United States or Zimbabwe ? Vote for the TOP Country of the Week !
The essential lesion is the absence or deficiency of valves, so that they are incompetent and fail to support the column of blood which bears back upon them. Normally the valves in the femoral and iliac veins and in the inferior vena cava are imperfectly developed, so that in the erect posture the great saphena receives a large share of the backward pressure of the column of venous blood.
As arterial and venous blood are in a perpetual state of alternate conversion into one another, the question arises, in what circumstances the protoxide of iron is capable of being converted into the peroxide, and vice versâ.
In blood, however venous, there is in health always some oxygen; and in even the brightest arterial blood there is actually more carbonic acid than oxygen." T. H. Huxley. "Consumption is a disease which can be taken from others, and is not simply caused by colds. A cold may make it easier to take the disease. It is usually caused by germs which enter the body with the air breathed.
Imperfect circulation is an important causative factor in ulceration, especially when it is the venous return that is defective. This is best illustrated in the so-called leg ulcer, which occurs most frequently on the front and medial aspect of the lower third of the leg.
Venous pressure was not much affected by small doses of epinephrin, but with large doses it rose from 10 to 80 mm. Pituitary extract acts somewhat similarly to epinephrin. Caffein, though raising the arterial pressure, did not influence the venous pressure. Strychnin did not raise either pressure until the dose was sufficient to cause muscular contractions.
Thus the two circulations of the venous blood to the lungs, and of the oxygenated blood over the body, are more and more separated until, in higher reptiles, they become entirely distinct. As the animal came on land and breathed the air, more completely oxygenated blood was carried to the organs, and their activity was greatly heightened.
Having parted thus with its impurities, the venous blood ebbed back again from the right ventricle into the venous system. But for a small fraction of the venous blood that entered the right ventricle another fate was reserved.
As the food can not become a part of the living animal, or the venous blood regain its lost properties until they have undergone the requisite changes in the air-cells of the lungs, the function of respiration by which these are effected is one of pre-eminent importance in the animal economy, and well deserves the most careful examination.
The first symptoms of weakening of the compensation are irregularity in the beat and venous congestion of the head and face, causing bluing of the lips, often nosebleed, and sometimes hemoptysis and insomnia. Later the usual series of disturbances from dilatation of the right ventricle occurs.
Miss Poppit came up the street and Miss Mapp put up her illustrated paper again, with the revolting picture of the Brighton sea-nymphs turned towards the window. Peeping out behind it, she observed that Miss Poppit's basket was apparently oozing with bright venous blood, and felt certain that she had bought red currants. That, coupled with the ice, made conjecture complete.
Word Of The Day