Hypothalamus _____________________________________________________
The hypothalamus is located in the middle of the base of the brain and encapsulates the ventral portion of the third ventricle. It is the part of the brain that lies below the thalamus. As you will see, it is a region of the brain that controls an immense number of bodily functions such as bodily temperature, certain metabolic processes and other autonomic activities.
CRITICAL POINT: The Hypothalamus is the control center of all autonomic regulatory activities of the body. It has been said that the hypothalamus is the brain of the brain. It is the hub for automatic and endocrine homeostatic systems such as cardiovascular, temperature, and abdominal visceral regulation. It manages all endocrine hormonal levels, sensory processing, and organization of body metabolism. It appears that almost everything the Hypothalamus does is related in some way to the management of brain and body connection, linking the psyche (mind) to the body.
- Temperature Regulation As aforementioned, the hypothalamus is responsible for temperature regulation. Actually, it works the same way that the thermostat on your living room wall works. For example, let’s say you set your home thermostat at a temperature of 75 degrees. Okay, let’s say it starts snowing outside.
Eventually, your home temperature is going to drop below 75 degrees. What is going to happen now? If you said the heater is going to come on you win a red star. In truth, the heat is going to come on and stay on until the temperature in your home goes back up to 75 degrees. Let’s say it stops snowing and the sun comes out and starts beating down on your house. Naturally, the temperature of your house is going to go up. As soon as it goes above 75 degrees, the air conditioner is going to come on to cool the house down. Needless to say, the air will stay on until the house gets back to the 75 degrees that you set the thermostat at. Isn’t that neat the way it works? CRITICAL POINT: The body keeps its core temperature constant at about 37 C by physiological adjustments controlled by the hypothalamus (Thermostat Center) where there are neurons sensitive to changes in skin and blood temperatures. The temperatureregulating centers are found in the the anterior portion of the hypothalamus (Preoptic Area). This area receives input from temperature receptors in the skin and mucous membranes (Peripheral Thermoreceptors) and from internal structures (Central Thermoreceptors), which include the hypothalamus itself. The temperature sensory signals from preoptic area and those form the periphery are combined in the posterior hypothalamus to control the heat producing and conserving reactions of the body. The hypothalamic thermostat works in conjunction with other hypothalamic, autonomic and higher nervous thermoregulatory centers to keep the core temperature constant. Guess what, you have one of those thermostats in your head that works basically the same way. Only the thermostat in your head is set at 98.6 degrees, not 75 degrees. It is called the hypothalamic thermostat. Okay, I said that your hypothalamic thermostat is set at 98.6 degree. Now, let’s say you go outside and it starts snowing. If your surroundings are cold, your body temperature is going to drop. What is going to happen now? Don’t say you are going back into the house and get a coat. You can say that, but you are not going to get a red star for that answer. What is going to happen is your heater is going to come on. First of all, your skin, more specifically your pours, is going to contract and your hair is going to pilo-erect. In short, your hair is going to stand up and out. In laymen’s terms, you are going to get goose bumps or chills. Your extended hair will trap warm air to your body in an attempt to keep you warm. Did you ever see a dog on a cold day? He looks like a porcupine. His hair is straight out. This is how he keeps warm on a cold day. Next, your blood vessels will vaso-constrict, bringing warm blood to the core of your body and thereby keeping your internal organs warm. Finally, you will start shivering. When you shiver, the muscle cells rub together causing friction and heat. These physiological responses will persist until your body temperature rises back up to 98.6 degrees. Basically, that is how your heater works.
CRITICAL POINT: When the environmental temperature decreases gradually (ex. summer to fall), the hypothalamus releases Thyrotropin Releasing Hormone which activates the anterior pituitary gland to release Thyroid Stimulating Hormone (TSH). TSH induces the thyroid gland to liberate large amounts of thyroid hormone (T3 and T4) into the blood. Thyroid hormone increases metabolic rate, which increases the amount of body heat production. As the body gets warmer, the hypothalamic sensors detect the warmth and diminish the heat producing and heat loss prevention responses. Now, let’s say it stops snowing and the sun comes out and beats down on you. Your temperature is now going to go up, and then your air conditioning unit is going to come on. First, your blood vessels are going to vaso-dilate in an attempt to give off body heat through radiation and conduction. Next, you are going to start sweating to cool your body down and get rid of heat through evaporation. Just like with your cooling mechanisms, these physiological conditions will persist until your body temperature goes back to 98.6 degrees. That is essentially how your hypothalamic thermostat works. That wasn’t so bad, was it? Don’t answer that question. CRITICAL POINT: When the body is exposed to heat (sun, fire, too much clothing), body temperature rises. Skin warmth receptors and blood convey these changes to the hypothalamic thermostat. The thermostat inhibits the adrenergic activity of the sympathetic nervous system, which control vasoconstriction and metabolic rate, thus causing cutaneous vasodilatation and reducing BMR. This causes an increase in heat loss via the skin and a decrease in heat production in the core. If the heat is sufficiently intense, the cholinergic sympathetic fibers, which innervate sweat glands release ACH, stimulating sweat. Sweating is the most effective involuntary heat fighting response in man. Behavioral responses to heat, such as lethargy, resting or lying down with limbs spread out, decreases heat production and increases heat loss. If you think you are so smart figure this out. When I was a little boy, about two weeks ago, I came down with a disease called German measles. My body temperature was 104 degrees, but I was shivering like crazy and I had goose bumps from head to toe. My blood vessels had also vaso-constricted. Although I was burning up, my body was continuing to produce heat. What was all that about? Perhaps you have had a similar experience where you had a fever and your body was in a heat-producing mode. What happens in cases like this is that the invading antigen (virus or bacteria) attacks the hypothalamus and resets the thermostat to an elevated level…say 110 degrees. Like your home thermostat, your body will respond directly to the setting of your thermostat. Consequently, although your body is burning up and on the road to heat stroke and death, it will continue to produce heat until the thermostat setting is reached. In an attempt to lower the body temperature, doctors will pack the body in ice…at least that was what they use to do. Today, they have drugs that can lower the hypothalamic thermostat. Anyway, back to me. For three days my body temperature was hovering at 104 degrees. Then, the fourth day my doctor walked into my room, took one look at me and said, “Don’t worry, you are going to be all right.” How in the world did he know that? He never examined me, never touched me and he never even came near me. How did he know I was going to be okay? I will tell you how. He noticed that I was sweating. What did that tell him? It told him that my hypothalamic thermostat was back in order because now my air conditioner was back working. You probably heard people say, “He broke the fever.” Well, that is what they are talking about. See, you learn everything here.
