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Unformatted text preview: At any one time only about s-t}% of capillaries have blood flowing through them Regulated bY: . Amount of blood coming from arteries and arterioles . Contraction of smooth muscle in precaPillary sPhincters Exchange of substances between blood and interstitial fluid across the thin endothelium of capillary walls . Simple solutes (e'g. 02, CO2, sugars, salts) diffuse across cells or through spaces between cells . Movement is aided bY "bulk flow" of fluid driven bY blood Pressure in capillary being >>>> then osmotic pressure (O.P.) . At far end of capillary, accumulation of large proteins increases O.P. and fluid moves back into caPillary . About 85% of fluid is recovered in this way 7. The lymphatic system works with the circulatorY system Lymphatic System returns fluid and proteins to blood (and also has functions in immunity) Fig' 43.7 l...
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- Fall '10