Download The Anatomy and Physiology of Capillaries Book in PDF, Epub and Kindle
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1922 edition. Excerpt: ... LECTURE VI THE REACTIONS OF CAPILLARIES TO STIMULI (CONTINUED) Capillary poisons. AS a type of substances which show a selective / action on the contractile elements of the capiljLlary wall Heubner has studied the gold salt, AuCl4Na + 2H2O, and describes the effects of an intravenous injection of a lethal dose of this substance in mammals (rabbit, cat and dog). The lethal dose for a rabbit is about 15 mg. per kg. body weight. For the carnivora it is about three times as high. The arterial pressure begins to fall during the injection and continues to fall, reaching zero in a few minutes (not above ten), when the animal dies, though the heartbeat may continue for a short time afterwards. At autopsy the parenchymatous organs, as also the lungs and muscles, appeared to contain an abnormal quantity of blood, and bleedings from minute vessels were frequent. The intestines, especially the empty stomach, duodenum and jejunum, of the carnivora were abnormally injected with numerous patches of a deep red in the mucosa, in spite of the fact that the animals had been without food for a day before being used for the experiments. In several cases considerable quantities of blood were found in the abdominal cavity, though no macroscopic wounds could be detected. The microscopic examination of the organs showed dilated and very numerous capillaries and dilated venules and very numerous microscopic bleedings from capillaries and venules, especially in the liver, lungs and kidneys. The small arteries were everywhere contracted, in most cases even to obliteration of the lumen. These post-mortem observations, together with the sudden fall of arterial pressure preceding death, show clearly that we have to do with a relaxation of the capillaries and venules...