Popular Science Monthly/Volume 2/December 1872/The Physiological Position of Tobacco
|THE PHYSIOLOGICAL POSITION OF TOBACCO.|
IN speaking of the physiological position of tobacco, we have to deal with the action of the essential principles of that plant upon the human system. The peculiar effects of tobacco are due to the action of the essential oil of tobacco in the case of chewing and snuffing, and to that combined with the empyreumatic oil in smoking. Nicotine, as this essential principle is called, is so deadly an alkaloid, that the amount of it contained in one cigar, if extracted and administered in a pure state, would suffice to kill two men. According to the experiments of Vohl and Eulenberg, the nicotine is decomposed, in the process of smoking, into pyridine, picoline, and other poisonous alkaloids, which can also be obtained in varying quantities by the destructive distillation of other vegetable substances.
Nicotine, as for convenience we may continue to call the poisonous principles of tobacco, can enter the body through various channels by the stomach, by the lungs, by subcutaneous injection, and by the skin itself. But, in whatever manner it enters the human system, its effects are, in the main, uniform.
The most immediately noticeable symptom following smoking is the undue acceleration of the laboring forces of the heart. Under the stimulus of tobacco the heart beats more quickly, as is evidenced by the rising pulse. We have not the mass of detailed evidence as to this fact which exists in relation to alcohol, but the experiments made by Dr. Edward Smith, and related to the British Association in 1864, are full of interest. "The experiments were made at 10 p. m., when the rate of pulsation naturally declines (as he had proved by hourly experiments published in his work on the 'Cyclical Changes of the Human System'), and at least four hours after any fluid or solid food had been taken. They were made in the sitting posture, after it had been maintained fifteen minutes, and with the most absolute quietude of body and mind; and thus all influences were eliminated but those due to the tobacco. The rate of the pulsation was taken every minute for a period beginning two or three minutes before the smoking began, and continuing during twenty minutes, or until the pipe was exhausted.
The following are the chief results obtained:
Pulsation before smoking was 74½ per minute.
Smoking 6 minutes—79, 77, 80, 78, 78, 77 per minute78.1 average.
Smoking 7 minutes—83, 87, 88, 94, 98, 102, 102 per minute93.4 average.
Smoking 8 minutes—105, 105, 104, 105, 105, 107, 107, 110 per minute106 average.
After smoking 11 minutes—112, 103, 107, 101, 101, 100, 100, 100, 100, 98, and 91.
There was thus a maximum increase of 37½ pulsations per minute.
(Smoking through camphor julep in a hookah.)
Pulsation before smoking, 79½ per minute.
Smoking 6 minutes—81, 81, 81, 83, 82, 82 per minute81.6 average.
Smoking 17 minutes—85, 89, 89, 93, 96, 90, 94, 94, 93, 92, 95, 95, 95 96, 94, 97, 9393.
The maximum increase was 17½ pulsations per minute.
(Smoking an empty pipe.)
Pulsation before smoking, 78 pulsations per minute.
Smoking 11 minutes—76, 78, 77, 76, 79, 79, 80, 80, 79, 78, and 79.
There was no increase in the rate of pulsations from the effort of smoking, or from its interference with the respiration.
(To ascertain if, after smoking 6 minutes, during which the effect is very small, and then ceasing smoking, any increase in the effect would follow.)
Pulsation before smoking, 75 pulsations per minute.
Smoking 6 minutes—76, 75, 79, 79, 76, 78.
Smoking 1 minute—82. Cease smoking.
Smoking 10 minutes—81, 88, 83, 82, 84, 83, 83, 80, 82.
The rate of pulsations was maintained, but was not materially increased.
(To prove if the rapidity of smoking causes a variation in increase of pulsation.)
a. Greater volume of smoke.
Pulsation before smoking, 70½ per minute.
Smoking 6 minutes—68, 70, 71, 70, 72, 7470.8 average.
Smoking 6 minutes—76, 77, 86, 89, 91, 9485.5 average.
Smoking 4 minutes—98, 05, 96, 9596.0 average.
The maximum effect was thus 27½ pulsations per minute.
b. Smoking faster.
Pulsation of the last minute in the previous part of this experiment, viz., 95 per minute—smoking 3 minutes, 94, 49, 96.
c. The pipe recharged.
Smoking 5 minutes—87, 93, 96, 96, 96.
There was, therefore, a large effect upon the pulsation, but probably not more than would have occurred with ordinary smoking.
Numerous other experiments were made with tobaccos of different reputed strengths and upon different persons, and the author gave minute directions as to the proper method of making such inquiries."
The heart, then, during the act of smoking, was doing extra work; in some of the experiments this additional labor amounting to more than 50 per cent.
The effect upon the heart is not caused by direct action upon that organ, but by paralyzing the minute vessels which form the batteries of the nervous system. Thus paralyzed, they can no longer offer effectual resistance, and the heart, freed from their control, increases the rapidity of its strokes, expanding the vessels, with an apparent accession, but real waste of force.
