dg-chapter 4 section 2 text

Why Do We Need Oxygen? ____________________________________________________________________________________

Why do we need oxygen? This is a question my students mull over in their brains hour after hour until the Madonna’s video come on MTV every night. Some of the answers I’ve gotten are…well… cute…things like “You need oxygen to breathe,” or “You need oxygen to make the blood go through the body.” Of course, the standard answer is “You need oxygen to live.” Yet, few students really understand why.

We are going to tell you why it is imperative that you get oxygen without embarrassing you. What the heck, you paid for the book so we are going to cut you some slack.

Let’s do it this way. You go over to McDonald’s restaurant and order one of those 99-cent Big Macs that sells for $2.50 nowadays. You know the kind…two all beef patties, special sauce, lettuce, cheese, pickles, onions, on a sesame seed bun. You take a big bite and chew it up into this icky substance call bolus. This process is called mastication. 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 your cells the ability to absorb the glucose.

CRITICAL POINT: Adenosine triphosphate (ATP) serves as the fuel for the cells’ energy requirements. ATP molecules represent stored chemical energy. Energy is released when the bonds of the ATP molecules are broken. The breakdown of ATP serves to power all biological work.

Now, here is something you may not know. Every cell in the body has a manufacturing company called mitochondria. Once this cell absorbs the glucose, it is taken to this manufacturing company and converted into an energy rich compound called adenosine triphosphate (ATP). ATP serves as the fuel for the cells’ energy requirements. ATP molecules represent stored chemical energy. Energy is released when the bonds of the ATP molecules are broken.

The breakdown of ATP serves to power all biological work.

CRITICAL POINT: Oxygen is necessary to break down adenosine triphosphate (ATP) So, what does this have to do with oxygen? I am glad you asked. Let’s use another analogy here. When it gets cold, we go out and chop wood to build a fire. The log goes into the fireplace and then we stand next to it. Now, does

that make us warm? Of course not! In order to get heat from the wood, the wood has to burn. Thus, the wood is potential energy, but it is worthless to us unless we can light it. Then, we get energy from the wood. ATP is like the wood. It is potential energy, but you can’t get the energy from it unless you light it.

And guess what lights it? Get a grip now because this is the $64 million question. If you said oxygen, you’re right. You win $64 million…use your imagination here. When oxygen mixes with ATP, a phosphate is released and used for energy! In short, nutrients in consumed food supply the energy that powers all biological functions. In order for the cells (which are like chemical factories) to use these nutrients, they must first be converted to ATP and then oxidized.

The Defense Mechanisms of the Cardiorespiratory System We need to understand just a few more things before we can look ∞ DRUGS in Perspective ∞ __________________________________________________________________ at how cigarettes can destroy your body. The major thing we have to Tar: Any of the solids found in tobacco smoke. look now is how the Sidestream smoke: Smoke released into the air from a lit cigarette. cardiorespiratory system defends itself from foreign matter. Don’t Snuff: Smokeless tobacco. stress out…this is going to be fun.

Surgeon General: The chief medical officer in the U.S. Public Health When I was in college, my Service or in a state public health service. father would go to great pains to get Cathinoids: Prototype of a series of synthetic drugs that have me summer jobs that were absolutely pronounced stimulatory actions on the central nervous system. horrifying. His idea was that once I Carcinogenic: Any of a number of agents that can cause cancer, experienced the backbreaking reality including chemicals, radiation, and viruses. Exposure to such of common labor, I would appreciate agents, singly or in combination, can initiate cancer under conditions not entirely understood. my college education a lot more. He was certainly right about that! I Relapse syndrome: A returning to the use of cigarettes or alcohol after mean, some of the jobs he got me quitting. would make picking cotton look like Toxicity: The capacity of a drug to damage or cause adverse effects to the a white-collar job. body.

One summer I’ll never forget Passive smoking: Is the condition by which a nonsmoker is forced to is when he got me a job at the inhale the tobacco smoke exhaled by a smoker or group of smokers in a Lehigh Foundry in Easton, closed or open environment.

