Thursday, August 4, 2011

PHYSICAL TRAINING SIMPLIFIED - The Complete Science of Muscular Development - (circa 1930) - CHAPTER 8 - CIRCULATION: THE FUNCTION OF THE BLOOD CIRCULATION AND ITS IMPORTANCE TO PHYSICAL CULTURISTS - By Mark H. Berry

We have been discussing the function of circulation as related to respiration and the proper nutrition of the muscles; therefore, we might profit by paying a little direct attention to the circulation of the blood and the organs which control it. The blood is contained in a closed set of branched tubes, which it completely fills, and which are commonly referred to as blood vessels; the blood is carried away from the heart through the arteries and distributed to all parts of the body. The veins carry the blood back to the heart from all parts of the body. The capillaries connect the arteries and veins throughout the body, and it is really in the capillaries that the work of the bloodstream is carried on. These small vessels are hair-like and form a network. A certain amount of force of pressure is necessary to carry the blood through the vessels. This force or pressure originates in the heart, but something else must be accounted for when explaining the complete working of the force or pressure.

The pressure thus exerted is known as blood pressure. The arterial blood pressure is much stronger than the pressure in the veins, known as venous pressure. The arterial pressure is fluctuating, varying from the strongest pressure in the larger arteries in a slightly weaker pressure in the small arteries. The venous pressure on the other hand, is strongest in the smaller veins, as the flow of blood is from the small veins to the larger veins; the venous pressure is low and relatively even. The rapidity of the blood flow is governed by the needs of the body.

Under ordinary circumstances, the general circulation is not affected. The blood supply to one organ or muscles, or to several organs or muscles may be increased without need of a greater flow throughout the entire system. The blood vessels in one part of the body may contract to counterbalance a dilation in another part of the body. However, when the increased demand is general throughout the system, then owing to the limited quantity of blood in the body, the rate of circulation must be increased to furnish the necessary addition. During minor exertions, the blood pressure is balanced, but this comparison cannot take care of all emergencies; therefore, a greater flow of blood means a greater blood pressure.

The arterial pulse is caused essentially by the variations of pressure within the artery, produced by the intermittent expulsion of blood from the heart; the systolic pressure is the highest point on this wave of arterial pressure; diastolic pressure the lowest point; the difference between the two, is called the pulse pressure. By certain indirect methods, it is possible to determine these pressures with a fair degree of accuracy. The factors effecting the difference between the systolic and diastolic pressures are: an increase in the amount of blood delivered at each beat from the heart into the aorta would tend to increase the difference; likewise a rapid emptying of the blood vessels would tend to increase this difference, whether or not the extra blood flowed through the capillaries into the veins, or regurgitated into the heart owing to a diseased condition of the heart.

The amount of blood pumped into the arteries and the amount which escapes from them in both directions must be equal, otherwise large amounts of blood would accumulate in, or disappear from the arteries. The rigidity of the arterial walls also exerts an influence on the arterial pressure. Were the arteries absolutely rigid tubes, the heart would be compelled to move the whole column of blood with each beat, while between the beats the flow of blood would stop. A high systolic pressure in the arteries and practically no diastolic pressure would then result; while the pulse pressure would be exceedingly high.

Arteriosclerosis sufferers frequently show high pulse pressures. As described above, slightest changes in the rigidity of the arteries will affect the pulse pressure, though to a less marked degree. The ventricles force a certain amount of blood into already full arteries; due to their flexibility, the arteries extend to accommodate this extra quantity; as long as the heart is contracting, the arteries extend, but as soon as the heart contraction is over the contractile powers of the arteries cause them to send blood into the capillaries rapidly enough to be at their normal size for the next heart contraction.

Arteriosclerosis is a condition wherein the arteries become stiff and rigid, and less adapted for the unceasing work they are called upon to perform; this condition is the result of either advancing age or disease. One suffering this condition runs a big chance by engaging in violent physical exertion; death is often brought about during times of great excitement or unaccustomed exertion, by the rupture of a tiny blood vessel in the brain. This is known as apoplexy, and is brought about by the blood vessels being incapable of handling the increased pressure; being stiff and hardened throughout the system, something has to give, so a small and weak part of the vascular system breaks to permit the necessary expansion. The arteries of the normal person being elastic, take care of the increased pressure demands by expansion, as we have explained.

Arterial pressure increases with age, as the arteries are less elastic. Likewise conditions of health may effect the normal muscular tone of the arteries and heart, if the heart loses its force or the arteries become too flabby the blood pressure is low, while the blood pressure is high, if the arteries are hardened or the heart over-stimulated.

