Compared with plasma, which of the following constituents is present at a HIGHER concentration in normal cerebrospinal fluid?
- A Chloride ✓
- B Protein
- C Glucose
- D Potassium
Correct answer: A. Chloride
Explanation
CSF is a relative ultrafiltrate modified by active secretion. Chloride is higher in CSF (about 116 to 122 mEq/L) than in plasma (about 100 to 106 mEq/L), reflecting Donnan equilibrium across the negatively charged proteoglycan matrix. Glucose is roughly two thirds of the plasma level, protein is far lower (15 to 45 mg/dL versus about 7000 mg/dL), and potassium is slightly lower than in plasma.
Reference: Ganong's Review of Medical Physiology, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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