Arterial blood

“ When this obstruction of the circulation by uric or carbonic acid prevails throughout the body, the blood pressure is too high in the arterial blood vessels and in the interior organs, such as heart, lungs, brain, etc., and too low in the surface, the extremities and in the venous circulation. The return flow of the blood to the heart through the veins is sluggish and stagnant because the force from behind, that is, the arterial blood pressure, is obstructed by the uric acid which clogs the minute capillaries that form the connection between the arterial and the venous systems. ”

“ The arterial blood is brought from the lungs by two wide, thin-walled pulmonary veins, Fig. 58, V.p.s., V.p.d. They leave the lungs somewhat caudad to their middle region, near the point of entrance of the bronchii and the pulmonary arteries, pass mediad in a direction almost at right angles to the long axis of the body, and enter the left auricle at the same point.
Blood leaves the heart through five large vessels: (1) the pulmonary artery, (2) the two aortic arches, (3) the right subclavian, (4) the primary carotid. ”

“ Only the blood of man must be used. The direct giving of blood by connecting the radial artery of a relation to the median vein of a patient has been used as a means of effecting restoration. Blood may be withdrawn from the system slowly to the extent of 4 %, rapidly to the extent of 2 % of the body weight, without lowering the arterial pressure, owing to the compensatory contraction of the arterioles and the rapid absorption of fluid from the tissues into the blood. The withdrawal of the tissue-lymph excites extreme thirst and the great need for water which occurs after severe hemorrhage. ”

“ But this deficiency of arterial blood may be depending on a more positive cause, venous congestion, impeding its flow; for in sleep, the breathing being slower, the blood becomes essentially darker. Even arterial blood itself will become to a certain degree carbonized, by lentor, or stagnation. Venous congestion and diminution of arterial circulation are not incompatible ”

“ First, the blood is incessantly transmitted by the action of the heart from the vena cava to the arteries in such quantity that it cannot be supplied from the ingesta, and in such a manner that the whole must very quickly pass through the organ; second, the blood under the influence of the arterial pulse enters and is impelled in a continuous, equable, and incessant stream through every part and member of the body, in much larger quantity than were sufficient for nutrition, or than the whole mass of fluids could supply ”

“ A sufficiency of blood to distend it collects within the venous cistern. The arterial system, owin to its elasticity and contractility, empties. If the heart now begin to beat, blood is taken from the venous system and is driven into the arterial system., The arteries receive more blood than can escape through the capillary vessels, and the arterial side of the system becomes distended, until equilibrium is reached, and as much blood escapes into the venous side per unit of time as is delivered by the heart. ”

“ Nothing is more simple, as you perceive, than to distinguish an artery from a vein; you have only to ascertain what is inside of it. When the blood goes out to our organs to nourish them, it is arterial; when it is returning back after having nourished them, it has become venous. But what—you will ask—is it going to do now at the heart, towards which it is on its road? It is going to seek there a fresh impetus which shall send it once more into the lungs, where it will again become arterial, i. e. and once more capable of affording nourishment to the organs. ”

“ The arterial tissue is no exception to this rule, and we have already shown that certain changes normally take place as the individual grows older, changes which are arteriosclerotic in type and are quite like those caused in younger people by many of the etiologic factors of the disease.
We are absolutely dependent upon the integrity of our hearts and blood vessels for the maintenance of activity and span of life. Respiration may cease and be carried on artificially for many hours while the heart continues to beat. ”

“ Servetus, in 1553, [4] had asserted that the blood finds access from the right side of the heart to the left through the lungs, thus explaining the intermixture in the heart of the two kinds of blood appropriate to arteries and veins respectively. For a long time the partition between the ventricles was believed to be perforated like a sieve, so that a mixture of venous and arterial blood could take place. ”

“ By which it clearly appears that the artery is dilated with the impulse of the blood; for of itself it would not throw the blood to such a distance and whilst it was dilating; it ought rather to draw air into its cavity through the wound, were those things true that are commonly stated concerning the uses of the arteries. Do not let the thickness of the arterial tunics impose upon us, and lead us to conclude that the pulsative property proceeds along them from the heart For in several animals the arteries do not apparently differ from the veins ”

“ The great majority presented distinct thickening of the arterial walls. As I suggested in our study of the etiology, these pathological changes appear to be the result of malnutrition of structures (the myocardium, valves and arteries) worked at high pressure; and in addition to the local disturbance of metabolism in the cardiac and arterial walls, which are fed with gouty blood, there is the damaging effect on them of similar disease of the vasa vasorum and vasa cordis or coronaries. ”

“ The blood is subject in the veins to retarding causes, similar to those which operate in the arteries, but perhaps not in an equal degree; for the flexures are less frequent in the veins than in the arteries. As the capacity of the arterial tube increases with its distance from the heart, the velocity, from this cause, as has already been observed, is continually diminished ”

