- Water and electrolytes like Na+ and cl– are lost from the body in diarrhoea. Oral
administration of NaCl solution in this condition does not improve the situation. When glucose is administered with normal NaCl solution through oral route, the absorption of electrolytes along
with water occurs and the patient recovers.
A. Glucose enhances ATP production in the mucosal cells of small intestine and thus facilitates sodium absorption.
B. Glucose inhibits the diarrheal toxin induced cAMP production in the mucosal cells of small intestine.
C. Na+ is co-transported with glucose on the apical surface of the mucosal cells of small intestine.
D. The epithelial sodium channels (ENaC) are activated by glucose in colon.
Which one of the following is true?
(1) Only A (2) A and B
(3) Only C (4) C and D
Diarrhea results in significant loss of water and essential electrolytes like sodium (Na⁺) and chloride (Cl⁻) from the body, leading to dehydration and electrolyte imbalance. Oral rehydration therapy (ORT), which involves electrolytes combined with glucose, is a lifesaving treatment that restores these losses by promoting absorption in the intestine. Understanding the physiological mechanism underlying this process clarifies why glucose is critical for effective rehydration.
Why NaCl Solution Alone Does Not Work Effectively
Oral administration of sodium chloride (NaCl) solution alone during diarrhea is insufficient to improve hydration significantly because the absorption of sodium and water from the intestine is impaired when diarrheal toxins increase cyclic AMP (cAMP) and disrupt normal ion transport.
Role of Glucose in Enhancing Electrolyte and Water Absorption
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Sodium-Glucose Co-Transport (SGLT1):
Glucose is absorbed into intestinal enterocytes via sodium-glucose co-transporters (SGLT1) on the apical surface of mucosal cells. This process simultaneously transports Na⁺ along with glucose into the cells. The co-transport utilizes the sodium gradient maintained by the Na⁺/K⁺-ATPase on the basolateral membrane, allowing efficient uptake against concentration gradients. -
Water Movement:
The active transport of sodium and glucose creates an osmotic gradient that drives passive water absorption, restoring body hydration.
Evaluating the Given Statements
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A. Glucose enhances ATP production in mucosal cells and facilitates sodium absorption:
This is not the primary mechanism; glucose absorption itself is sodium-dependent and energy-driven indirectly by Na⁺/K⁺-ATPase but not through direct ATP production enhancement by glucose. -
B. Glucose inhibits diarrheal toxin-induced cAMP production:
No evidence supports glucose directly inhibiting cAMP production induced by diarrheal toxins. -
C. Na⁺ is co-transported with glucose at the apical surface of mucosal cells:
True. SGLT1 mediates sodium and glucose co-transport into enterocytes, which is the cornerstone of oral rehydration therapy effectiveness. -
D. Epithelial sodium channels (ENaC) are activated by glucose in colon:
ENaC channels are present in the colon and are involved in sodium absorption regulated by aldosterone, but their activation is not directly linked to glucose presence.
Summary Table: Statements and Validity
Statement Truth Value Explanation A. Glucose enhances ATP production False Glucose absorption depends on Na⁺ gradient, not ATP looping B. Glucose inhibits diarrheal toxin cAMP False No direct inhibition of cAMP documented C. Na⁺ co-transported with glucose on apical surface True SGLT1 cotransporter mediates this crucial absorption process D. ENaC activated by glucose in colon False No direct activation of ENaC by glucose reported Conclusion
The correct and physiologically accurate statement explaining glucose’s role in enhancing absorption during diarrhea is:
Na⁺ is co-transported with glucose on the apical surface of the mucosal cells of the small intestine.Therefore, the best answer is:
(3) Only CThis mechanism forms the scientific basis for oral rehydration therapy, which remains a cornerstone treatment for dehydration caused by diarrhea worldwide.The correct explanation is that sodium (Na⁺) is co-transported with glucose on the apical surface of the mucosal cells of the small intestine via the sodium-glucose co-transporter (SGLT1). This co-transport facilitates the absorption of Na⁺ along with glucose, and water follows osmotically, leading to effective rehydration during diarrhea.
Among the options, the true statement is:
(3) Only C -
