MCQ – 89319

This graph depicts the filterability of Dermatan through Kidney.  “1” represents the complete filtration & “0” represents No filtration. Choose substances ”A”, “B”, & “C” respectively.

Correct Answer � A Explanation

Ans. A. Polycationic, Neutral, Polyanionic

The permeability of the glomerular capillaries is about 50 times that of the capillaries in skeletal muscle.

Neutral substances with effective molecular diameters of less than 4 nm are freely filtered, and the filtration of neutral substances with diameters of more than 8 nm approaches zero.

Between these values, filtration is inversely proportional to diameter.

However, sialoproteins in the glomerular capillary wall are negatively charged, and studies with anionically charged and cationically charged dextrans indicate that the negative charges repel negatively charged substances in blood, with the result that filtration of anionic substances 4 nm in diameter is less than half that of neutral substances of the same size.

This probably explains why albumin, with an effective molecular diameter of approximately 7 nm, normally has a glomerular concentration only 0.2% of its plasma concentration rather than the higher concentration that would be expected on the basis of diameter alone; circulating albumin isGanong’s Review of Medical Physiology 23rd Edition Section III Chapter 38 Pg: 646.

negatively charged.

Filtration of cationic substances is greater than that of neutral substances.