- Appetite Perhaps the best way to understand how the hypothalamus affects appetite is to once again use the little man or the homunculus analogy we discussed in the introduction. Let’s do it this way. You go over
to McDonald’s restaurant and order one of those ninety nine cent Big Macs that sells for five dollars nowadays. You know the kind…two all beef patties, special sauce, cheese, pickles, lettuce, onions, on a sesame seed bun. You take a big bite and chew it up into this icky substance called bolus. This process is called mastication, not masturbation, as many of my students seem to think. Evidently, many of them are working on the wrong end most of the time. CRITICAL POINT: It appears that almost everything the Hypothalamus does is related in some way to weight management and controlled weight loss. Most simply, when the Hypothalamus is damaged," food becomes increasingly more important, but increasingly more unfulfilling. We end up never feeling satisfied with the foods which we have eaten, gradually eating more and more to try to compensate for whatever is lacking! From a metabolism stand point, the Hypothalamus not only governs the motivation to eat, stimulating hunger and appetite, but most importantly how eating is to be experienced and reflected upon, whether it is satisfying or not, and how deep the satisfaction occurs. Anyhow, after you chew your food up, you swallow it and it goes down into your stomach where it is churned up into this gummy substance called chime. Your pancreas then squirts out hydrochloric acid that breaks the chime down to a complex sugar called glycogen. The glycogen is then converted to a simple sugar called glucose and the glucose is circulated through the body by way of your blood stream. The pancreas then secretes insulin, which gives the cells of the body the ability to absorb the glucose. Here is something you may not know. Every cell in the body has a manufacturing company called mitochondria. Once the cell absorbs the glucose, it is taken to this manufacturing company and converted into an energy rich compound: Adenosine tri-phosphate (ATP). It is ATP that actually serves as the fuel for the cell’s energy requirements. ATP molecules represent stored chemical energy and when the bonds of the ATP molecules are broken, energy is released. The breakdown of ATP serves to power all biological work. Isn’t that neat? CRITICAL POINT: ATP molecules represent stored chemical energy and when the bonds of the ATP molecules are broken, energy is released. The breakdown of ATP serves to power all biological work. In brief, nutrients in consumed food supply the energy that powers all biological functions, but in order for the cells (which are like chemical factories) to use these nutrients, they must first be converted to ATP and then oxidized. If you understand all of that raise your
hand. Too bad, we are going ahead away. Okay! Okay! I will wait…go back and read it again you big Dummy. Now that you know all of that, let’s back up a little. Once the food is converted to glucose, the glucose is dumped into the blood stream. The blood in turn carries the glucose throughout the body and passes it on to the cells so that it can be used for energy. You should remember that too. We just talked about it…the pancreas secretes insulin, cells absorb the glucose, mitochondria converts it to ATP, ATP molecules are broken down and energy is released. I know…go back and read it again. It is important. So make sure you understand it. Go ahead, I will wait here for you. Now, here is the point I am trying to make. It is the glucose or sugar concentration level of the blood that offers the first clue as to why we experience the sensation of hunger. Research has revealed that when an individual’s blood sugar level drops, his appetite will increase significantly. When his blood sugar level is increased, his appetite will decrease significantly. Apparently, there are sugar detectors in the body that let your brain know how much sugar is in your blood. Where do you think those receptors are located? Recent studies have revealed that the liver and the hypothalamus contain such sugar detectors. However, it seems that the sugar detectors in the hypothalamus have the greatest impact on hunger. CRITICAL POINT: Research has revealed that when an individual’s blood sugar level drops, his appetite will increase significantly. When his blood sugar level is increased, his appetite will decrease significantly. Using the homunculus analogy, try to envision a little man sitting on the top of your hypothalamus operating a panel with two switches. The switch on his right (actually the lateral portion of the hypothalamus) activates the satiation center. Sure enough, when he hits that switch, your hunger is…well, satiated. The switch on his left (the ventral medial portion of hypothalamus) activates the feeding center. As you might expect, if the feeding center is switched on, your hunger will increase. What determines which switch is turned on is the glucose concentration level of the blood. As the blood passes by the hypothalamus, our “little man” sticks his finger in the blood and tastes it. If the blood has a lot of sugar and/or glucose in it, the “little man” will turn off the switch controlling the feeding center and flip on the satiation switch, thereby decreasing biological hunger. On the other hand, if there is very little sugar in the blood, the “little man” will do the opposite. He will switch on the feeding center and flip off the satiation center and bring about the sensation of hunger. To a large degree, appetite is contingent upon the glucose concentration level of the blood. There is considerable research to substantiate the hypothalamic theory of eating. For instance, numerous studies have shown that when the lateral hypothalamus (feeding center) of a rat is destroyed, the animal will refuse
