Elements of human physiology / by Ernest H. Starling.

  • Starling, Ernest Henry, 1866-1927.
Date:
1895
Catalogue details

Licence: Public Domain Mark

Credit: Elements of human physiology / by Ernest H. Starling. Source: Wellcome Collection.

    28/502 (page 16)
    cells of the tissues taking up oxygen and giving up COg to the blood. The cells also discharge their nitrogenous waste products into the blood, which immediately carries them to the kidneys. In these organs, again, we find a single layer of cells between the blood-capillaries and a cavity which is in free communication with the exterior, and it is these cells which take up the waste products of the other tissues from the blood and discharge them into the urinary tubule, to- gether with water and salts, as urine. From the urinary tubule the urine flows down the ureter into the bladder, whence it is voided periodically. Thus the blood is continually taking up food from the alimentary canal and oxygen from the lungs, and carrying them to the tissues. Here it parts with them and receives in exchange the products of tissue change (which are, indeed, only the products formed by the union of the oxygen with the foodstuffs), and, carrying these away, discharges them on the exterior of the body by means of the lungs and kidneys. Muscular Tissues Eetaining our comparison of the human body with a heat engine, we have still the most important part of the mechanism to consider, namely, that part in which the heat produced by the oxygenation of the food is converted into motion and so performs work. This is effected by specialised groups of cells united together to form the muscles. These are fleshy masses attached at two ends to the bones and other supporting tissues of the body. They are capable under certain circumstances of shortening, that is to say, approximating the points to which their two ends are attached against resistance, so that they do work. Thus the biceps muscle of the arm is attached above to