Respiration / by J.S. Haldane and J.G. Priestley.

  • John Scott Haldane
Date:
1935
Catalogue details

Licence: Public Domain Mark

Credit: Respiration / by J.S. Haldane and J.G. Priestley. Source: Wellcome Collection.

    446/534 (page 408)
    blood-pressure; but soon the blood-pressure is restored. The first effect of the bleeding is probably to evoke partial compensation by a pressor excitation of the vasomotor centre. This is probably due to diminished circulation-rate and consequent fall in oxygen-pressure and increase of C02-pressure in the medulla, although the pressor reaction is limited in the manner already explained. The blood- Fig. 117. Blood-volumes of rabbits in c.e. of blood per 100 grammes of body- weight (Boycott). The curve shows what the blood-volumes would be if they varied in the proportion of body-surface to body-weight. The dots show average results of actual determinations by the modified Welcker method. The numbers indicate the number of determinations for each group of observations. volume is soon more or less restored by taking up of liquid from the tissues and intestines. The blood is thus diluted; but the diluted blood fills up the blood-vessels and completely restores the blood- pressure. After a delay of many days, or perhaps several weeks, the hydraemic blood is restored to normal by reproduction of the missing corpuscles. Similarly, when blood is transfused from another animal of the same species, there is at first a rise of both venous and arterial blood- pressure. Soon, however, the volume of blood is reduced by dis¬ appearance of most of the extra plasma. The remaining blood then contains an excess of red corpuscles, and these are only got rid of in the course of some days or weeks.