Pennsylvania. In case you don’t Ischemia: Tissue that is deprived of sufficient blood and oxygen. know what a foundry is, it’s the Catabolic process: The sequences of enzyme-catalyzed reactions by closest thing to hell on earth. I am which relatively large molecules in living cells are broken down, or dead serious about that. First of all, degraded. the place was extremely hot, dirty Metabolism: A chemical alteration of drugs by cellular processes. and dangerous, and those are the Metabolites: Chemical products in metabolism. good points. The first day I worked there, the foreman opened up this trap door in the floor and told me to go into this cellar and shovel sand onto the conveyer belt that was down there. When I got down there, I was up to my knees in black sand. It was so dark down there I couldn’t see two feet in front of my face.

There was sand swirling around all over the place. When the foreman called for me to come back up after about an hour in that hell hole, two other guys came up with me and I didn’t even know they were down there with me. I am serious, it was just that dark and dirty in that dungeon. At the foundry we made missiles. The black sand was used to make molds for the missiles. Once the molds were made, they were filled with molten steel and then set to cool. After the molds cooled off, they were put in this large contraption called a shakeout machine. When the machine was turned on, it would shake the sand off of

the molds. The missiles were then gathered and stacked. As you could probably imagine, the entire place was saturated with black sand. I’m not lying. I could go in the front door, walk through the entire building, which was about a block and a half long, and when I walked out the back door, I had so much sand on me that I’d be darker than Bill Cosby after a two week tropical vacation. You can probably comprehend what it would be like to pull an eight hour shift in that environment. After a day’s work, I would have sand in my hair, nose, ears, pants, shoes and even in my underwear. To give you an idea of how bad it was, when I went back to college at the end of the summer, I was still blowing sand out of my nose two weeks later!

From day one, I complained to my father that I was going to get black lung if I continued to work there. I even threatened that I was going to report him for child abuse. However, complaining to my father was like complaining to the Surgeon General…he always had an explanation as to why, in his words, “It will be all right!” I didn't want to admit it at the time, but his explanation for why I wouldn’t develop black lung was rather plausible…which would make me mad as hell.

The first thing he would point out is that small particles (like sand) that are inhaled are usually trapped by hairs and mucous in your nose. He also mentioned that even if particles evaded the nasal tract, specially constructed wind tunnels in the mouth and nasal passage would swirl the particles around until the saliva in my mouth snared them. Then, he said I could either spit the sand out or swallow it. If I swallowed it, the particles would go down my esophagus into my stomach and eventually to the Tidy Bowl Man. I’d say, “Yeah Dad, but with all of that sand in the foundry, some of it would have to get into my bronchial tube.” Naturally, my dad had an explanation for that too. He would say, “Even if some of the sand got that far, your bronchial tubes produce a sticky mucous that would trap the particles.” Then, I would counter, “Even if the mucous did trap the sand, wouldn’t gravity force the mucous and the particles into my lungs?” He would give me that stupid Italian smirk and say, “Yeah! Except your bronchial tubes are lined with hairs called cilia, which sweep the trapped particles back up into your mouth so that you can either spit it out or swallow it and send it to the Tidy Bowl Man.” Then, he’d say, “Even if the particles got by the cilia, you have a cough reflex near the base of your bronchial tube that when activated will force the particles back up the respiratory tract and into your mouth.”

Of course, I still wasn’t going to give in. Heck, I was fighting for my life. “With all that sand,” I would protest, “some of it has to get into my lungs.” As you might expect, my father had an answer for that too…he had a freaken answer for everything. Don’t you just hate people like that? He would assert, “If particles happened to get passed all these protective mechanisms…your wind tunnels, the bronchial cell mucus, the cilia (mucal-escalator) and the cough reflex…and get to your lungs, white blood cells will attack the foreign particles and destroy or immobilize them.” So, according to my dad, I had a whole arsenal of defense mechanisms to protect me against foreign particles entering my respiratory tract. When I checked his story out in my anatomy and physiology books, I realized that he was right…to a certain point. That really made me mad.

