A Laboratory Guide in Pharmacology (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1917 Excerpt: ...students C and D, pumping and outflow; students E and F, recording. Outflow (at v.). Arterial pressure. Venous preure. (Time required Max. Min. Max. Min. fori00cc.) 1. (Norma ) Pump with moderate excursions; at rate of 60 per minute. The capillaries-clamp is partly closed 2. (Vagus Stimulation) Pump at the rate of 10 per minute, allowing complete relaxation, but incomplete contraction Falls. Falls. Falls. 3. (Vagus Depression) Pump at the rate of 120 per minute, but with very weak compres-sion Little rise. Little rise. Little rise. Fig. 28.--Artificial circulation model. The heart is represented by a rubber syringe bulb with valves in the direction of the arrow. This is compressed by a lemon-squeezer. The vessels are formed by rubber tubing, that for the aorta being especially elastic. The arterial pressure is taken on a mercury manometer; the vein pressure by an upright tube filled with water. The capillary resistance is furnished by a screw-clamp. The dimensions of the apparatus are indicated on the figure. Technical References Artificial Circulation Schemes, Tigerstedt, 2.4, 319. CHAPTER XXXVI EXCISED AND FROG HEARTS INTRODUCTORY The Heart Muscle.--Automat icily.--The cardiac muscle differs from other muscle by the fact that it contracts rhythmically by an inherent property, i. e., even in the absence of nervous impulses.1 This property is sometimes called the automatic motor mechanism of the heart. If the heart is weakened, it may be lost so that the heart may respond to stimulation by a single contraction, just like ordinary muscle. On the other hand, the rhythmic property may be imparted to ordinary muscle; for instance, by immersing it in certain solutions of NaCl. The rhythmic property, therefore, does not constitute a fundamental distinction betwee...