to eat and will actually starve to death unless it is force fed. Conversely, research consistently indicated that if a rat’s ventral medial area of the hypothalamus (satiation center) is destroyed, the animal will develop a voracious appetite. He will eat excessively and can end up almost tripling his body weight in a very short period of time. Along these same lines, research concerned with electrical stimulation of the brain consistently revealed that stimulation of the feeding center will cause hyperemia (abnormal hunger), while stimulation of the satiation center will cause anorexia (loss of appetite). CRITICAL POINT: Research concerned with electrical stimulation of the brain consistently revealed that stimulation of the feeding center will cause hyperemia (abnormal hunger), while stimulation of the satiation center will cause anorexia (loss of appetite). Early studies have also shown that when the blood from a satiated dog was transfused into a starving dog, the starving dog would not eat food that was placed in front of him. Conversely, when the blood from a starved dog was transfused into a dog that had just finished eating all it wanted, the dog would start to eat again. All in all, these studies certainly seem to indicate that the glucose concentration in the blood plays an important role in satiation and hunger. Now we know that a low glucose concentration blood level can turn on the feeding center and turn off the satiation center, thereby causing you to become hungry. We also know that the reverse will occur if we elevate the glucose concentration level of the blood. It would seem then, that the only thing you would have to do to decrease hunger is to monitor the glucose concentration level of the blood. Sounds easy, right? Wrong! CRITICAL POINT: Studies certainly seem to indicate that the glucose concentration in the blood plays an important role in satiation and hunger. First of all, when you start eating, the glucose concentration level of the blood is not immediately or dramatically affected. For instance, if you ate a bowl of pasta, it would take anywhere from two to four hours for the pasta to be digested and assimilated into your bloodstream. Obviously, we stop eating long before the food we eat affects the glucose concentration level of the blood. If we didn’t, we would find that every time we sat down for a meal, we would eat for hours. In other words, a low glucose concentration level in the blood is quick to turn your hunger on, but there are other physiological mechanisms besides the high glucose concentration level of the blood that turns your hunger off. One of those physiological mechanisms is a “swallow counter”. Research indicates that there is some part of the hypothalamus that actually counts how many
times an individual chews and swallows. After a certain number of chews and/or swallows, the satiation center is activated and the feeding center is shut off. Obviously, this occurs long before the glucose concentration level of the blood is elevated. Thus, it seems that hunger can be satisfied to some extent by chewing and swallowing. It is believed that the trigeminal nerve that runs from the lips and cheek to the satiation center in the hypothalamus is the body’s “swallow and chewing counter.” Supposedly, the trigeminal nerve sends sensory impulses to the satiation center every time the individual chews and swallows. After a number of stimulations, the satiation center apparently switches on and thereby decreases hunger. CRITICAL POINT: The trigeminal nerve that runs from the lips and cheek to the satiation center in the hypothalamus is the body’s “swallow and chewing counter.” Evidently, the trigeminal nerve sends sensory impulses to the satiation center every time the individual chews and swallows. Although the swallow counter gives us some insight as to how appetite is decreased without elevating the blood glucose level, it doesn’t give us the entire answer into this complex physiological system. As you might expect, your stomach plays a big part in your desire to eat. What you may not know is that your stomach is a pretty smart organ. As mentioned, when food enters the tummy, it is churned around and squeezed into a ball by the muscles of the stomach. If you eat at the same time every day, your feeding center and other parts of your brain will learn to anticipate when food is coming. To prepare for the anticipated food, the brain sends messages to the stomach about an hour before feeding time so the stomach can get its muscles ready to perform. In response, the muscles of your stomach begin to churn, thereby signaling that you are getting hungry. The closer it gets to your normal eating time, the more your stomach growls and consequently, the hungrier you feel. If you don’t eat, the stomach will continue to contract as if food was actually present. This churning and squeezing of the stomach muscle will eventually lead to what is commonly called hunger pangs. Interestingly, if you can get through your normal eating time without taking in any food, your hunger pangs will subside just as if you’ve eaten a full meal. However, hunger pangs will again show up. This is a learned phenomenon. That’s right. Your brain and stomach actually learn to function on cue. In other words, you’ve actually taught your stomach and/or yourself to become hungry during certain times of the day. On the brighter side, any behavior that is learned can be unlearned and replaced with new learning. In this particular case, relearning is a snap. All you have to do is stagger your meal times. One day eat on the hour, the next day eat fifteen minutes before the hour, the following day eat fifteen minutes after the hour and so on. Once you control the hunger signals from your stomach, you should find it a little easier when you diet. There is one more point here that I have to make. A lot of people think that the stomach stretches and shrinks. Actually, some of those brilliant professors who have a lot of letters behind their names believe this. Well, don’t let that fool you because degrees and titles mean absolutely nothing in America. Some of the dumbest people I have ever met have a Ph.D. behind their name and some of the smartest
