This is an essay I wrote about the effects of smoking on the body for my Anatomy and Physiology class. It’s 6 pages when double spaced and stuff. If you actually spend the time to read it, please comment. Thanks!

Smoking and it’s effects on the body

I chose to report on smoking for this class, because I recently quit smoking a little over 2 months ago. I figured that if I could get a good picture of what was happening in my body, it would help me to stay quit. It is a dangerous and deadly habit. Tobacco and nicotine related diseases kill more than 440,000 people every year. “That’s like 2 jumbo jets crashing and everybody being killed every day.”

Tobacco has been tied to humanity for millennia. It was (and still is to some extent) used in religious ceremonies of some Native Americans, partly because of it’s hallucinatory effects. Controversy as to the effects on the human body began as early as the 16th century soon after it was introduced to Europe by explorers returning from the New World. It was praised for pleasurable and medicinal purposes, but at the same time it was condemned as a foul-smelling, loathsome custom, and thought to be harmful to the brain and lungs.

Now we have Science, and we know empirically that smoking cigarettes has much more devastating effects on the human body than curative ones. The 50s were a time of worldwide public declarations of the harmful effects of smoking, especially with respect to lung cancer and cardiovascular disease, followed by denial and suppression of these risks from the tobacco companies. In 1957, the US Surgeon General declared “The Public Health Service feels the weight of evidence is increasingly pointing in one direction: that excessive smoking is one of the causative factors in lung cancer.2” The United States also did extensive research which led to the release of the Surgeon General’s report on Smoking and Health in 1964. It was a watershed event. It revealed to the public once and for all the danger of smoking cigarettes. It used sound scientific investigation based on animal testing, clinical and pathological observations of humans, and statistical studies that followed the lives of smokers.

That study and subsequent studies since that time have revealed that there is a compound of factors that contribute to the health risks brought on by smoking. One is the the way nicotine reacts in the body, and another is from the effects of tar. But there are 4000 different chemicals including 200 that are known to be toxic to the human organism. First, the effects of nicotine.

Nicotine can act as a stimulant or a tranquilizer, depending on the circumstances and amount consumed. Nicotine is a poison produced in the tobacco plant thought to be useful to the plant as a self defense mechanism to ward off insects. It enters into our organism through a cigarette during the inspiration stage of pulmonary ventilation (a fancy term for ‘breathing in’). Most of it stays in our lungs, but the rest goes into our blood stream, reaching our brain in about 10 seconds and the rest of the body in about 20.

The stimulating initial “kick” of the cigarette an Adrenaline Rush caused by the nicotine stimulating the adrenal medulla to release epinephrine (adrenaline) into the blood. In general, epinephrine (along with norepinephrine) have the same effects on target organs as if they were directly stimulated by sympathetic nerves. This makes the adrenal medulla a fascinating organ. Technically, is is part of the endocrine system, but it acts as part of the nervous system. Instead of firing a synapse, it releases secretions into the blood. It’s like it’s supposed to be a ganglion of nerves, but it sends it’s messages through hormones instead of an axon, so it’s an endocrine organ. In this sense, nicotine can be seen as effecting the sympathetic nervous system by over-stimulating this natural reaction.

Nicotine also crosses the blood-brain barrier and gets into the central nervous system. This is the key to it’s tranquilizing effects. It binds to special receptors (nicotinic acetylcholine receptors or nAChRs) that we have in the plasma membrane of some of our neurons. This binding stimulates the neurons to fire and gives us the relaxed and tranquil feeling that comes from smoking. In high doses, this can even be psychotropic (which is why it finds it’s use in some religious ceremonies).

Though these may seem like good things, too much of a good thing desensitizes us so that we want more. This is the probable reason that nicotine is one of, it not the most addictive substance known to man.

But the most deadly thing about nicotine relates back to how it stimulates epinephrine production. Epinephrine secretion is part of the system that kicks your body into a fight or flight response. It targets receptors that cause an increase in the rate and force of contraction of the heart muscle, narrowing of the arteries, and stimulation of lipolysis in fat cells (or fat breakdown). These things lead to a really bad thing: heart attacks. Epinephrine also stimulates other fight-or-flight responses like the dilatation of bronchioles, increase of oxygen consumption and heat production throughout the body, the dilatation of the pupils and the inhibiting of some non-essential processes. But lets look at the first three key physiological responses to increase epinephrine levels that lead to heart attacks.

