Rudiments of animal physiology / [George Hamilton].

  • Hamilton, George, 1808-1885
Date:
1870
Catalogue details

Licence: Public Domain Mark

Credit: Rudiments of animal physiology / [George Hamilton]. Source: Wellcome Collection.

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    undergoes in that course. It will he recollected that the left side of the heart sends the blood into the general system: this is called the systemic circulation. The right 6ide of the heart sends it into the lungs, and this has received the name of the pulmonic circulation. But if the blood that goes to the lungs were returned in the same state as it is sent, death would be the consequence, for venous blood is a poison to the body; and this is the reason why an animal dies when the air is prevented from getting into its windpipe bv hanging or drowning. Bichat showed this very decisively, fie connected, by a tube, the jugular vein of one dog with the carotid artery (which sends the blood to the brain) of another, and allowed the venous blood to flow into it. The immediate effect of this was, that the dog in whose brain the venous blood was made to circu- late, became completely insensible, and would in a short time have died. On allowing the arterial blood, however, again to circulate in its brain, the dog was quickly restored. 72. What are the changes, then, that take place in the lungs, and how are these changes effect- ed 1 These questions will be best answered by first knowing what the lungs are. The lungs (vul- garly called lights) are princi- pally composed, 1st, of air-tubes (bronchi), of which the windpipe (trachea) is the commencement, and which divide and subdivide until they term mate, as has been supposed, in very minute bags or air-vesicles; and 2dly, of the pul- monary artery (Fig. 15, E, and Fig. 10, p, a), which branches out upon the sides of these air-tubes. Fig. 20 shows the windpipe, with the lungs entire on one side, and with the branches of the air-tubes dissected on the other.. These tubes are said to terminate in vesicles, which vary in size from the 50th to the 100th part of an inch in diameter. The lungs are also seen in Fig. 21, in their natural situation in the chest. 73. If we tie up tightly in a bladder a quantity of venous or dark blood, we shulf And, in a short time, that exposure to the air has changed the colour of the portion near the surface. The air has passed through the bladder, and has converted the