Normally, a person’s defense mechanisms would clean the lungs of any dangerous materials. Even in an environment like the foundry, the system is adept at keeping the respiratory tract fairly clean. However, when the system is constantly overloaded, it may not be able to remove all the

particles. Consequently, there is a danger of detrimental effects like black lung. That’s right. My father was trying to kill me. Of course, I am talking about an environment that is extremely polluted. In a normal environment, the defense mechanisms are extremely efficient at keeping the respiratory track as clean as a whistle.

So, what does all this have to do with smoking? Well, I am going to tell you right now.

Cigarettes ____________________________________________

Cigarette smoke is a heterogeneous aerosol composed of a mixture of hot air and gases that suspend small particles known as tar. Epidemiological studies have identified more than 4000 substances in cigarette smoke. Many of these substances contain carcinogenic (cancer causing) and mutogenic (produces mutation) substances. One of these substances is Benzopyrene, which is one of the most carcinogenic substances known to man.

CRITICAL POINT: The particle matter of cigarettes contains chemicals called phenols, which are thought to activate and accelerate dormant cancer cell growth in the body The particle matter of cigarettes also contains chemicals called phenols, which are thought to activate and accelerate dormant cancer cell growth in the body. In other words, you can have encapsulated or benign cancer and these chemicals can activate that cancer and cause it to metastasize throughout the body.

CRITICAL POINT: Cigarette smoking is so widespread and significant as a risk factor that the Surgeon General has called it "the leading preventable cause of disease and deaths in the United States.

Interestingly, the only two substances that people talk about are tar and nicotine. Although these two substances are extremely dangerous, there are two other chemicals in cigarettes that no one discusses, but they are every bit as dangerous as the tar and nicotine. They are nitrogen oxide and hydrogen cyanide. We know you never heard of them. Well, you are about to‌so get ready. Now, listen closely, this is really important. When you inhale nitrogen oxide, this gas immobilizes the cilia for a period of 40 to 60 minutes. In a word, the cilia become cataleptic‌they just lie there in a type of paralyzed state.

CRITICAL POINT: When you inhale nitrogen oxide, this gas immobilizes the cilia for a period of 40 to 60 minutes.

What happens once the cilia are knocked out? Any particle entering the bronchial tube is trapped by the mucous produced by the bronchial cells, but because the cilia are now ineffective in sweeping the particles upward, gravity will take over and force the mucous and particles towards the lungs. When this occurs, the accumulation of mucous in the lower part of the respiratory tract will trigger the cough reflex.

Although the cough reflex is fairly good at clearing particles to the throat, it is not 100 percent efficient. Thus, a lot of mucous and particles do in fact reach the lungs. We know what you are thinking, “What about the white blood cells? Aren’t they super efficient in eliminating foreign particles?”

You are exactly right, except for another small fact…that other chemical called hydrogen cyanide. Hydrogen cyanide does the same thing to the white blood cells that nitrogen oxide does to the cilia…it puts them into a lethargic state for a lengthy period of time. In a nutshell, these two gases render two of your defense mechanisms ineffective for an extended period of time.

CRITICAL POINT: When you inhale hydrogen cyanide, this gas immobilizes the white blood cells for a period of 40 to 60 minutes.

Let’s see what happens when that occurs.

Bronchitis ____________________________________________

This may surprise you, but tar is not a gas. Tar is simply soot or resin that is the byproduct of burning tobacco. Put in laymen’s terms, you get tar from burning tobacco. Tar is a sticky, gummy substance.

It’s the stuff that stains your teeth, your fingers, your clothes, your curtains or anything else with which it comes in contact.

CRITICAL POINT: Tar is not a gas it is simple shout resin.

As previously mentioned, foreign particles such as tar are normally not problematic because the air passageways are constantly being cleansed by the body's defense mechanisms. However, remember that the nitrogen oxide and the hydrogen cyanide immobilize the cilia and the white blood cells for a considerable period of time.

