Sleep and sleeplessness / [J. Mortimer Granville].

  • Granville, J. Mortimer (Joseph Mortimer), 1833-1900
Date:
1879
Catalogue details

Licence: Public Domain Mark

Credit: Sleep and sleeplessness / [J. Mortimer Granville]. Source: Wellcome Collection.

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    a network permeating- every region of the body, and bringing the blood into due relation with the tissues which require to be nourished. The quantity of the fluid admitted to any organ or tissue depends in large measure on the calibre of the smaller arteries, or arterioles, which bring the blood to the local network, and their size is regulated by the action of a special system of nerves which act upon these vessels, and either cause them to contract so as to admit only a small stream, or relax to allow a larger volume to pass. The nerves ful- filling this important function are directly influenced by the activity of the part, so that when the organ is inactive the supply is reduced. The tissues are endowed with a power of taking up from the blood just what they require, allowing the rest to pass on. If the demands of an org'an are large, or the blood flows to it in too small quantity, there will be a reflex nerve action to procure more rapid supply, and the flow will be quickened and the size of the vessels enlarged. When an organ is in morbid action the commotion occasioned is so great that the general pulsation is accelerated, and while what is called “ inflammation” occurs in the organ, “ fever,” or febrile excitement, is set up through- out the body. The brain is in the same position as regards blood supply as every other organ, and