Its effect in lowering the animal temperature is very striking. When the walls of the blood-vessels are distended with that fluid, the increase in volume decreases the rapidity of the circulation and augments the local warmth. When the walls partially collapse, the circulation becomes quicker, but the heat diminishes. The heat, in fact, is transformed into motion.
The action of nicotine upon the iris is well known, yet, while some consider it to produce dilatation, others affirm its effect to be contraction. The iris is composed of two orders of muscular tissue. The circular fibres influenced by the motor oculi, and the radiating fibres obeying the great sympathetic, perform the two functions of the iris, dilatation and contraction. The stimulation of the third pair of nerves causes a contraction of the pupil; a larger dose of nicotine destroys its susceptibility and dilatation follows, the upper lid falls, strabismus ensues, the eyeball becomes fixed—in short, the motor power of the eye is paralyzed. M. Blatin considers that the muscular fibre of the eye is not at all affected by the poison.
Blatin proposes to divide tobacco-poisoning into two classes, acute and chronic. The first is the result of a large or unaccustomed dose; the second, the accumulative consequences of doses, perhaps small, but continually repeated.
The unpleasant experiences of the first pipe will enable most smokers to understand the nature of this acute poisoning. Children have even been made ill by sucking at pipes, empty, but already coated with tobacco-juice. Sometimes a very slight dose exercises a fatal effect upon systems in which tolerance has not been established. Thus a youth of fourteen, having smoked fifteen cents' worth of tobacco as a remedy for toothache, fell down senseless and died the same evening. Blatin also tells us of a medical student, aged twenty-two, who, after smoking a single pipe, fell into a frightful state—the heart became nearly motionless, the chest constricted, his breathing was extremely painful, the limbs contracted, the pupils insensible to light, one dilated, the other contracted. These symptoms gradually lessened, but did not disappear until four days after.
But it is chronic nicotism which has the greatest interest for us. The poisonous effects of tobacco in larger doses are too evident for denial, and need scarcely be insisted upon. Far more important is it to learn whether tobacco, in the quantities daily consumed by its habitual users, has a permanently injurious effect upon the human system.
It is often only after a number of years that nicotic symptoms appear, as though the poison acted by a process of accumulation, until the system was charged to satiety. And thus any thing which disturbs the equilibrium of the functions, and so diminishes the elimination of the poison, may give rise to morbid phenomena.
There is a theory not unknown, even among medical men, that the toxic influences of tobacco are only transitory, and that all the poison is ultimately expelled from the system. But it is certain, from an experiment of M. Morin, that the nicotine can be detected in the tissues of the lungs and liver after death.
M. Blatin regards the various local affections as trifling, when compared with the gradual saturation of the system with nicotine, which, accumulating in the tissues, waits for the opportunity, varying, according to individual habits and constitution, of declaring its poisonous nature.
The trembling, which is one of the usual symptoms of acute, is also a common result of chronic, nicotism. A very distinguished Parisian physician had hands which shook so much that he could not write. Whenever he remained without tobacco for any length of time, these tremblings disappeared. Another case mentioned by Blatin is noteworthy. A man of forty-five years consulted him respecting violent and numerous attacks of vertigo. When he felt one of them approaching, he was obliged to lie down wherever he might be, in order to avoid falling. In the country, where he had plenty of exercise, they were less frequent than in the town, where his occupation was sedentary. Cessation from tobacco and a tonic regimen quickly restored him.
A physician of fifty-two was afflicted with similar disagreeable symptom's, and was also cured by abstinence. Habit had become so strong that he could not resist at times the temptation to slight indulgence. Finding that these returns to tobacco were immediately followed by his old painful attacks, he renounced it forever.
The circulatory system presents in chronic nicotism similar symptoms to those found in acute poisoning. The most noticeable of these is the intermittent pulse, of which many cases have been collected by Decaisne and others.
Decaisne speaks of narcotism of the heart, but Blatin does not consider the action to be directly upon that organ, but considers the effects described to result from an irregular relaxation of the ganglia of the great sympathetic nerve.
When a person suffering from intermittent pulse was carefully examined, Blatin found the stoppage in the heart's beat followed a series of apparently normal movements. The systole and diastole succeeded in due regularity, and nothing in the play of the central organ indicated trouble, when the heart suddenly stopped in diastole, sometimes for the space of three arterial pulsations. When it awakens from this syncope its action is abnormally quick, as if it wished to make up for the lost time, and force the mass of blood across the organs at one stroke. But, with force insufficient for this purpose, it is exhausted in fruitless efforts, hesitates, wavers, acquires fresh power, commences again, now violent, now feeble, and fulfills very imperfectly the duties which it should perform. Gradually it calms; a foreign element seems to appease the tumult, the heart again becomes regular. The explanation appears to be that the irritation of the sympathetic nerve stops short the movements of the heart, and thus causes the intermittence; then the susceptibility of the nerve is lessened or paralyzed, and the cardiac functions are left to the sole direction of the auto-motor ganglia; hence the disordered beats, which decrease as the nervous force coming afresh from the pneumogastric moderates and regularizes it.