At first glance, the increased activity in the heart muscles may seem beneficial. It forces the heart to to pump against increased resistance making it work harder which works out the the thick muscle part of the heart, causing it to enlarge. But this is bad. Unlike skeletal muscle that grows stronger when it gets bigger, when cardiovascular muscle enlarges, it gets thinner and weakens.

Secondly, it stimulates (temporarily) the narrowing of arteries. This makes it harder for blood to to flow which increases the pressure (but it flows faster to get more oxygen out there, which is why it’s a good thing in a fight-or-flight response).

Lastly, it stimulates the breakdown of fat. This seems like a good thing. Who doesn’t want to get rid of fat and loose weight? The breakdown of fat can also be a positive thing because fatty acids are released and become available to be converted into ATP for energy. The problem is where that fat can go: into your blood stream. We have all heard that high cholesterol in your blood is bad. That is essentially what happens. The fat can build up as plaque in your arteries making it harder for blood to flow.

These factors create higher pressure in your blood. Over prolonged periods of time, this is a pathological disease known as hypertension. Hypertension is really bad – it can kill you. There is a direct correlation between hypertension and strokes, heat attacks, heart failure, aneurysms and renal failure. Just for fun, let’s go into each of these and how they are a homeostatic imbalance (cause of disease) in the organism (you).

A stroke is when you temporarily loose the function of parts of your brain due to loss of blood flowing to it. This can cause permanent brain damage. Though highly unlikely to turn you into a zombie, you can potentially loose control of functions of your body and/or die.

A heart attack is also known acute myocardial infarction. A part of your heart (namely the myocardium, made up of cardiovascular muscle) dies (infarcts). Acute just means that it is short, sudden and intense. This is a very serious and deadly thing. A dead heart is as bad or worse as brain dead. Heart failure can occur, which means your heart just lost part of it’s function and cardiac output is insufficient for the body’s needs.

An aneurysm is a blood-filled dilation of a blood vessel. It fills up like a balloon. Usually at the base of the brain or the aorta. If that balloon pops – bad news. Towards the good end of that spectrum of nastiness is a hemorrhage, on the bad side of that equation is sudden death.

Renal (or kidney) failure means your kidneys don’t work properly. This is deadly as well. Your kidney is such an important part of the body, that if it were gone, you’d die in seconds. The kidney does so many things that I’m not going to get into for lack of space in this essay.

So that’s how nicotine kills. The other main killer in cigarettes is tar. Not tar like we use in roads, but rather the partially combusted particles, or soot, produced by the burning of tobacco. It coats your teeth, taste buds, throat, lungs and the whole respiratory system. As it coats your taste buds, it makes it harder to taste food. More seriously though, is what it does lower down in the trachea. It overwhelms the natural role of mucus and cilia as a defense against toxins coming in to your system. Continuous irritation prompts the production of more mucus, but smoking also slows the movement of cilia to move the mucus along. So you get more mucus, and less ability to move it along. In a chronic state, this is a condition known as emphysema. The way someone dies from emphysema is that their lungs fill with mucus and they essentially drown in their own spit There is also bronchitis deadly but less severe, which is the inflammation of the brachial tubes leading into the lungs.

This still does not take into account all the other toxins in cigarette smoke. A really dangerous thing that smoking does is increase the likelihood of cancer in your body. Cancer is as much as 20 times more likely to occur in people who smoke. Along with heart attacks, cancer is the main cause of death, period. The most dangerous is lung cancer, but smoking can also stimulate cancer in the larynx, esophagus, urinary bladder, and lips (especially with pipe and cigar smokers).

Cancer (malignant neoplasm) is an interesting phenomena that we still don’t completely understand. A whole other essay could be written about it and whole fields of study are devoted to it, but I will try to nutshell in a few paragraphs.

Basically, it is a loss of control of mitosis (the reproduction of cells). It is marked by 3 properties: it displays uncontrolled growth, invasion and metastasis.

There is a process called programmed death of a cell in which it naturally dies on it’s own accord. In a cancer, this process is stopped and the tissue grows out of control. It also invades the surrounding tissue rather than pushing it aside. In some cases it metastasizes, or hitches a ride in the blood stream to invade other parts of the body. A tumor is very similar, except it is self-limited and does not invade or metastasize.

Lung cancer is especially of concern because it is responsible for one third of all cancer related deaths. One of the reason why lung cancer is so deadly is because it can metastasize to other organs in the body very quickly.

So smoking is the major cause of emphysema, cancer and heart attacks. Cancer and heart attacks are the main cause of human death. The key thing about smoking is that even though it is very tough to quit, it is one of the preventable causes of death that we know about.