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Hello everyone and welcome back. In this section we begin to discuss aspects related to pharmacology. This section is broken down into several major groups. The first is basically an overview of brain structures and how they work. The second section relates so more specific things related to substance abuse such as how you put drugs into the system, how you get them out, etc. Finally there is a third section that talks about a variety of different drugs found in the major categories.

So, let's talk first of all about an overview of the brain and brain structures and how they work. First of all, you need to remember is that when you talk about the brain all parts are interrelated and you need all parts to function normally. There is a structure in the brain called neurons. Neurons are what we call basically nerve cells. So when we talk about nerve cells that is what we will be describing them as throughout the rest of this section.

Let's talk about the nervous system a little bit on slide three. As you can see here, the nervous system is composed of two parts. The central nervous system which consists of all the brain structures and neurons located in the brain and spinal cord. And, the peripheral nervous system which consists of all neurons that are located outside the brain and spinal cord.

Let's talk about the peripheral nervous system on slide four first. The peripheral nervous system contains of two major divisions; the Somatic system and the autonomic system.

The somatic system as we see on slide five consists of what we call afferent neurons. Afferent neurons are sensory in nature. What they do is receive information from the outside world through sensory receptors and then send that information toward the central nervous system.

Efferent neurons on the other hand are motor in nature. What they basically do is get their information from the central nervous system and sends it to the muscles of the body. The somatic system consists of Afferent and Efferent neurons.

The other major system within the peripheral nervous system is the Autonomic System. The Autonomic system as we see in slide seven consists of neurons that go to and from a variety of different internal organs. Basically this system regulates your heart rate, blood pressure, digestion, etc. It has two major parts, the sympathetic nervous system and the parasympathetic nervous system.

The best way to describe this to you is by what happens when you are being chased by a lion. Let's talk a little bit of that and you follow along on slide eight. Let's say you are out in the wilderness, kind of just hanging out. And over there you see a lion, and the lion also sees you. So, you start to run. What do you need to do to run fast? You need to increase your heart rate, increase your respiration to get more oxygen to the cells and you really do not need your digestive system so that system will be shutting down a little bit. So, you run over and get up into a tree and then way up in the tree you are safe. Now you have a real fast heart rate and real high blood pressure, etc. So, what do you need to do? You need to decrease your heart rate. You need to decrease your respiration. And you need to replenish all the stuff you just used getting away from the lion. So, in essence what your sympathetic system does is increase most structures that are related to flight while your parasympathetic system decreases those structures and is more concerned with helping you to slow down and replenish the energy reserves you had. So that is the peripheral nervous system.

What about the Central Nervous System? As we can see in slide nine, the Central Nervous System consists of two major kinds of structures, the brain and the spinal cord.

Let's talk about the brain first on slide ten. First of all, the brain has approximately one hundred billion nerve cells or what we call neurons. The neurons are the functional unit of the brain. In addition to these hundred billion nerve cells we also have approximately one hundred twenty billion Glial cells. The combination of all those things is that you have lots of different types of cells and lots of cells that you have within your brain.

Let's talk about Glial cells for a second on slide eleven. As you can see here, Glial cells have many, many functions. First of all they act as a glue to hold cells and neurons in place. They also help to provide nutrients to the cell. They help to regulate brain activity; in fact they are one of the most important cells in relation to controlling potassium which is highly involved with epilepsy. They are also there to help eliminate wastes, break down neurotransmitters, and also make a fatty substance that surrounds certain types of nerve cells and structures called axions, and this substance is called myelin.

The best way to conceptualize the brain is the concept of how it goes through evolution.

As we can see on slide thirteen, the first major sets of structures that begin to developed is called the Hind brain or what is also called the Reptilian Brain. The hind brain consists of three major groups of structures; the Medulla, the Pons, and the Cerebellum. So let's talk about each of these for a second.

The Medulla, as we can see on slide fourteen, is one of the most important structures that you have. It's going to control your breathing, your heart rate, your blood pressure, your temperature, and all the other things. Basically it is the structure that keeps you alive. You can damage a lot of other brain structures that you have in your system and still live, but if you damage the Medulla, you usually die.

The Pons on the other hand for this class as we see in slide fifteen, is primarily responsible for wakefulness or the sleep cycle.

The Cerebellum on the other hand as we can see in slide sixteen, is extremely, extremely important. It is above the medulla and the pons. What it basically does is help control body tone and body balance. It also helps to coordinate a lot of your voluntary muscle movement. Basically what it does is it smoothes out the jerks you might have from your muscles. The cerebellum is extremely, extremely, extremely important for controlling rapid movement such as startle responses and for maintaining body balance. It also has a major role in remembering things such as procedural memories. Procedural memories are things such as riding bikes, riding a skateboard, skiing, etc. It is also the first structures influenced by alcohol and other drugs.

The Midbrain on the other hand as we can see on slide seventeen, consists of two major sets of structures for this class.