The work of the heart may be made more difficult by increased peripheral existence, that is, greater contraction or constriction of the smaller arteries, necessitating increased work to send the blood circulating throughout the body. A wonderful power of adapting itself to the amount of work required of it, whether we are at rest, or exerting ourselves to the maximum, is possessed by the heart, which has been called the best motor know to man. Without hesitation or experiment, this organ instantly adapts itself to any demands made upon it. As soon as there is a demand the heart accomplishes it, though its capabilities are greatly increased by training; by reason of becoming accustomed to much exertion the muscular tissue on the heart is thickened giving it greater power to work, and making a rapid beat more easily sustained.

The factors controlling the blood pressure in the larger arteries are two in number-- the amount of blood pumped into the arterial system by the heart, and the resistance offered to the escape of blood from the system through the smaller arteries and capillaries. The elasticity of the vessels walls and the total quantity of blood in the body are of minor importance. These various factors may interact upon one another in a most complicated manner. Should the arterial pressure be increased from any cause, the vagus nerve is stimulated, with the result that the heart is slowed and less blood is delivered into the aorta; the volume of blood is rapidly changed, the blood vessels change their caliber, so that within certain limits the blood pressure is not altered.

Someone with a mechanical and mathematical turn of mind has figured it out that the arteries in the human body have strength enough to withstand the steam from a locomotive boiler, having a pressure of fifteen times the normal atmospheric pressure. Also that a barrel of blood passes through the vascular system in one hour; and in one day, two railroad tank cars could be filled with the amount of blood passing through the vascular system. The heart is indeed a wonderful pump. The heart of a man weighs, on the average, approximately ten to twelve ounces and contains four distinct cavities. The two upper cavities are known as the right and left auricle, and the lower two as the right and left ventricle, the latter being the most capacious by about 30%. The blood passes from the venae cavae into the right auricle and from there into the right ventricle. The blood then passes into the lungs and back into the heart through the left auricle, to the left ventricle, and out into the general circulation by way of the arteries, then through the capillaries, thence on through the veins and back again to the heart. It has been estimated authoritatively that little more than two ounces of blood is contained in the separate cavities at any one time, although the actual capacity of each of the cavities is at least twice as great. The complete process of circulation takes a little over one half of a minute.

The heart is approximately the size of your clenched fist, yet it carries on a tremendous amount of work. The entire volume of blood in the body passes through the heart once in about every half minute, an amount of something less than four grams in the average man. It has been established on reliable authority that the blood volume of man amount to, on the average, around 4.9%, or approximately one twentieth of the bodyweight. The heart beats well over one hundred thousand times daily or something like fifty million times in the course of a year.

Generally, the supposition is that the heart works continuously without interruption, still although true that the heart muscles receive no considerable rest, the heart cycle works in such a way that the various muscles involved each in turn pause for a short time. First both auricles contract, then both ventricles contract, following which there is a pause. The same order taking place again. This complete order is know as the cardiac cycle or heart beat. The average complete heart beat lasts 8/10 of a second, and is divided in this manner: the contraction of the auricles lasts 1/10 of a second, the contraction of the ventricle 3/10 of a second, the remaining 4/10 of a second being taken up the pause or rest. Each heart muscle contraction, both auricular and ventricular is known as the systole, while the period of relaxation is known as the diastole, either auricular or ventricular. The heart beat frequently varies, due to certain conditions, posture, sex, age, state of health and exertion. The heart beat is more rapid in females. The average normal male, sitting at ease, has a heart beat of 72; in females it varies to 8 or 10 beats more. Infants have a heart beat of well over 100. A material increase in the heart beat will be noticed as the result of exercise and digestion, or a fall in blood pressure; a rise in blood pressure will cause a diminishing of the beat.

The blood has several functions; removing carbon dioxide from the cells and carrying oxygen from the lungs to the cells; removing waste material from the cells, it also carries nutritive properties from the digestive organs to the cells; distributes internal secretions to various parts of the body; equalizing the chemical properties of the body. If the blood becomes heated in one part of the body it is cooled in another, thus the blood maintains an average body temperature. Furthermore, the blood is able to resist to a certain extent, due to the nature of its composition, bacteria and germs that might enter the body.

Certain chemical changes are associated with the activities of the living cells throughout the body; and interchange of food and waste material constantly taking place. Metabolism is the term by which the process of replacing worn out tissues with new material is known; while the process of assimilating food is know by the term nutrition. A thorough discussion of the processes ought properly to deal with each organ individually. However, we will consider the matter, generally as it will interest the student of physical training who wishes to understand by what mean or processes new muscle is built and strength is developed.