Consequently, the bronchial cells are unprotected against the irritating effects of cigarette tar. In essence, what happens is that when you inhale a cigarette, the tar starts collecting on the epithelial (lining) tissue of the bronchial cells. Then, the tar begins eating its way through the epithelial tissue, eventually causing inflammation of the tissue. The bronchial cells, in an effort to cool the inflammation, will produce more mucous than normal. Since the cilia cannot remove this excess mucous, gravity forces it downward into the bronchial tube. This accumulation of mucus and tar in the bronchial tube activates the cough reflex, which in turn produces a deep cough in an attempt to force the material back up into your mouth. I know I said that a few seconds ago, but now I am saying it for a different reason.

CRITICAL POINT: Bronchitis is an inflammation (or irritation) of the airways in the lungs. Airways are the tubes in your lungs that air passes through. They are also called bronchial tubes. When the airways are irritated, thick mucus forms in them. The mucus plugs up the airways and makes it hard for air to get into your lungs. Symptoms of bronchitis include a cough that produces mucus (sometimes called sputum), trouble breathing and a feeling of tightness in your chest.

If you haven’t figured it out yet, you’ve just developed a disease called bronchitis…the inflammation of the bronchial cells. And what is the major symptom of bronchitis? If you said a deep cough, you are perfectly right. Now you know why that is the case. Interestingly, people who work in extremely polluted environments (coal mine, foundry, etc.) can develop bronchitis. Nevertheless, the incidence of this disease in smokers is 20 times greater than in non-smokers. And that’s just the beginning of what smoking can do to you.

Cancer _____________________________________

If you are a regular smoker, (about a pack of cancer sticks a day) in roughly 20 years, the tar that coats the epithelial tissue of the bronchial cells will begin to eat through the lining of the cell. Once inside, the tar somehow (the etymology of this process is not known) rearranges the genetic structure of the cell, causing it to become an X or mutant cell. These mutant cells are a modification of the original cell, except that they don’t have a productive function. They compete for oxygen and nutrients and replicate, but do not perform any useful function.

They are basically parasitic in nature. They take from you, but give you nothing in return. Did you ever date someone like that…they take everything you have, your money, your car, your house and they gave you nothing in return? They are called players or gold diggers. What do you do with these people? I will tell you what you do with them. You cut them out of your life. The same thing you do with those X-cells.

CRITICAL POINT: Tar is a carcinogenic agent that can cause cancer.

Exposure to tar, singly or in combination with other agents, can initiate cancer under conditions not entirely understood.

In fact, as soon as your doctor detects that you have those X-cells, he will take you down to the operating room, put you on a marble slab, take out a Black'N'Decker chain saw and slice your chest cavity wide open. He will then pin your chest back so that he can get a better look. If there are just a few X-cells in there, what he’ll do is take out a set of those $19.95 Ginsu knifes…you know, the ones that come with that cute little purple table cloth…and cut them out. If, on the other hand, he gets in there and your chest is inundated with X-cells or if some of the X-cells have became metastatic and recolonized in different areas of your body, there is a good chance your doctor will just sew you back up.

He will tell you to go home and make out your will because you will be checking out in the near future.

Why? Because those little X-cells are cancer cells. That’s right! What you have is cancer, the second leading cause of death in middle aged American men and women.

CITICAL POINT: Quitting smoking substantially reduces the risk of developing and dying from cancer, and this benefit increases the longer a person remains smoke free. However, even after many years of not smoking, the risk of lung cancer in former smokers remains higher than in people who have never smoked.

Emphysema _______________________________________________

Oh, but wait! There’s more. If you’re unfortunate enough to survive the cancer, there’s a good chance that you’ll develop a disease that’s even worse…emphysema. Not only will this bad boy shorten your life, it will also make you wish you were dead while you are alive. The disease has a significant deleterious effect on the cardiorespiratory system. As a result, even the simplest tasks like walking across the room can be extremely taxing. Some emphysema patients can’t even blow out a match that’s only two inches from their lips.

When you develop emphysema, your entire life is compromised. You can’t run, you can’t swim, you can’t have sex, you can’t play ball…you really can’t do anything that requires any type of cardiovascular endurance. Did I mention you can’t have sex? Actually, you probably could do all

those things, but you just couldn’t do them for more than 30 seconds. Trust me on this one, your life is totally screwed when you develop this disease.