The superior colliculi as you see in slide eighteen, and superior here does not mean one is better than another. Superior in the anatomical sense is of one being above the other. The Superior Colliculus function is, basically, to receive information from the retina of your eye and then to continue to send it on to your visual cortex. The Superior Colliculus is extremely important for controlling eye movements especially tracking. So if a person who is taking substances is having problems tracking, in all likelihood they have consumed enough substances to influence this structure.

The inferior Colliculus on the other hand, inferior meaning below, receives information from the cochlea of the ear then sends the information to the cortex and like the superior colliculus it has a major role in organizing stimuli that we have coming into our system.

The Reticular Formation as we see in slide twenty is another part of the midbrain. What it does is receive fibers from the lower brain stem structures and extends those fibers all the way up into the Thalamus. Thus the reticular formation has fibers in both the hind brain and the mid brain.

Its function is extremely important in controlling your state of arousal. As we can see in slide twenty-one it also has a major role in sleep and generally it's entire focus and function is to act as a filter. What it does is focus your attention on things that are important rather than on things that are not important. For example, it is important for you to be listening to me and not listening to the buzz of the light that is over there in the corner. The reticular formation is impacted by a lot of different drugs and we will talk about some of these shortly.

There is another major concept that you talk about when you talk about the nervous system and that structure is called the brain stem. The brain stem consists of all the structures in both the hind brain and the mid brain. So, if one damaged other brain structures such as your cortex and you still had hind brain structures and mid brain structures intact, in all likelihood you could be alive. Now, you would be in a vegetative state and there have been several recent court cases relating to that but you would be still alive.

So, we have talked about the hind brain and the mid brain. What about the next major group of structures? That is what we call the forebrain. The forebrain as we see in slide twenty-three consists of several structures located within two major areas. The diencephalon or what we call the inter brain and the telencephalon which we call the end brain.

Let's talk about the diencephalon first. The diencephalon as we see in slide twenty-four consists of a wide variety of different structures. For us there is only two we need to know about, the Thalamus and the other is the Hypothalamus.

The thalamus as we see is slide twenty-five is a relay station. It receives information from the sensory system, sends it to the cortex and it sends information from the cortex to sensory systems. It is basically a major integrating and collecting center for all sorts of information. The classic example is listed a little bit below. For example eighty percent of all fibers from the optic nerve first go to the thalamus before they go to other brain structures, such as the occipital lobe. The thalamus also has a major role in memory formation and is impacted by a wide variety of different drugs.

The hypothalamus on the other hand as we see in slide twenty-six, also has a major role. It is located below the thalamus and in front of it. So the "hypo" is meaning "below."

It is also in charge of several different things. Some of these are shown on slide twenty-seven. For example, it governs eating, drinking, and sexual behavior. It also regulates endocrine activity, that is, hormonal activity. It is involved with emotion and is highly involved, for this class, with pleasure circuits.

The telencehalon on the other hand consist of a series of structures that have increased the most as evolution has progressed. It consists of several major groups.

The first of these as you see in slide twenty-nine is the olfactory system and as you can probably tell the Olfactory system is involved with smell.

The second major group is the limbic system and this is shown in slide thirty. It has a variety of different structures including septal, amygdala, the hippocampus which is part of the diencephelon and the parahippocampus. Let's talk about a few of these here for a second.

The septal area as we see in slide thirty-one is involved with controlling aggression and pleasure.

The amygdala as we can see in slide thirty-two primarily controls rage behavior and aggression. When you go in and destroy this structure the animal will attack anything. For example, you take a rat, put it in a cage with a cat and what does the rat do? The rat runs around and tries to get away from the cat. You take the rat out of the cage, destroy the amygdala, let it heal, put it back in with the cat, and the rat will attack the cat.

The hippocampus and the parahippocampus as we see in slide thirty-three are extremely, extremely important. These structures have major roles in memory formation. When you damage these structures you cannot form any new memories. This structure is also one that shuts down when taking a wide variety of drugs including alcohol, depressants, opiates and others. Its shutdown is the cause of memory loss related to blackouts. It is also the reason you experience memory loss when certain types of drugs are given in surgeries such as Vesvid.

The Limbic system as we see in slide thirty-four basically controls animal instinctive behavior. It is also involved with the pleasure circuits that we saw with the hypothalamus earlier and has a large number of dopamine pathways. This is one of the major structures and groups of structures that are involved with the feeling of the pleasure you get when you take certain types of drugs. What about other systems?

As you can see in slide thirty-five the Basal Ganglia is also a major structure within the telecephalon. It has several structures as well, and these are listed here.

Like the cerebellum as we see in slide thirty-six the Basal Ganglia is involved with movement. While the cerebellum controls rapid movements; the Basal Ganglia is primarily involved with slower movements such as starting and stopping movement. It is also extremely, extremely important in relation to balance.

So in general as we see in slide thirty seven the basal ganglia is going to control the direction and the amplitude of a movement; especially postural movements.

