Question

Urinary System Review Questions

1: How do you predict whether this sample is hyper- osmotic, hypo-osmotic or iso-osmotic to the extra cellular fluid (ECF) and how do you predict whether the kidney is reabsorbing proportionately more solute or more water from the filtrate?

2:How do you predict whether the production of urine of a particular hydrogen ion concentration has to increase or decrease the hydrogen ion concentration of the ECF

3:Explain why protein is not normally present in urine although it is a major constituent of plasma and list two situations where presence of protein in the urine is normal

4:State whether there is likely to be a higher or lower concentration of ketone bodies in the urine of an individual who is starving or is an untreated diabetic

Answer 1

1) A solution is said to be isotonic when it has osmolarity similar to that solution is equal to ECF, and Hypo-osmotic when less than osmolarity of ECF and hyper-osmotic when more than osmolarity of ECG. Simple Osmosis experiments can be used to predict whether the solution sample is Isotonic or Hypotoni or Hypertonic.

When a cell is suspended in a solution, osmosis occurs and at equilibrium cell’s volume change in response to the solution :

If cell volume at equilibrium has increased -  solution is Hypotonic to the cell.

If cell volume at equilibrium has decreased,- solution is hypertonic to the cell.

If cell volume at equilibrium has not changed, solution is  isotonic to the cell.

To predict whether the kidney is reabsorbing proportionately more solute or more water from the filtrate : We need to see the specific gravity of the urine.

If the specific gravity of urine is incresing this means urine has more solute compared to water, hence kidney is reabsorbing more water compared to solute.

If urine is having less specific gravity, it means less kidney is absorbing less water compared to solute.

2) It can be predicted by pH of the urine. If the pH is decreased - i.e. more H+ is lost in the urine i.e. this has decreased the H+ ion concentration of ECF

If the pH of urine has increased - Less H+ in urine i.e. increased H+ ion concentration in ECF.

3) As Plasma proteins are larger in size and also they posses negative charge thery are not filtered normally in the glomerulus and hence absent in urine.

Glomerular Membrane Permeability Depends on :
Size of particle: Neutral substances which are < 4 nm are freely fltered; > 8 nm are not fltered.
Charge of the particle: as fltration membrane are negatively charged, fltration of positively charged particles is facilitated and negatively charged particles are repelled.

Physiologically Plasma protein can be present in urine in - Vigrous Exercise, Pregnancy

4)  There is likely to be a HIGHER concentration of ketone bodies in the urine of an individual who is starving or is an untreated diabetic.