Work and recreation in their relation to health / by S. Holgate Owen.

  • Owen, S. Holgate.
Date:
[between 1870 and 1879?]
Catalogue details

Licence: Public Domain Mark

Credit: Work and recreation in their relation to health / by S. Holgate Owen. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    that the channels themselves are enabled to widen or contract, and thus admit more or less blood to the part, according to the • amount of energy given out by that part at different times. It may be the brain, or a muscle, or the stomach, which at any moment is doing more work than usual; there is perhaps some extra strain thrown upon it; and just at that time there takes place a widening of the blood channels of the working organ, and an extra supply of blood is furnished—of course, at the expense of some other part that does not happen to be busy at the same moment. You are all familiar with the feeling of external chilliness which sometimes comes on after a good meal; and there is a popular saying, If you eat till you're cold, you will live to grow old, meaning, of course, that this sensation is a sign of good digestion. Well, I am not prepared to admit that; but there can be little doubt that the sensation of chilliness under these circumstances is in some degree owing to the large withdrawal of blood from the surface of the body to meet a larger demand in the digestive organs. What purpose then does the blood serve to our working body, and why is it suppHed in this peculiar manner ? After the account I have given you of its wonderful distribution you must be pre- pared to find that it plays a most essential part in the production of energy. It is, in fact, the medium through which, by the arteries, ^ potential energy, in the form of food and oxygen, is brought to the different tissues, there to be transformed into the actual energy of rnechanical work and heat. It also carries to the tissues nutrient matter to repair their waste, and at the same time, by the veins, it carries away from these tissues those waste or refuse matters which always result from their activity. All the energy put forth by our body is chiefly expended in two ways—as heat, and as mechanical work—and it is derived entirely from two sources—the oxygen we breathe and the food we eat. It does not lie within my province this evening to attempt to explain to you how this wonderful transformation takes place—how the latent or potential energy of food is changed into actual force. What you know so well with regard to the production of mechanical work in an ordinary machine is, let me tell you, just as true in the case of our human body, namely, that whenever there is heat and motion produced there must be suppHed force from without in the form of fuel and oxygen. Let us look at what takes place in a muscle, such as the biceps of the arm, when it performs a stroke of work. What we can see is a shortening of the muscle, which looks rounder and more bulging than before, and a corresponding