Directions for Laboratory Work in Physiology for the Use of Medical Students
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. 1920 edition. Excerpt: ...vein, gradually open clamp 2, (produce vaso-dilation in the skin vessels); then screw down clamp 2, (cause vaso-contriction in the skin). Repeat the experiment with the drum running, and record the changes in pressure in the renal artery. Close clamp 2, which is to be opened only in this test. /. Some Clinical Applications. By varying the rate of pumping, the volume pumped, and the peripheral resistance, one can imitate a number of interesting phenomena. 1. Effect of Vagus Inhibition. By vagus inhibition the heart is stopped, then occasional beats are seen, then, when the inhibition ceases, the heart beats gradually faster until a rate somewhat higher than normal is reached (to compensate for the low pressure), and then returns to its normal rate. To test these effects, adjust machine to normal conditions, pump at rate of once in two seconds, let drum run, and after about ten seconds produce the inhibition effects by altering the rate of pumping. 2. Action of Depressor Nerve. This nerve starts at the root of the aorta, where it is excited by a pressure higher than normal. It acts to inhibit the vaso-constrictor center in the medulla and possibly to excite the vaso-dilator center, and so causes vaso-dilation. The action can be readily imitated by pumping at a regular rate, and after the normal pressure is obtained, lessening the peripheral resistance in the small arteries gradually, clamp 1 being used. 3. Traube-Hering Waves. These waves are caused by rhythmic action of the vaso-constrictor center. Record 3 waves. 4. Nitrite of Amyl. This drug acts on the muscles of the walls of the arteries, causing them to dilate. As the dilation occurs the heart beat quickens to compensate for the fall of blood pressure. During the pumping produce a gradual...
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