. Elements of human physiology. Physiology. LYMPH AND TISSUE-FLUIDS 295 lymph may attain 8 to 10 mm. soda solution. In the thoracic duct, at the point where it opens into the great veins of the neck, the pressure is obviously the same as in these veins, that is to say, from — 4 to 0 mm. Hg, the negative pressure being occasioned by the aspiration of the thorax. This differ- ence of pressure is sufficient to cause a certain amount of flow. It must be remembered however that under normal circumstances no lymph at all flows from a resting limb. The only part of the body which gives a continuous s
. Elements of human physiology. Physiology. LYMPH AND TISSUE-FLUIDS 295 lymph may attain 8 to 10 mm. soda solution. In the thoracic duct, at the point where it opens into the great veins of the neck, the pressure is obviously the same as in these veins, that is to say, from — 4 to 0 mm. Hg, the negative pressure being occasioned by the aspiration of the thorax. This differ- ence of pressure is sufficient to cause a certain amount of flow. It must be remembered however that under normal circumstances no lymph at all flows from a resting limb. The only part of the body which gives a continuous stream of lymph during rest is the alimentary canal, the lymph in which is poured out into the lacteals, and thence makes its way through the thoracic duct. Movement, active or passive, Fij. A lymi)liatic vessel laid open to show arrangement of the valves. (Testut.) of the limbs at once causes a flow of lymph from them. Since the lymphatics are all provided with valves (Fig. 159), the effect of external pressure on them is to cause the lymph to flow in one direction only, towards the thoracic duct and great veins. Hence we may look upon muscular exertion as the greatest factor in the circulation of lymph. The flow of lymph from the commencement of the thoracic duct in the abdominal cavity to the main part of it in the thoracic cavity is materially aided by the respiratory move- ments ; since, with every inspiration, the lacteals and abdo- minal part of the duct are subjected to a positive pressure, and the intrathoracic part of the duct to a negative pressure, so that lymph is continually being sucked into the latter. The Absorption of Lymph and Tissue-fluids On injecting a coloured solution or suspension into the connective tissues of any part of the body, and gently kneading the part, it is found that the fluid fills all the lymphatic. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - color
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