Question

When a person is dehydrated, hypotonic fluid will be found in the
A. Loop of Henle
B. Collecting duct
C. PCT
D. DCT

Answer 1

Dehydration is the process of loss of water from the body which may occur through excess sweating, diarrhoea etc and reabsorption of hypotonic fluids occurs. A hypotonic fluid has less concentration of solute and has more amount of water.

Complete answer:
Dehydration occurs when free water loss exceeds free water intake in the body.
In hypotonic fluids where fluid goes into the cell making it swell i.e., solution containing a lower concentration of solute than the fluid inside the cell i.e., they are basically diluted fluids having less salt and more water than the body fluids.

Hypotonic fluid will be present in the loop of Henle when a person is dehydrated. A loop of henle is a part of the kidney tubule, forming a long loop in the medulla of the kidney from which the blood reabsorbs water and salts. Thus the process of reabsorption occurs in the thick ascending limb and about 25% of sodium and potassium will be reabsorbed through the walls of the ascending limb of the loop of Henle through sodium/potassium/chloride which is a three ion cotransporter and the sodium/potassium ATPase which maintains the concentration gradient of sodium.

Hence, the correct answer is option (A).

Additional information:
Fluids can leave the body in many different ways
2 types of fluid loss
• Sensible water loss (measurable): Through vomiting, urine and diarrhoea
• Insensible water loss (not measurable): Respiration and sweating

Fluids are of 3 types
• Isotonic fluids: Here the solutions have got same osmolality as the body fluids
• Hypotonic fluids: The solutions are more diluted of they have a lower osmolarity than the body fluids
• Hypertonic fluids: These are the solutions which are more concentrated or have a osmolality higher than the body fluids

Note: In order to treat dehydration hypotonic fluids are intravenously given to the patients. Hypertonic fluids are prescribed for hyponatremia i.e., low sodium concentration. The extracellular fluid volume could be increased by isotonic solution.