“ We can not ignore the part which heredity plays. The various factors to be considered in the production of the acquired form of arteriosclerosis appear to me to be but contributory factors to a very great extent, the essential and fundamental factor being the quality of arterial tissue with which the individual is endowed.
Arteriosclerosis may occur in infants. Cases have been reported of calcification of the arteries in infants and children. The arteriosclerosis may occur without nephritis or rise of blood pressure. ”

“ It is not a necessary consequence that because there is less blood in the arteries the arterial pressure will be diminished, or the venous pressure increased because the veins contain more than their normal amount of blood, seeing that the blood pressure depends upon many different factors. ”

“ In arterial hæmorrhage the blood is bright red in colour, and escapes from the cardiac end of the divided vessel in pulsating jets synchronously with the systole of the heart. In vascular parts—for example the face—both ends of a divided artery bleed freely. The blood flowing from an artery may be dark in colour if the respiration is impeded. When the heart's action is weak and the blood tension low the flow may appear to be continuous and not in jets. The blood from a divided artery at the bottom of a deep wound, escapes on the surface in a steady flow. ”

“ The retrogressive changes of advancing years can not be rightly termed disease, yet it becomes necessary to regard them as such, for the senile changes, as we shall see, may be but the advanced stages of true arteriosclerosis. Much depends on the nature of the arterial tissue and much [33] on the factors at work tending to injure the tissue. A man of forty years may therefore have the calcified, pipe stem arteries of a man of eighty. Our parents determine, to great extent, the kind of tissue with which we start life. The arteries are elastic tubes capable of much stretching and abuse. ”

“ The muscular arterioles throughout the body by their tonus serve to keep up the normal blood pressure and to distribute the blood evenly to the various organs. Contraction of a large area of arterioles increases the blood pressure and, strangely enough, the arteries respond to increased arterial pressure, not by dilatation, but by contraction. It would appear that rise of blood pressure tends to throw increased work upon the musculature of the arterioles. This may be sufficient only to cause them to hypertrophy, but further strain may easily lead to exhaustion and to dilatation. ”

“ They are nothing in the explanation of the phenomena of health and disease. Let us, then, be content with this general assertion, that the venous capacity surpasses the arterial. It may be said, that in a given time there is more blood in one than the other. ”

“ When there is a sudden rise in the blood-pressure in the arteries, due to vasomotor spasm of the peripheral systemic arterioles, and the heart-walls are strong and well nourished, palpitation is evoked; when the coronary branches are involved in the vasomotor spasm then angina is produced, and the heart-walls, acutely distended with blood, can scarcely contract in the face of the opposition presented to their contraction by the high arterial tension. ”

“ If in old age, ossification exists only in the arteries, the circulation is unaffected; if at the origin of the aorta or in the heart, it is irregular. An artery might become a bony canal, and the blood would circulate there as usual, with the difference only of pulsation. What I have said of the chronic affections of the heart may be said of the acute ones. Syncope arrests its motion, it arrests also the pulse. Certain passions, as anger, fear, &c. seem to be a stimulant to it; they hasten also the arterial motion. All kinds of inflammation of the pericardium affect the pulse. ”

“ In the last years, the system with red blood is remarkable for the following phenomena.
The number of the arterial ramifications is much diminished. As the heart loses its energy, it sends less blood, and with less force. The general vibration that it produces in the whole arterial tree, is less felt at the extremi374ties of this tree. The small vessels that form these extremities gradually contract, are obliterated and become so many little ligaments. ”

“ The most dreaded of all the ills of the cardiac and vascular systems nowadays seems to be arterio-sclerosis, or hardening of the arteries. It is possible for a man of forty-odd, like Mr. Pitts, to have arteries in a condition which would not be encountered normally in persons under seventy years of age.
"The hard or hardening artery means increased blood pressure, with a consequent increased strain on the heart. ”

“ From these facts it is easy for any careful observer to learn that the blood enters an extremity by the arteries; for when they are effectively compressed nothing is DRAWN to the member; the hand preserves its color; nothing flows into it, neither is it distended; but when the pressure is diminished, as it is with the bleeding fillet, it is manifest that the blood is instantly thrown in with force, for then the hand begins to swell; which is as much as to say that when the arteries pulsate the blood is flowing through them, as it is when the moderately tight ligature is applied ”

“ The cause is most probably to be sought in the anemia which results from the narrowing of the channels through which the blood reaches the part. The stiff, much narrowed arteries allow sufficient blood to pass along for the nutrition of the part at rest or in quiet motion. Just as soon as more violent exercise is taken, calling for more blood, an ischemia of the part supervenes, for the stiff vessels can not accommodate themselves to changes in the necessary vascularity of the part. ”