Question

Which values reflect the expected glucose concentrations (in mM) in micropuncture samples collected from regions inside a nephron in the following order: Bowman’s capsule, beginning of proximal convoluted tubule, intermediate segment, middle of distal convoluted tubule, and beginning of collecting duct?

a.) 0; 1; 2; 3; 2

b.) 2; 2; 0; 0; 0

c.) 2; 2; 2; 0; 0

d.) 0; 0; 0; 0; 0

Answer 1

Answer

b) 2; 2; 0; 0; 0

Explanation

• Glomerulus is the place where glomerular filtration takes place .All particles except blood cells and proteins are not passed into Bowman's capsule. Thus glucose will be present in the filtrate.Hence glucose concentration will be 2 mM in micropuncture sample taken from Bowman's capsule.
• 100% glucose reabsorption occur in proximal convoluted tubule(PCT) , Thus glucose will be present.Hence glucose concentration will be 2 mM in micropuncture sample taken from  proximal convoluted tubule.
• From Loop of Henle ( intermediate segment) onward, there will be no presence of glucose , because 100% glucose are reabsorbed from PCT. Thus glucose will be absent .Hence glucose concentration will be 0 mM in micropuncture sample taken from  intermediate segment, middle of distal convoluted tubule, and beginning of collecting duct.
• Option A and D are wrong because concentration of glucose in Bowman's capsule is 0mM, which means glucose is not passed through glomerular membrane, which is wrong.
• Option C is wrong because concentration of glucose in intermediate segment is 2 mM , which is wrong because complete reabsorption of glucose takes place in PCT.