people I ever met don’t even know what a Ph.D. is. Believe me, anyone can get a Ph.D. Heck, I got one. That is just some free advice. Anywho, those guys who believe the stomach stretches are not even close. The stomach is made of smooth muscles. Consequently, it cannot stretch or shrink. However, the stomach does have a series of receptors throughout its lining that are sensitive to food volume. Again, it’s like having a little man down there that checks the volume of food coming into the stomach. When the volume reaches a certain level, the little man in the stomach calls up to his buddy in the hypothalamus and tells him to flip on the satiation button and flip off the feeding button. The volume of food in your stomach also plays a major part in controlling hunger. Here is the thing though. The receptors and or the little man can be taught how much food is necessary to satiate hunger. If you eat large meals, the little man (receptors) in your stomach will learn that a large volume of food is necessary to satiate hunger. If you eat small meals, the little man will eventually come to the conclusion that less food is necessary to satiate hunger. In short, you can actually teach the little man how much food is necessary to satiate hunger. CRITICAL POINT: The stomach has a series of receptors throughout its lining that are sensitive to food volume. On that account, all you have to do to control biological hunger is to eat small meals throughout the day in order to keep a constant glucose concentration level. Chew your food thoroughly and swallow a lot to activate your trigeminal nerve. Eat small portions of food in order to teach your stomach that not much food is required for satiation and stagger your meal times so that your stomach will learn when food is coming. If you do all those things, you will be able to control your biological hunger. The problem is that most America’s don’t eat because they are hungry. However, that is another discussion. In order to help an obese individual lose weight, I contend that you have to teach them to be aware of both his internal and external environment. In a nutshell, you have to look at hunger as both a biological and psycho-sociological experience. But I am not writing a book on that…well, actually I did. It’s called Extreme Shape. If you want to know how to control both your internal and external environment, go buy that book…you are not getting everything for free here. Okay, I will give it to you free, but you will have to read to the end of the chapter to get that information…see I am not all bad.
- Water Balance The hypothalamus also regulates intercellular water balance. As you are probably aware, every cell in your body has an intercellular fluid…fluid that is inside the cell. This fluid is maintained by a ratio of salute molecules to water molecules. Simply put, for every one solute molecule inside the cell you have three water molecules. For example, if you had two salute molecules, then you would have six water molecules. If you had three salute molecules, then you would have nine water molecules. Naturally, you have many more solute and water molecule than that, but I am just trying to give you the idea. You have to sustain that ratio to maintain homeostasis in the cell. For instance, if a solute molecule is added, then three water molecules have to be added. Conversely, if a solute molecule is taken out, then three water molecules have to be taken out.
CRITICAL POINT: Thirst occurs when the hypothalamus, sense that our blood is becoming to concentrated, this signifies that we don't have enough liquid in our blood. This is called an increase in plasma osmolality, and it is detected by the hypothalamus. This gives us a conscious awareness of thirst. Did your mother ever make you ham for Christmas? Typically, after you eat the ham, a few hours later you are dying of thirst. Why? Because ham has a high solute and/or sodium concentration, the cells take on the solute. In order to maintain the ratio of solute to water, you have to drink more water. The opposite effect occurs when you drink beer. Did you ever notice when you drink a lot of beer you are always in the restroom urinating? You might as well just go into the bathroom and pour the stuff down the toilet and eliminate the middleman. Why are you constantly urinating when you drink beer? The answer is simple. Beer is a strong diuretic which draws solute out of the cells. If you take the solute out, the water has to follow so that the cell can maintain the proper ratio of solute to water. That is how all diuretics work. Have you ever read the poem The Rhyme of the Ancient Mariner? Here is this guy standing on the bow of a boat dying of thirst and he says, “Water, water, everywhere and not a drop to drink.” Is this guy nuts or something? There is water all over the damn place. Why doesn’t he drink it? If you said because it’s salt water, you get another red star. Don’t get all excited. I give those stars to everyone. The reason the guy can’t drink the salt water is because the ratio of solute to water is about 10 to 1. By drinking the salt water, he will dehydrate the cells and kill himself…a not so good thing. CRITICAL POINT: Thirst also occurs when areas of our blood vessels detect that we don't have enough blood circulating or our blood pressure is too low. Special parts of our blood vessels send signals to our hypothalmus and help to stimulate thirst. These special areas of the blood vessels are called Baroreceptors (Baro = Pressure). Our kidneys detect low blood volume and osmolality as well and release factors that cause thirst behavior and water intake and conservation. Here is something that might interest you. In 1987, my coach called me and said he wanted me to fly to Gettysburg, Pennsylvania to watch a powerlifting meet. He said that the Russians were going to compete there and he wanted me to see what kind of lifters they had. So I jumped into a plane and went to Gettysburg. When I got there my coach told me that he wanted me to lift in the meet because they were going to send the winners to West Germany to compete. I told him I would love to compete, but that my body weight was 141 and I could never make the 132 pound weight class. He said, “There is a doctor here who is going to give you a shot of Lasix…you will make the weight.” To be honest, at the time I didn’t even know what Lasix was, but in order to humor my coach, I let the doctor give me an injection of 120 milligrams of Lasix. After the doctor gave me the shot, I looked at him and said, “What now?” He replied, “Go over there and go to the bathroom.” I told him I didn’t have to go. He said, “Just go over there and try.” So I went over to the urinal and stood there for a few moments. Then all of a sudden, I started urinating and urinating and urinating. I urinated so much that I actually got tired standing there. Actually, I was wondering if I would ever stop. When it was all said and done, I dropped my body weight from 141 pounds all the way down to 130 pounds. I looked like a dried-up prune. I was totally dehydrated. How did that work? Simple, Lasix is a very powerful diuretic and as mentioned, diuretics pull solute out of the cells. When solute goes, so does the water. The more solute you pull out, the more water you give off.