From intermittent pulse to angina pectoris the distance is not far. That tobacco may produce all the usual symptoms of that painful disease has been abundantly shown by Beau. To the cases which he has cited may be added an epidemic of this nature noted by M. Gelineau, with which a great part of the crew of the Embuscade were struck. The patients were all great smokers. It is worthy of notice that this disease is much more common among men than women.
Difficulty of breathing approaching asthma has also been recorded. Blatin gives a case of a young officer whose asthma could be attributed to no other cause, and who was cured by a simple abstinence and tonic medicines.
Tobacco, acting upon the cardiac and pulmonary branches of the pneumogastric, is not likely to leave untouched its gastric terminations. In an animal under the influence of small doses of nicotine the gastric juice is secreted with increased rapidity, and the action of the walls of the stomach is more noticeable. With strong doses or long-continued usage this secretion is very considerably diminished, and the peristaltic motion enfeebled. That is to say, the tobacco acts upon the pneumogastric, excites it in small, and paralyzes it in large, doses. The smoker takes his after-dinner pipe or cigar to aid digestion. Undoubtedly, it excites the par vagum, increases the gastric secretion, and accelerates the peristaltic motion. Undoubtedly, also, this daily stimulation enfeebles the nerve, and digestion becomes more difficult. The swing back from the excitement causes a reaction, which only an increase in the doses can overcome. The nerve is partially paralyzed. The appetite fails, nutrition is impeded, dyspepsia reigns conqueror.
A military man of thirty-seven years fell into a consumption without any other affection antecedent or concomitant than distaste for food, and salivation. Dr. Roques, after various essays, learned that he was a great user of tobacco, which had led to a sort of chronic fluxion of the salivary glands, and an almost total cessation of the digestive functions, and consequently caused the feeble and consumptive state into which he had fallen. Gradual diminution and ultimate abandonment of tobacco led to a cure in about three months.
The influence of tobacco upon vision is well known. One of the symptoms produced in acute nicotism is blindness, and chronic nicotism gives rise to similar affections. Thus Mackenzie found that patients afflicted with amaurosis were mostly lovers of tobacco in some form. Sichel found cases of complete amaurosis, which, incurable by other means, were easily conquered by cessation from the weed. Hutchinson found, out of thirty-seven patients, twenty-three were inveterate smokers. The observations of Wordsworth and others have so clearly established the fact that the continued excitement of the optic nerve by tobacco sometimes produces amaurosis, that it is now generally cited in text-books as one of the causes of that disease.
We have completed our brief examination of the physiological action of tobacco, but in concluding it may be well to point to some portions of the evidence which are especially noteworthy.
The fact that tobacco reduces the animal temperature is an important one. It shows the fallacy of those who smoke to keep the cold out, and proves conclusively that tobacco is neither a generator nor conserver of vital heat, but, on the contrary, a wasteful destroyer of it.
The influence of tobacco, in liberating the heart from those restraints which regulate its healthy action, naturally leads to the conclusion that in frequent doses that organ must, sooner or later, undergo a structural transformation. Although when thus excited it has less pressure to overcome than when in a normal condition, yet the extra exertion cannot but be evil in its results, since it causes an irregularity in the supply of blood, and thus degrades tissue.
Tobacco belongs to the class of narcotic and exciting substances, and has no food-value. Stimulation means abstracted, not added, force. It involves the narcotic paralysis of a portion of the functions, the activity of which is essential to healthy life.
It will be said that tobacco soothes and cheers the weary toiler, and solaces the overworked brain. Such may be its momentary effects, but the sequelæ cannot be ignored. All such expedients are fallacious. When a certain amount of brain-work or hand-work has been performed, Nature must have space in which to recuperate, and all devices for escaping from this necessity will fail. It is bad policy to set the house on fire to warm our hands by the blaze. Let it, then, be clearly understood that the temporary excitement produced by tobacco is gained by the destruction of vital force, and that it contains absolutely nothing which can be of use to the tissues of the body.
Tobacco adds no potential strength to the human frame. It may spur a weary brain or feeble arm to undue exertion for a short time, but its work is destructive, not constructive. It cannot add one molecule to the plasm out of which our bodies are daily built up. On the contrary, it exerts upon it a most deleterious influence. It does not supply, but diminishes, vital force.
It has been denied that tobacco leads to organic disease, but the evidence is very strong the other way, and it would be very remarkable if continued functional derangement did not ultimately lead to chronic derangement of the organs; that it causes functional disturbance no one dreams of denying; indeed, it has been remarked that no habitual smoker can be truly said to have a day's perfect health.—Abstract from the Quarterly Journal of Science.