When you damage the structure as we see in slide thirty-eight you get lots of problems with posture, walking, etc. The basic symptom of damage to the basal ganglia is what we call a tremor at rest. This is the classic symptom we see with Parkinson's syndrome. Now, once you start to move the tremor stops until in the later stages of the disease. The reason you get this type of disorder is because the Substantial Nigra degenerates. The Substantial Nigra can be impacted by a wide variety of different types of drugs.

The Neocortex is the next major group of structures we see in the telecephalon. It is also called the Cortex or Pallium.

The Neocortex as we see in slide forty is the most developed in humans. It consists of a wide variety of folds or fissures that we call gyri for the folds and sulci for the fissures. That is, the gyrus is for multiples and sulcus is for the singles. This is what you see when you look at the brain from the outside.

The neocortex as we see in slide forty-one is divided into several sections or what we call lobes. Each lobe is separated and has a different function. The cortex is first separated in half by a fissure called the central fissure and this basically splits the brain into the left and right side which we call the hemispheres.

The hemispheres as we see in slide forty-two have different functions. First of all, in general, the left hemisphere controls the right side of the body and the right hemisphere controls the left side. Each of these hemispheres has four lobes and they are listed here.

Each lobe as we can see in slide forty-three is separated by a fissure. For us there are three important fissures. The central sulcus which separates the frontal and parietal lobe. The lateral sulcus which separates the temporal lobe from the frontal and parietal lobe. And the Parietal Occipital sulcus which separates the Parietal lobe from the occipital lobe.

Let's talk about the lobes of the brain for a minute. As you can see in slide forty-four there are four different groups.

The first of these is located on slide forty-five and is called the frontal lobe. The frontal lobe is also called the Precentral Gyrus or Area four. It is primarily responsible for motor movement. In addition to that we also have two other movements Area six and Area eight. Both of these are responsible for muscle tone and getting muscles ready to fire.

To get muscle movement as we see in slide forty-six, Areas six and eight basically prepare muscles to contract. Then Area four causes the muscle to contract. The Basal Ganglia, Cerebellum, and other structures help to smooth out the movements so it does not appear jerky.

Now one structure located at the bottom areas of four, six, and eight is called Broca's Area. This area is primarily concerned with speech. When this is damaged, the person can understand speech, but they cannot talk very well and this has been diagnosed as Broca's Aphasia.

Now outside of these major structures there are other areas and these areas are called Association Areas. As we see in slide forty-eight these structures are extremely important for thought processing, memory formation, and problem solving. When you damage these areas you often times have lots of problems with memory. This is very important in relation to substance abuse because often times these systems are shut down due to substance abuse over time. Ultimately, these systems can actually die.

The next major set of lobes as we see in slide forty-nine are what we call the parietal lobes. And like the frontal lobes they contain a variety of structures. The first major area is what we call Area three or what is called the Somatosensory area. This structure is primarily concerned with sensory functioning. This is where you feel pain, temperature, etc. In addition to that we also have other areas called Area one and Area two, and also association cortex. These basically interpret what is going on in Area three.

The next major area is called the temporal lobe as we see in slide fifty. It is primarily concerned with speech and hearing and is located below the Lateral Sulcus. One of major structures within the temporal area is Wernicke's Area.

As we can see in slide fifty-one, Wernicke's Area is primarily concerned with the integration and comprehension of speech. It also receives information from a wide variety of other structures such as the occipital lobe. When you damage this structure you can speak fluently but the content is nonsense, and this is called Wernicke's Aphasia. In addition to that, when you damage the structure, it is often hard to comprehend and understand even written stimuli such as reading. This structure is often impacted by substance abuse and causes many, many problems with integration and processing and trying to get information out, say to your counselor or some other person, etc.

Now to assist the information processing there is a structure that connects Wernicke's area and Broca's area and this structure is identified on slide fifty-two and it is called the Arculate Fasiculus. Basically, it is a pathway of fibers that sort of looks like an arc. When you damage this structure the symptoms look very much like Wernicke's Aphasia except there are some subtle differences that can be detected with a variety of neuro psychological tests.

The next major structure in the telecephelon is what is called the occipital lobe and this is shown in slide fifty-three. The occipital lobe is primarily concerned with vision. It has several major structures as well. The first of these is what is called Area 17. This is what is called your primary visual cortex and where your visual information ends up from the thalamus and other structures. It also has a couple of other areas called Areas 18 and 19. These help with the organization of visual stimuli and then ultimately information from all these different structures is sent to other lobes for integration and processing.

A final major structure in the telecephalon which I did not have listed in earlier slides that is called the Island of Reil. As we can see in slide fifty-four the Island of Reil is also called in some anatomical texts the Insular Lobe. It is located under the lateral Sulcus and is primarily concerned with memory and the processing of information. It may also have a function with smell.

In conclusion, as we see in slide fifty-five, the brain has lots of structures. Each structure has lots of functions and in general the brain is very resistant to damage. However, when you do damage the brain individuals can have lots and lots of problems. However, the problems can also identify where the brain is damaged and then with retraining you can be helped.

Well that concludes this section of the physiological overview. In our next section we will begin talking specifically about nerve cells. So until then we hope you have yourself a great day and we look forward to talking with you soon.