CRITICAL POINT: Diuretics are medicines that aid the elimination of sodium (salt) and water from the body. Diuretics act by increasing the excretion by the kidneys of sodium in the urine. When the kidneys excrete sodium, they excrete water from the blood along with it. That decreases the amount of fluid flowing through the blood vessels, which reduces pressure on the walls of the arteries. One reason these drugs are used to control High blood pressure.
- Pleasure and Pain We now know that there are pleasure centers throughout the brain, but one of the more pronounced centers is in the hypothalamus. Investigating the pleasure centers in the hypothalamus, two researchers, James Olds and Peter Milner, rigged up a small rat-sized box with a single metal lever. The lever was connected to an electrical stimulator so that every time the rat pressed the lever, the animal stimulated pleasure center in his hypothalamus. As soon as the rat figured out that he could experience pleasure by pressing the lever, he just about wore the lever out. He banged away at the lever as often as one hundred times a minute. Amazingly, the rat continued pressing the bar hour after hour until he collapsed from euphoric exhaustion. Then, he slept for a few hours, but as soon as he woke up and regained his strength, he was right back on the lever. It wasn’t just this single rat that responded that way either. Every single time they repeated the experiment, the rats responded exactly the same way.
∞ DRUGS in Perspective ∞ __________________________________________________________________
Cerebellum: A bundle of neurons responsible for coordination and kinesthetic movement. Cerebral Cortex: The outer gray matter covering each hemisphere of the brain. It has a motor and speech center, visual, olfactory, and auditory parts. Cerebral hemispheres: The two halves of the globe-shaped cerebrum. Cerebrum: The big, thick cap on top of your brain. Most of your important mental function takes place in your cerebrum. Corpus callosum: The bridge of nervous tissue that connects the major and minor hemispheres. Endrophins: Morphine like substances that are produced and released naturally in the body. Enkephalins: Morphine like substances that are produced and released naturally in the body. These substances influences the way pain messages a received and transmitted. External locus: The belief that the individual has no control over his behavior or destiny. Internal locus: The belief that you have control over your own behavior and destiny; also referred to as internalizers. Homeostasis: An organism’s or cell’s ability and/or tendency to maintain an internal equilibrium through physiological process adjustment; an internal state of optimal normal function.
CRITICAL POINT: The hypothalamus helps regulate pain and pleasure. Now, this may interest you. In my introduction psychology class at the University of Georgia, each of the students in the class were required to use “shaping” to teach a mouse to perform some type of skill. Simply put, shaping is the reinforcement of small bits of behavior to get a desired response. What we would do is starve our mouse half to death and then use food to reinforce the behavior we wanted. Not surprisingly, with food as the reinforcer, we could only work with our mouse for about only twenty minutes before he was satiated. Then we would have to wait for a few hours until he was starving again before we could work with him. Most of the students would spend the entire semester trying to teach their mouse some simple skill like running a simple little maze. Well, do you know what I got my mouse to do? I had him start off upstairs in a bed in this little dollhouse. Then, I had an alarm clock go off. The mouse would get out of bed, run down stairs and go over to a little tape recorder. He would push the start button and the Star Spangle Banner would start playing. He would then run outside to a little flagpole, pull up the American flag and then stand at attention until the Star Spangle Banner was over. Then, he would take the flag back down, run back into
the house, back upstairs and go back into bed. When the rest of my classmates and my teacher saw that they were flabbergasted. They couldn’t believe I taught my mouse all of that in one semester. How did I do it? Well, I cheated kind-of sort-of. A friend of mine, Dr. Arny Ferrando, who was doing animal experiments with electrical stimulation of the brain helped me out a little. I had him implant an electrode in the pleasure center of a mouse’s brain that I could activate with an electrical stimulator. Every time I pressed the remote control, the mouse would experience extreme euphoria…kind of like an orgasm. At least that is the way Arny described what the mouse was experiencing when I pressed the stimulator. I always wondered how he knew that. Anywho, you know what some guys will do for an orgasm…well, a mouse will do about the same thing…only more so. With the electrode in my mouse’s brain, I could work with him for hours on end. I couldn’t tire the darn thing out. With in less than a month I had accomplished something that would have taken my classmates a year or more to achieve. CRITICAL POINT: Injury to the hypothalamus has been associated with imbalances in pain and pleasure, with patients becoming confused and switching frequently between one and the other. Areas that used to respond to pleasurable stimuli can spontaneously start feeling pain and vice versa. Here is something else you might find interesting. Some long distance runners exhibit characteristics of true addiction. That is, they run in order to get what has become known as a “running fix.” The fix or euphoric feeling that the runner experiences is thought to be brought about by endogenous morphine-like substances (endorphins) that are naturally secreted in the body. It has been hypothesized that when a runner pushes himself to the point of pain, the nervous system, more specifically the hypothalamus, is stimulated to release additional endorphins. Also of interest is that Brian Goldstein, a world renowned physiologist, recently discovered brain endorphin to be more than two hundred times as powerful an analgesic as morphine. Since endorphins are like morphine, not only is the runner’s pain eased, he also experiences a type of drug high. Some runners who are kept from running will actually experience withdrawal symptoms including depression, insomnia, decreased appetite, tics and irregularity. Long distance runners who run on the average of seventy five or more miles a week have the greatest risk of becoming exercise addicts.
