Question

1) What happens first in response to fluid loss in the ECF (e.g., dehydration)? What

happens next?

2) What is tubular deamination and how can it help correct problems with acid/base

balance?

Answer 1

Ans 1. The decrease in extracellular fluid volume is associated with loss of sodium. This is generally due to burns, diarrhoea and use of diuretics.

Because the movement of water is from a region of lower to a region of higher osmotic pressure, the water will flows out of the cells into the extracellular fluid. This will lower its osmotic pressure and increase its volume toward normal. Due to this phenomena,the flow of water out of the cells, and the cells will become dehydrated.

If dehydration continues, Cellular malfunctioning will be observed. A decreased thirst sensation, a decrease in blood pressure and lightheadedness can occur. Due to absence of proper urine formation, the toxic metabolite would not get cleared out of the body. They will feature kidney protein leading to kidney failure.

Ans 2 When glutamine is converted into glutamic acid, ammonia is formed. Another ammonia molecule.is obtained by deamination of glutamic acid into glutamic acid (tubular deamination).

The concentration of ammonium Iona increases with an increase in the acidity of urine. The introduction of hydrogen ions increase the production of ammonium ions by tubular cells. The so formed ammoinum is excreted in urine along with chloride and sulphate ions.This leads to retention of sodium and potassium.ions in the renal cells. This mechanism compensates and corrects acid vale imbalance (by securing and preventing of excretion of sodium and /or potassium ions until steady state is maintained).