A textbook of human physiology / translated from [the] 6th German edition by W. Stirling.

  • Landois, Leonard
Date:
1888
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Licence: Public Domain Mark

Credit: A textbook of human physiology / translated from [the] 6th German edition by W. Stirling. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

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    by the right carotid, right subclavian, the two coronary arteries, and the aorta below the origin of the innominate artery. He estimated that with every systole of the heart, 172 cubic centi- metres (equal to 180 gianiines) of blood were discharged into the aorta; this, thcrefoi-e, must be the capacity of the left ventricle (compare § 83). 92. THE DURATION OF THE CIRCULATION.—The time required by the blood to make a complete circuit through the course of the circulation was first de- termined by Hering (1829) in the horse. He injected a 2 per cent, solution of potas- sium ferrocyanide into a special vein, and ascertained (by means of ferric chloride) when this substance appeared in the blood taken from the corresponding vein on the opposite side of the body. The ferrocyanide may also be injected into the central or cardiac end of the jugular vein, and the time noted at which its presence is detected in the blood of the peripheral end of the same vein. Vierordt (1858) improved this method by placing under the corresponding vein of the opposite side a rotating disc, on which was fixed a number of cups at regular intervals. The first appearance of the potassium ferrocyanide is detected by adding ferric chloride to the serum which separates from the samples of blood after they have stood for a time. The duration of the circulation is as follows :— Horse, . . 31 5 seconds. I Hedgehog, . 7 61 seconds. ] Duck. . . 10'64 seconds. Dog, . . 16-7 ., I Cat, . . 6-69 ,, Buzzard, . 673 ., Rabbit, . . 779 ,, ! Goose, . 10-86 ,, | Fowl, . . 5-17 ,, Results.—When these numbers are compared with the frequency of the normal pulse-beat in the corresponding animals, the following deductions are obtained :— (1) The mean time required for the circulation is accomplished during 27 heart- beats, i.e., for man = 322 seconds, supposing the heart to beat 72 times per minute. (2) Generally, the mean time for the circulation in two warm-blooded animals is inversely as the frequency of the pulse-beats. Modifying Conditions.—The time is influenced by the following factors :— 1. Long vascular channels (e.g., from the metatarsal vein of one foot to the other foot) re- quire a longer time than short channels (as between the jugulars). The difi'ereiice may be equal to 10 per cent, of the time required to complete the entire circuit. 2. In young animals (with shorter vascular channels and higher pulse-rate) the time is shorter than in old animals. 3. Eapid and energetic cardiac contractions (as during muscular exercise) diminish the time. Hence rapid and at the same time less energetic contractions (as after section of both vagi), and slow but vigorous systoles {e.g., after slight stimulation of the vagus), have no effect. C. Vierordt estimated the quantity of blood in a man, in the following manner :—In all warm-blooded animals, 27 systoles correspond to the time for completing the circulation. Hence, the total mass of the blood must be equal to 27 times the capacity of the ventricle, i.e., in man, 187-5 grms. x 27 = 5062-5 grnis. This is equal to j\j of the body-weight in a persoji weighing 65-8 kilos, (compare § 49). It is not to be forgotten that the salt used is to some extent poisonous, but Hermann uses the <;orres]»oiiding innocuous soda salt (25 per cent). Pathological.—The duration of the circulation seems to be increased duiin<^ septic fever IVolff). ' ^ 93. WORK OF THE HEART.—The left ventricle expels 0-188 kilo, of blood with each systole, and in doing so it overcomes the pressure in the aorta, which is equal to a column of blood 3-21 metres in height. [The amount of blood expelled from each ventricle during the systole is about 180 grms. (6 oz.). It is forced out against a pressure of 2.50 mm. Hg. = 3-21 metres of blood.] The work of the heart at each systole is 0-188 x 3*21 =0-604 kilogramme-metre. If the number of beats = 75 per minute, then the work of the left ventricle in 24 hours = (0*604 x 7b X 60 X 24) = 65,230 kilogramme-metres ; while the work done by the riqhf ventricle is about one-third that of the left, and therefore = 21,740 kiloo-ramme- metres. Both ventricles do work equal to 86,970 kilogramme-metres. A workman during eight hours produces 300,000 kilogramme-metres, i.e., about four times as
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