Female Reproductive System _________________________________________________________
Before we can get a clear understand as to how the hypothalamus is integrated with the female reproductive system, we will first have to check out her anatomy. I don’t know about you, but I am all for that…Ahhh!...that’s not sexual harassments it...because I am trying to cut back. First, we are going to have to do a laparotomy. Well, first we are going to have to find a female, but just use your imagination until then. In case you didn’t know, laparotomy is the opening of the stomach wall. Otomy means to open, and lap is the prefix for stomach. Once we get inside there, we are going to look specifically at the reproductive organs. We will start with the vagina…can you think of a better place to start? Okay,
moving right along, the vagina leads to the cervix, which is the mouth of the uterus. The uterus or womb is composed of two linings…the myometrium, which is a very powerful muscle and the endometrium, which is very vascular. The endometrium is where the zygote attaches. At the top of the uterus, fallopian tubes lead out of the uterus and down to the ovaries. At the end of the fallopian tubes there are finger like extensions called the fimbra. The fimbra are used to sweep the ovum that is released by the ovaries into the fallopian tubes. CRITICAL POINT: The female reproductive system (or female genital system) contains two main parts: the uterus, which hosts the developing fetus, produces vaginal and uterine secretions, and passes the male's sperm through to the fallopian tubes; and the ovaries, which produce the female's egg cells. Around the eighth or ninth day of a female’s menstrual cycle, her hypothalamus will start secreting releasing factors. A releasing factor is not a real hormone, but rather a hormonal messenger…you know, a releasing factor. The first releasing factor it produces is follicle stimulating hormone releasing factor (FSH-RF). When FSH-RF is released from the hypothalamus, it goes to the pituitary gland by way of the blood stream. The FSH-RF activates the pituitary gland to produce the actual hormone FSH. The FSH is then released and by way of the blood stream goes to the ovaries. The FSH causes anywhere from 2 to 32 follicles to start growing and nurturing. This is called the follicular phase of menstruation. A few days later, the hypothalamus will start producing another releasing factor called luteinizing hormone releasing factor (LH-RF). Again, this is just a releasing factor. Once released, the LH-RF goes to the pituitary by way of the blood stream and cause just one of those initially activated follicles to grow bigger, and bigger, and BIGGER…until it eventually bursts. When it burst, an egg or an ovum is released. This is called ovulation. CRITICAL POINT: The vagina is a fibro muscular tubular tract leading from the uterus to the exterior of the body in female. The vagina is the place where semen from the male is deposited into the female's body at the climax of sexual intercourse. Around the vagina, pubic hair protects the vagina from infection and is a sign of puberty. Once upon a time, that’s right, this is a use your imagination story, there was an Italian gynecologist who was doing a laparoscopy at the exact time that this woman he was studying ovulated. He noticed that the follicle that released the ovum was yellow. Therefore, he called the follicle a corpus luteum, which means yellow body in Italian. He also noticed that there where hormones oozing from the corpus luteum. He traced the hormone through the body and found that it went to the endometrium and caused it to build up with blood and nutrients. This hormone was preparing the endometrium to for pregnancy. When he saw that, he called the hormone progesterone, which in Italian means prepare for
pregnancy. Then, he noticed that the corpus luteum was producing another hormone. He traced that one through the body and he found that it went to the hypothalamus. When it came in contact with the hypothalamus, it stops the hypothalamus from producing FSH-RF and LH-RF. Briefly, it was an inhibitory hormone. He called this hormone estrogen because estrogen in Italian means…well…nothing…so he just made the word up I guess. CRITICAL POINT: The cervix is the lower, narrow portion of the uterus where it joins with the top end of the vagina. It is cylindrical in shape and protrudes through the upper anterior vaginal wall. Approximately half its length is visible, the remainder lies above the vagina beyond view. He also noticed that estrogen went to the girl’s breast and bootie and caused these sites (estrogen receptors) to start accumulating subcutaneous tissue (a functional fat tissue), bringing about the development of the females…well, breast and bootie. HURRAY! In a word, he found that estrogen was not only an inhibitory hormone, but it was also responsible for the secondary sex characteristic of the female. CRITICAL POINT: The uterus or womb is the major female reproductive organ of humans. The uterus is a pear-shaped muscular organ. Its major function is to accept a fertilized ovum which becomes implanted into the endometruim, and derives nourishment from blood vessels which develop exclusively for this purpose. The fertilized ovum becomes an embryo, develops into a fetus and gestates until childbirth. Let’s get back to that ovulation part. The corpus luteum releases the egg and the fimbra sweep it up into the fallopian tube. Meanwhile, the woman goes over to her boyfriend’s house and gets her brains banged out. She gets these big knots on the back of her head from hitting the headboard and then the guy