The alveoli are the tiny air sacs I talked about when I was discussing the vascular system. Remember, the alveoli are where the capillaries give off carbon dioxide and pick up oxygen. The gases are exchanged by creating a pressure differential. The basic principle underlying the movement of air or gas is that it will travel from a high pressure area to an area of lower pressure. It will also travel from an area of greater concentration to an area of lower concentration. The process is called diffusion and it takes place as a result of the pressure gradient or difference. The muscles and the elasticity of the alveoli create the pressure differential that first allows air to flow into the air sacs and allows air to be expelled from the sacs.

CRITICAL POINT: The basic principle underlying the movement of air or gas is that it will travel from a high pressure area to an area of lower pressure. It will also travel from an area of greater concentration to an area of lower concentration. The process is called diffusion and it takes place as a result of the pressure gradient or difference.

Let’s begin with inspiration or the act of taking air into the alveoli. We talked about all of this earlier, so this should basically be a review for you. First, the muscles around the air sacs contract, thereby expanding the alveoli cavity from side to side and from front to back. The enlargement of the alveoli cavity causes a decrease in pressure. Air pressure outside the alveoli is then greater than the air pressure inside, causing air to flow into the alveoli until alveoli pressure is equal to the outside pressure.

Remember the balloon analogy we used when talking about how air gets into the lungs. Well, it applies here too. What happens to a balloon when you put it under water? It shrinks because of the water’s pressure on the balloon. Does the amount of air in the balloon change? No. It’s still the same. So we have the same amount of air in a smaller space. So the pressure in the balloon goes up. Consequently, when you take the balloon out of the water, the size of the balloon expands and the pressure decreases according the change in the size of the balloon. The alveoli are like balloons so that as the space that holds the air expands, the pressure in them goes down and air rushes inside them.

Now, let’s see how air and/or gases get back out of the alveoli. Let’s look at expiration or the expelling of air from the alveoli. As previously mentioned, expiration is nearly the opposite of inspiration. In this case, the muscles relax, thereby returning to their original position. When this occurs, the volume of the alveoli cavity decreases by all parameters, causing the pressure inside the alveoli to increase. Therefore, the pressure in the alveoli is greater than the outside pressure, which causes air to flow out of the cavity until the external and internal pressures are once again the same. If you don’t understand what I am talking about, Simon says, “Read it again.” Or if you want the easy

way out, just put a gun to your head.

No! No! No! Simon didn’t say put a gun to your head, you big blockhead. Simon said, “Read it again.”

Okay, now that you understand how air enters and exits the alveoli, let’s see how tar gums up the whole works.

As mentioned, the capillaries intermingle with the millions of tiny air sacs throughout the lungs. It is there in the tiny air sacs that the real work of the vascular system takes place. The carbon dioxide in the capillaries is exchanged for the oxygen in the alveoli. The oxygen is necessary for breaking down ATP. Without oxygen, your cells can’t do any work. Yes, I talked about all of this before too. So you are getting a great review here.

Anyhow, what happens with emphysema is that the tar collects on the alveoli walls, decreasing their elasticity and their ability to create a pressure differential. Air is allowed into the alveoli through their normal expansion, but it is then trapped due to the blockage caused by the tar. As pressure builds, it causes the air sacs to rupture. This reduces the surface area in which oxygen and carbon dioxide can be exchanged. Without the air sacs, the blood cannot exchange its carbon dioxide for oxygen. Without oxygen being supplied by the blood, the cells can’t do work and you know what that means…NO SEX! In brief, emphysema compromises your aerobic capacity. As the condition worsens, you get less and less oxygen into the body. Eventually, you can’t even get enough oxygen to survive. The long-range consequence is a slow and painful suffocation. Isn’t that great news?

CRITICAL POINT: Oxygen is necessary for breaking down ATP. Without oxygen your cells can’t do any work.

