Search -
Year-book of medicine, surgery and their allied sciences. 1864
Yearbook of medicine surgery and their allied sciences 1864 Author:Unknown Author Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: or great vessels; (4) a nervous condition not caused by anemia. ('Comptes Rendus,' 1864, i, p. 196.) in. Cieouiation. Influence of the gaseous contents of ... more »the Blood on the activity of the Heart.—L. Thiry's experiments lead him to the conclusion that blood which is wanting in oxygen influences the heart through irritation of tho vagi. This is in opposition to Franke's view, that CO., in the blood is a powerful stimulant to the motor nerves of the heart. If in a rabbit, whose heart is exposed, the access of air to the lungs is cut otf, the left cavities may be seen to fill with dark-red blood, without any alteration taking place in its action; a few seconds later, that is at the time when the unaerated blood reaches the capillaries, including those of tho medulla oblongata and the origin of the vagi, the heart begins suddenly to beat more slowly, and after a few contractions either stands still in tho diastole or pulsates 011)3' a 'on intervals. Up to this time no symptoms of dyspnoea are exhibited; they occur first during the quiescence of the heart. At last general convulsions set in, and the heart, which hitherto had dilated only gradually and to a moderate amount (probably through relaxation), is now suddenly greatly distended. These phenomena occur in the course of about 10 seconds. If artificial respiration is now established the heart again begins to pulsate, but not immediately; only after it has been filled with bright-red blood, and this has been driven further by its isolated contractile movements, does it begin, often quite suddenly, again to beat with a frequency and force nearly equal to that which it possessed at first. It follows that the action of the heart is stopped and renewed, not by the influence of the blood upon the heart itself, but by its effect upon ...« less