ejaculates. You know what that means…child support. The guy’s little sperms go swimming upstream and then one of them hits pay dirt. The sperm unites with the egg and now you have gestation. The consequence of which is a zygote. The zygote travels down the fallopian tube and eventually embeds into the wall of the uterus, more specifically, the endometrium. As soon as the zygote embeds into the uterus, it starts producing two hormones of its own. The first one is gonadatropin hormone. Once produced, gonadatropin hormone goes to the corpus luteum and tells it to keep producing estrogen and progesterone. Why do you think this is important? I will tell you why…because progesterone is necessary to keep the endometrium viable. Without progesterone, the lining will begin to flake off and the zygote will be aborted. The real thought provoking question is…why the estrogen? In all candor, it is not that thought provoking. The estrogen is necessary to inhibit the hypothalamus from secreting FSH-RF and LH-RF. If the hypothalamus would continue to secret those releasing factors, the women would continue to ovulate and she could end up with multiple pregnancies. In a nutshell, by producing gonadatropin hormone, the zygote is watching out for itself by ensuring that the endometrium remains intact and that no more ova will be released while he is in house…in the uterus. Here is something else that is pretty neat. The zygote will also produce the hormone prolactin. Prolactin goes to the woman’s breasts and causes them to build up with milk. This is called lactation. The woman’s breasts enlarge and everyone is happy…well, at least the zygote and boyfriend are. In this case, the zygote is ensuring that he will have something to eat once he is born. CRITICAL POINT: The fallopian tubes or oviducts are two very fine tubes leading from the ovaries of female into the uterus. On maturity of an ovum, the follicle and the ovary’s wall rupture, allowing the ovum to escape and enter the fallopian tubes. There it travels toward the uterus, pushed along by movements of cilia on the inner lining of the tubes. This trip takes hours or days. If the ovum is fertilized while in the fallopian tubes, then it normally implants in the endometrium when it reaches the uterus, which signals the beginning of pregnancy
Okay, now let’s get real. You know that no woman is going to have sex before she is married because sex before marriage is a sin. And women never commit sins. If you don’t believe me, ask them. Consequently, that means no knots on the back of her head. Without the knots on the back of her head, there will be no sperm in her fallopian tubes. No sperm, no zygote, no zygote no prolactin, no prolactin, no lactation, and the girlfriend’s breasts stay teeny weenie. No zygote, no gonadatropin, no gonadatrophic and the corpus luteum withers and dries up. No corpus luteum, no progesterone, no progesterone and the endometrium starts flaking off and the woman begins to menstruate. No corpus luteum, no estrogen, no estrogen and the hypothalamus starts to produce the releasing factors and the whole mess starts all over again. Isn’t that incredible? Of course, it is. CRITICAL POINT: The ovaries are small, paired organs that are located near the lateral walls of the pelvic cavity. These organs are responsible for the production of the ova and the secretion of hormones. Ovaries are the place inside the female body where ova or eggs are produced.
Now, can you tell me how the birth control works? Sure you can. There are basically two types of pills: the sequential pill and the combination pill. Both pills work basically the same way, so let’s just look at one of them. Let’s look at the sequential pill, which is the more commonly used medication. The sequential pill contains two hormones: estrogen and progesterone…how about that? The first 15 days of the pill is almost pure estrogen. Of course, the estrogen knocks off the hypothalamus. As a result, the hypothalamus does not produce any FSH-RF or LH-RF. Without the FSH-RF and LH-RF, the pituitary gland won’t produce any FSH or LH and then the woman won’t ovulate. If the woman doesn’t ovulate, there is no ovum. Without the ovum, there can be no pregnancy. CRITICAL POINT: The process by which the ovum is released is called ovulation. The next 6 days the pill is almost pure progesterone. Now, here is the real stumper…why is there progesterone in the pill if the woman isn’t going to get pregnant? She certainly doesn’t need to have blood and nutrients in her uterus if there is not going to be a zygote in there. To be honest, there really is no need for progesterone in the pill except for one little thing. What is the first symptom of pregnancy? If
you said no menstruation, you get another red star. Progesterone is necessary for the endometrium to build up with blood and nutrients. Without progesterone, there would be no blood in the uterus. Thus, the women would not menstruate. If she didn’t menstruate, every month she would have to be running back and forth to the doctor to see if she was pregnant. The last seven pills are placebos…they are in essence sugar. There is nothing in them. You don’t even have to take them if you don’t want to. The only reason they are in there is to keep you on track so that you don’t forget when to take the estrogen and progesterone pills. When you are taking these placebo pills though, the progesterone blood level drops and you know what that means…the endrometrium without progesterone starts flaking off and the woman menstruates. WOW!!!!!!!!! I am glad that is over with. Don’t get too excited though, we still have the male reproductive cycle to check out.
