A nervous, smoking male, age 36 years, is admitted to hospital with severe hunge

Question

A nervous, smoking male, age 36 years, is admitted to hospital with severe hunger Epigastric pain reduced by eating, acid hiccups, diarrhoea, and steatorrhoea (ie, fatty stools). He has a stressful work, and over the last months he has frequently used drugs containing acetyl salicylic acid for headache, and used whisky on the rocks. Radiological examination of the stomach and duodenum suggests the presence of an ulcer in the duodenal bulb. This is confirmed by endoscopy. Gastric juice is removed by aspiration. The basal rate of HCl secretion is found to be 5 times normal. Histological examination of the gastric mucosa reveals a higher density of parietal cells and gastric glands than normal, but no hyperplasia of antral G cells.

The serum [gastrin] of the patient is 10 times higher than normal, and does not increase following a test meal.

One dose of the proton pump blocker, Omeprazole, reduces the HCl secretion rate of the patient to normal for 24 hours.

Question:

Transportation of one mol of H+ from the cytosol of the parietal cell to the gastric lumen costs at least an oxidation of 30 mmol of glucose. Calculate the free energy necessary for the active transport of one mol of H+.

Explanation / Answer

To transport 1 mol of H+, we require energy equivalent to oxidation of 30 mmol of glucose.

Therefore, we need to calculate the energy associated with the oxidation of glucose.

Free energy associated with the oxidation of 1 mole of Glucose is given by the Gibbs Free Energy equation:

G = H-TS

Where,

G = Free energy

H = Change in enthalpy = 2816kJ/mol

T = Temperature in Kelvin = Normal body temperature = 37oC = 310 Kelvin

S = Change in Entropy = +181J/molK = 0.181 KJ/molK

Therefore,

G = (-2816kJ/mol)-(310K X 0.181 KJ/molK)

G = -2872.11 kJ/mol

This is the Free energy associated with the oxidation of 1 mole of Glucose.

Therefore,

For oxidation of 30 mmole of Glucose, Free energy is,

G = -2872.11 X 30/1000

G = 86.1633 kJ

G = 86163.3 Joules

Thank you!

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