiving cell then becomes the sending cell and the process repeats.
However, glial cells also function to assist the neurons. There are three main types of glial cells: oligodendrocytes, microglia, and astrocytes. Oligodendrocytes form the myelin sheath, speeding up chemical impulses during action potential while protecting the axon, too. They are made of lipids, or fats. Microglia defend the neurons, chomping up any invading bacteria. Astrocytes are the arguably the most important and mysterious of all glia, that keep the structural integrity of the neuron, while feeding it nutrients and eating any unneeded neurons. Also, they regulate blood flow with "end feet" on blood vessels. But above all, they can create and modify transmission. These are known as "gliotransmitters". Scientists are confused on the process, but the astrocytes are extremely involved with Alzheimer's, ALS, and AIDS.
Drugs Alter the Brain's Reward Pathway
How drugs work
All drugs either inhibit or excite the release of neurotransmitters and their associated processes. These include alcohol, anabolic steroids, cocaine, dissociative drugs, GHB, Rohypnol, hallucinogens, heroin, inhalants, marijuana, MDMA, methamphetamine, and nicotine. Drugs emphatically change the way the brain works quickly. For example, methamphetamine triggers the quick release of dopamine into the synapse throughout the reward system, causing addiction due to the reward of having something that chemically makes you happy. Also, the quicker the drug causes a high, the more addictive it is.
What drugs do to you
Drugs truly rewire the brain. Even a one-time abuser will have decreased brain activity due to the extreme releases of dopamine. Because of this, the brain tries to compensate for large release, so the brain needs even more the next time to get high. All of the brain is affected by drugs, even the decision making, judgement, memory and movement parts. Another consequence of this rewiring is the subconscious seeking for drugs.
Also, immense health effects are incurred. Heroin and alcohol both cause constriction of the airways, which can easily lead to death, especially when combined. Heroin constricts the airways by increasing levels of the inhibitory GABA, while alcohol decreases the excitatory glutamate to constrict the airways. Alcohol can also cause unconsciousness and vomiting. All stimulants can cause heart attacks, overheating, and brain damage due to popped blood vessels. All smoking can cause lung cancer, throat cancer, esophageal cancer, and strokes.
Reward Pathway: Your information was very thorough. It seemed to me that you didn't really need the information about the parts of a neuron, and it was just white noise. You also could have touched more on the process of the reward pathway and how it works. There was an animation with a woman that had an abnormally large mouth that could have given you tons of info. The writing seemed more about neurons and action potential then the reward pathway itself. Terminology use was great.
ReplyDeleteDrugs: The information was very concise and I liked that. It was nice that you listed all of the drugs that do cause dopamine to be released. It was good that you included a "How Drugs Work" section, as this background information was vital to the understanding of the rest of the information. Good job!
You did a great job on this luke. I could tell that you spent a good amount of time reading through the whole website. Your information was understandable and very detailed it provided a wonderful overview of the topic. I also liked the way you organized it, that was clever.
ReplyDeleteUmm, did we look at the same site? ;) Jk. But seriously, you have a ton of facts for the Pathway, so nice job! :D You did really good by summarizing the important facts and making it clear and understandable. You were fairly even with both the Reward Pathway and the Drug section, but maybe this is just a personal preference, but I think you could have covered more on the Drug part. Or maybe that's just me 'cause I was really interested in that subject. ^_^" Great job though! :)
ReplyDeleteNatural Pathways in the Brain: I liked how you started out with the basics. How you explained a neuron and how it worked. This will help out to people who haven't even learned about the affects of drugs before. I don't know if it was needed though.
ReplyDeleteDrugs Alter the Brain's Reward Pathway: This was good because the information was to the point and full of facts and info. When you started the "what drugs do to you" paragraph i liked how you started it out with a sort of shocking first sentence. Keep it up!