Male Reproductive System _____________________________________________________________________________
All right, let’s look at the male reproductive system. To do this we will need to cut open someone’s testicle and it’s not going to be mine. So we are going to need another one of those mandatory volunteers. What the heck, we will use my dean again. He doesn’t use his testicles any more than he uses his brain. Don’t tell him I said that.
CRITICAL POINT: The penis is the male organ used in sexual intercourse. It has three parts: the root, which attaches to the wall of the abdomen; the body, or shaft; and the glans, which is the cone-shaped part at the end of the penis. The opening of the urethra, the tube that transports semen and urine, is at the tip of the penis. The body of the penis is cylindrical in shape and consists of three circular shaped chambers. These chambers are made up of special, sponge-like tissue. This tissue contains thousands of large spaces that fill with blood when the man is sexually aroused. As the penis fills with blood, it becomes rigid and erect, which allows for penetration during sexual intercourse. Okay, we are going to take his testicle out of his scrotum and then cut it lengthwise. OUCH! At the bottom of the testicle you will see a series of convolutions. This is his seminiferous tubules. The seminiferous tubules are the part of the testicles that produce sperm and testosterone, the male hormone.
We will get to that in a second. When sperm is produced, it is stored in a small compartment just above the seminiferous tubules called the epididymus. The sperm remains in the epididymus until needed. WINK! From the epididymus, sperm goes through a tube called the vas deferens. Have you ever heard of a vasectomy? Ectomy means to remove. So a vasectomy is the removal of the vas deferens…well, part of the vas deferens anyway. By clipping the vas deferens off, sperm is blocked from leaving the body when the male ejaculates. CRITICAL POINT: The scrotum is the loose pouch-like sac of skin that hangs behind and below the penis. It contains the testicles (also called testes), as well as many nerves and blood vessels. The scrotum acts as a "climate control system" for the testes. For normal sperm development, the testes must be at a temperature slightly cooler than body temperature. Special muscles in the wall of the scrotum allow it to contract and relax, moving the testicles closer to the body for warmth or farther away from the body to cool the temperature. Here is a question for you. If a man has a vasectomy, does he still ejaculate fluid? Of course he does. Fluid produced by the seminal vesicles is ejaculated. Naturally, there is no sperm in it because as mentioned, the sperm is blocked by the vasectomy. Anywho, the vas deferens leads into the urethra and from there…well, I am not at liberty to tell you that. Okay, now that we got a quick and crude overview of the male reproductive system, let’s take a closer look as to how it works. This is the important part, so pay close attention here. CRITICAL POINT: The testicles (testes) are oval organs about the size of large olives that lie in the scrotum, secured at either end by a structure called the spermatic cord. Most men have two testes. The testes are responsible for making testosterone, the primary male sex hormone, and for generating sperm. Within the testes are coiled masses of tubes called seminiferous tubules. These tubes are responsible for producing sperm cells. Here is something that might surprise you. From a hormonal stand point, men and women are very closely related. Just like in a woman, the male’s hypothalamus secretes releasing factors. The first releasing factor it produces is inter-cellular hormone release factor (ICH-RF). When ICH-RF is released from the hypothalamus, it goes to the pituitary gland by way of the blood stream. The ICH-RF activates the pituitary gland to produce the actual hormone ICH. The ICH is released and by way of the blood stream goes to the testicles, more specifically the seminiferous tubules. The ICH causes the seminiferous tubules to produce sperm. That is important to know. I will say it again. The ICH causes the production of sperm. A few days later, the hypothalamus will start producing another releasing factor. Guess what it is…luteinizing hormone releasing factor. That’s right, the same LH-RF that the females produce. Once the LH-RF is released, it goes to the pituitary by way of the blood stream and causes the pituitary gland to release the actually hormone LH. The LH then goes to the seminiferous tubules by way of the blood stream. The LH causes the seminiferous tubules to produce testosterone. That is also important to understand because we are going to use this information later on when we talk about steroids. Testosterone is both an anabolic and androgenic hormone, meaning that it promotes muscle growth and the secondary sex characteristics of males. Also, like estrogen, it is an inhibitory hormone. Once the blood level reaches 10 milligrams of testosterone, it knocks off the hypothalamus. Accordingly, the hypothalamus does not produce any LH-RF or ICH-RF. Without the LH-RF, the pituitary gland body won’t produce any LH or ICH and the testicles won’t produce any more testosterone or sperm. Here is another question for you. Could you develop a male birth control pill after what I just told you? Of course you could. All you would have to do is give him 10 milligrams of testosterone. That
would knock off the hypothalamus. As a result, no ICH would be produced. Without ICH, the male would not be able to produce sperm. Remember all of this because we are going to come back to it later.