It is necessary to supply the body with certain elements, in order to properly maintain it. These elements are generally supposed to consist of water, mineral salts, and organic bodies, (proteins, carbohydrates, and fats); it is not, however, altogether certain that this enumeration fully expresses the needs of the body. In experiments upon animals, failures to maintain them have been noted upon a diet containing these elements in proper proportion. Our knowledge of the exact needs of the body is limited, as we have no direct means of establishing the exact elements appropriated by the body and the manner in which it is accomplished. It is from our examination of the food taken into the body, and a close check on the various waste products eliminated that we derive our knowledge of the nutritive needs. The food we eat is utilized partly to repair the tissue waste, and partly to furnish bodily heat and muscular energy. It is practically immaterial, so far as the body heat and muscular energy is concerned, whether the energy is provided by carbohydrates, fats, or proteins; the essential point is that the quantity of food into energy is much the same way as though the same foods were burned outside the body, with the same amount of waste products left. Heat, mechanical and chemical work are all produced therefrom. The food is prepared by the mouth and stomach, passes into the small intestine where the greater amount of assimilation takes place. The nourishing elements are absorbed by the blood and carried to the venae cavae and thence to the right auricle of the heart. The various internal organs and glands all have a part to play in bringing about the proper chemical mixture of the blood. The nutritive elements are carried on through the vascular system and picked up by the cells as needed. A healthy digestion and assimilation of food is dependent upon vigorous circulatory and respiratory functions.

By simply eating the proper foods you cannot expect to maintain a healthy condition of life; nor by breathing alone. In addition, one must lead an active life, strenuous physical exertion being most important to properly and thoroughly stimulate the circulation. I trust you thus appreciate the necessity of vigorous circulation to carry blood through each of the essential functions of nutrition. As we have explained elsewhere, the proper aeration of the blood demands sufficient oxygen, thus encouraging deep breathing. As the oxygen demand takes place in the tissues throughout the body, the mere act of breathing deeply without strenuous exertion accomplishes nothing. You must exercise vigorously, using the entire body to create a want of oxygen; the heart beat is quickened and the breathing becomes deeper. The result is a better nourished condition of the entire body. We can also understand the result of such activities upon the brain. A sluggish., impoverished stagnant blood stream cannot maintain health in any part of the body, while a vigorous circulation of pure blood (which has been thoroughly oxygenized) results in a better nourishment of the brain as well as of the entire body.

Leading authorities in physiology have proven the existence of hunger or the demand for food to be seated in the cells throughout the body, rather than in the stomach. Cutting off the food supply of animals, so that food could not enter the system, regardless of how much was eaten, the hunger continued. The seat of oxygen demand has been established in a like manner by experiments on animals, whereby the want of oxygen has been definitely proven to lie in the tissues; by preventing the blood from flowing from the heart; the animal would breathe violently in an attempt to aerate his blood, showing that the mere presence of oxygen in the lungs was of no value so far as the need of oxygen in the system was concerned. Convulsive efforts at breathing have also been observed after profuse hemorrhage, showing the demand for oxygen on the part of the tissues caused violent breathing, which could not be satisfied due to the shortage of blood to carry oxygen throughout the system.

As to proving the real sense of hunger to be located in the system rather than in the stomach, it has been observed in the case of persons as well as animals with serious injury to the small intestines so as to make impossible the proper passage of food, that regardless of the quantity of food eaten the hunger would be persistent. Of course, a local satisfaction would take place immediately upon filling the stomach, which would soon pass when the systemic requirements were not met. On the other hand, a well nourished person in good health and with an abundance of reserve nourishment in the blood may abstain from food for a considerable time without becoming unduly hungry.

After duly considering all of the foregoing concerning the nutrition of the body - respiration, circulation, and the digestive and assimilative processes, we can better understand the reason for the value of bar bell exercise and strenuous lifting. The demand for vigorous internal functions is stimulated, and by resting for long periods between the periods of exertion, we succeed in better nourishing the body.

The muscles are capable of storing up a chemical substance, glycogen, which is formed by the liver. This chemical substance accumulation is increased by regular physical exercise, and when the muscular tissue cells increase in size and strength, it is undoubtedly through the accumulation of this chemical substance, glycogen.

The tissues do not multiply, nor do the cells, but they do increase in size in the manner just described. It must be understood that these accumulations are separately every minute. This energy storage is consumed through oxygenation. Muscular size is increased in another, though more indirect way.

There is an important physiological bearing on the acceleration of the venous circulation by contraction of muscles, on the nutrition. It is apparently necessary that the supply of blood should be increased in a muscle, in proportion to and during its activity; for at that time its destructive assimilation is undoubtedly augmented, and there is an increased demand on the blood to supply the waste. It is apparently a provision of nature that the activity of a muscle facilitating the passage of blood in its veins, and consequently its flow from the capillaries, induces an increased supply of the nutrient fluid. As the development of tissues is generally in proportion to their vascularity, this may account for the increase in the development of muscle, which is the invariable result of exercise.



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