Question
In which of the following secretions is the least amount of sodium present?
| A. |
Duodenal fluid
|
| B. |
Saliva
|
| C. |
Gastric juice
|
| D. |
Ileal fluid
|
Show Answer
|
Correct Answer � B
Explanation
|
|
Sodium Content in GI Secretions
– Sodium varies widely across GI fluids.
– Saliva has the lowest sodium because:
– Salivary ducts actively reabsorb Na⁺.
– Saliva becomes hypotonic by reabsorbing Na⁺ & Cl⁻ and secreting K⁺ & HCO₃⁻.
– At low flow, Na⁺ concentration is especially low.
Typical Sodium Concentrations (Approximate):
– Saliva: 10–70 mEq/L (lowest)
– Gastric juice: 50–70 mEq/L
– Duodenal fluid: ~140 mEq/L (similar to plasma)
– Ileal fluid: ~120–140 mEq/L
