Introduction to Psychobiology Part 4 (Psychopharmacoloy/Drugs)


For more information about biopsychology, please check out "Physiology of Behavior" by Neil Carson.

Drugs. Today we are going to talk about drugs. Psychopharmacology is the study of drugs (now it sounds redundant). We are going to explore how they affect mental processes and behavior.

Let's start with the basics: what is a drug? Neil Carson, the author of "Physiology of Behavior" defines a drug as "an exogenous chemical not necessary on normal cellular functioning that significantly alter the functions of certain cells of the body when taken in relatively low doses (1)." Or in simpler terms a chemical that changes the normal functions of the body. We'll tackle this definition one step at a time. Exogenous means outside an organism (2). This makes a reference that there are chemicals inside the body that alters normal somatic functions, but the definition of drugs only focuses on the external ones. We use the term drug effects when referring to these changes caused by drugs. The places where the chemicals attach in order for these changes to occur are called sites of action. The phrase "functions of certain cells of the body" is stated to explain that the focus is, obviously, biological in nature. Finally, the last part, the one about low doses, makes a reference of how almost any substance that is taken in large doses affects the normal cellular process.

By using this definition we can state that coffee is a drug because it has caffeine, which is an exogenous (remember that this means that it comes from the outside of our body) chemical, and when taken in small doses it changes the normal functions of our body by giving us energy and other things. People usually have the idea that drugs are illegal and negative things that only criminals do. Do you remember the phrase "Say no to drugs?" Well, drug effects are also used to help people in the form of medicine. Remember that the stores that sell medication are called drug stores. So, our focus will not deal with the morality of using drugs, but rather with descriptive, non-normative details that surround them.

Where can drugs be administered?

We'll cover five types of ways drugs can be administered. The first one is by means of injection. Moreover, there are several types of injections, one of them is intravenous (IV) injection. This one goes right in to the bloodstream so the drug effects are instantaneous (3). The peritoneal injection, which is administered in the peritoneal cavity (duh!). This is a semipermeable wall in the abdomen (4). The next injection is intramuscular, which is delivered into the muscles and the last one is the subcutaneous injection, which is delivered under the skin (5). The cartoon to the right depicts a peritoneal injection.

The second route to administer a drug is by oral administration. Researchers don't usually use this method for two reasons. The first one is that if the experimenter is dealing with animals, they (the animals, not the researchers) might not want to consume the drug because of its flavor. The other reason is that the chemical can be destroyed by a stomach acid (1). Nevertheless, this method can be used with humans if it is administered with a sublingual method (This means placed under the tongue). In this way, the drug enters the bloodstream, thus, not being affected by the stomach acid.

The third method is called intrarectal and it is administered through the anus (6). I hope you can understand why I didn't put a real photo here. It is important to note that because of they way it is introduced into the body, many researchers opt out of his method. Nevertheless, it is commonly used with humans.

Inhalation is the fourth method. Drugs like marijuana and nicotine are usually smoked (1). This method is efficient in the sense that a lesser dose is needed for the same effect when compared to the other methods such as oral administration (7). The last method is called topical. This is applied to surfaces of the body such as the skin (8). Maybe you have seen this in the form of nicotine patches.

Finally I want to leave you a link of an artist who drew 30 portraits of himself after consuming thirty types of drugs:

Feel free to leave comments, questions, concerns, or suggestions. Thanks for reading!

1. "Physiology of Behavior" by Neil Carson