pH of CSF is -
C i.e. 7.33 CSF sugar is 2/3 of plasma sugarQ. So CSF/plasma glucose ratio is -. 0.6667. CSF pH is 7.33Q (less than plasma pH 7.4) and its pressure is maintained by its absorption at arachnoid villQ. Hypehyroidism cause decreased whereas, hypothyroidism/myxoedema is associated with increased CSF protein. Substance CSF concentration Plasma cone CSF/plasma ratio. Mg" 2.2 1.6 1.39 PCO2 50.2 39.5 1.28 Creatinine 1.5 1.2 1.25 Cl- 113 99 1.14 HCO3- 25.1 24.8 1.01 Osmolality 289 289 1 Na' 147 150 0.98 Urea 12 15 0.80 Inorganic-P 3.4 4.7 0.73 Glucose 64 100 0.64 2.9 4.6 0.62 Cat+ 2.3 4.7 0.49 Uric Acid 1.5 0.3 Protein 20 6000 0.003 Cholesterol 0.2 175 0.001 pH 7.33 7.40 Regulation of CSF pressure by arachnid villi - Rate of CSF formation is nearly constant, so it is seldom a factor in pressure control. - Whereas, arachnoid villi function like valves that allow CSF to flow readily into blood in venous sinuses while not allowing blood to flow backward in opposite direction - CSF flow begins when its pressure is 1.5 mmHg higher than the pressure of blood in venous sinuses. The valve opens more widely, when this pressure difference is higher, which in normal conditions never allows CSF pressure to rise more than few mm Hg higher than cerebral venous sinus pressure. - Absorption is propoional to pressure. At a pressure of 112 mm H20, which is average normal CSF pressure, filteration & absorption are equal. Below a pressure of 68 mm H20, absorption stops.
7.13
7.23
7.33
7.4