I had a wonderful experience when I was a little boy. My big sister who was a private nurse took me to meet one of her patients. The guy she wanted me to meet was suffering from emphysema. He was in bed and he had this oxygen tent wrapped all around him. After my sister introduced us, the guy started giving this magnificent lecture about why I should never smoke. Basically, he told me that if I smoked I would end up like him. To be honest with you, I really wasn’t paying much attention to what he was saying. I acted like I was interested, but I really could have cared less what he was talking about. Then, all of a sudden, the guy started choking. At first, I thought he was just playing, but he started coughing up fluid…I thought it was blood. Naturally, I called for my sister. By this time, the guy ∞ DRUGS in Perspective ∞ __________________________________________________________________ was yelling, “I can’t breathe, I can’t breathe.” When my sister got there, she Why Is It So Tough To Stop Smoking? told me to go outside. I stood right outside the door listening. The guy started yelling, The basic premise of behavior modification is that behavior is a “I don’t want to die, I don’t want to die.” I function of its consequences. This is one reason why smoking is a stood there for a good 30 minutes listening hard behavior to deal with. When you smoke, you get immediate positive reinforcement; therefore you want to repeat the behavior. The to that guy begging for his life. It took him problem is that you don't receive the punishment until 20 or 30 years that long to die. It was like someone had a down the road when the myriad of health problems surface. The pillow over his head and right when he greatest difficulty in achieving self-control involves the conflict was ready to pass out; they took it back off between long term and short term consequences of behavior. so he could get a little air. After he had a

little air, they put the pillow back over his head. That is what it reminded me of…a slow, painful and suffocating death. Being in that oxygen tent, the guy had all the oxygen in the world, but he couldn’t process it because his alveoli were totally destroyed. I wish you had been there with me because if you had, you would never consider lighting up a cigarette for the rest of your life. Like I said, it was a great lesson for me.

That’s just some of the things that tar in the cigarette smoke will do to you. In reality, all that is just kid stuff…the real “ass kicker” is nicotine. The majority of deaths among smokers are mainly due to the effects that nicotine has upon the cardiorespiratory and circulatory systems. Coronary artery disease alone accounts for about 45 percent of the deaths related to smoking. If you add up all the other cardiorespiratory diseases that are linked to nicotine, they would account for over 50 percent of all smoking-related deaths. If you want to know physiologically how all of that works, raise your hand…too bad, I am going to tell you anyway.

Nicotine ____________________________________________

Nicotine is a central nervous system (CNS) stimulant. It affects the body in much the same manner as a mild amphetamine. Its action on the body causes the heart rate to increase the peripheral blood vessels to vasoconstrict, and adipose (fat) stores to release fatty acids into the vascular system. It also gives you a feeling of mild euphoria or well-being. That is one reason cigarettes are so popular…they make you feel good when you use them.

Generally, when a response is followed by an unpleasurable consequence, the response will decrease.

Conversely, when the response is followed by a pleasurable consequence, the response is increased. As mentioned, the response of smoking is generally followed by a pleasurable consequence (mood elevation). Thus, the frequency of the behavior (smoking) is likely to increase, which eventually leads to psychological addiction. This form of habituation or mental dependence is nothing to sneeze at. Research has consistently shown that habituation is much more difficult to overcome than physical addiction to drugs.

CRITICAL POINT: Nicotine is a central nervous system (CNS) stimulant. Its action on the body causes the heart rate to increase the peripheral blood vessels to vaso-constrict and adipose (fat) stores to release fatty acids into the vascular system. It also gives you a feeling of mild euphoria or well being.

The physical withdrawal from even the harshest of drugs would only take six to ten days. Once accomplished, the body’s craving for the drug is gone forever. However, once you develop habituation for a drug, you have to contend with that persistent craving throughout your life. Remember how much trouble Lori had with her psychological craving for heroin. Of course, physical addiction is no bowl of cherries either. The physical addiction to a drug has forced even the strongest of wills to crack.

Unfortunately, cigarettes are extremely addicting.

CRITICAL POINT: Nicotine is physically and mentally addictive. According to contemporary research, nicotine is more physically addictive than heroin.

According to contemporary research, nicotine is more physically addictive than heroin. Actually, it has been shown that the success rate of physically withdrawing from heroin is significantly higher than that for nicotine.