Glucose is primarily absorbed from-

Ans. is 'a' i.e., Proximal convoluted tubule Important educational pointso 60-70% of glomerular filtrate is reabsorbed in proximal tubule.o Na+ reabsorption occurs in all segments of nephron excepting descending limb of loop of Henle . 60% (60-70%) of filtered Na+ is reabsorbed in proximal tubule. About 30% of filtered Na+ is reabsorbed in thick ascending limb of loop of Henle. About 7% of filtered Na+ is reabsorbed in early distal tubules and about 3% of filtered sodium is reabsorbed in late distal tubule and collecting duct.o About 65% (60-70%) of water is reabsorbed in the proximal tubule and about 15% of water is reabsorbed in the thin descending limb. Remaining 20% of water enters the distal tubules and is absorbed from distal tubule and collecting duct according to the homeostatic requirements of the body, under the control of ADH.o All substances (Na+, K+, HCO3, Cl-, Phosphate, Protein, Glucose, water) are maximally absorbed in proximal tubule.o Glucose and amino acids are completely absorbed from proximal tubules along with Na+ as secondary active transport contransport (symport).o H+ is not absorbed by nephrons anywhere it is only secreted (in proximal tubule, late distal tubule and cortical collecting tubules).o Substances which are both secreted and reabsorbed are K+, uric acid and creatinine.o On a normal diet maximum solutes are reabsorbed almost completely : Glucose : 100%, Aminoacids 100%, HCO3-: 100%. Water: 99.4%, Na+: 99.4%, Cl-: 99.2%, Uric acid : 98%, K+ : 93.3%, Urea : 53%, and Total solutes : 98.9%o Amount secreted per day of different filtered contents are : Na+ : 150 mEq/d, K+: 90 mEq/d, Cl- : 150 mEq/d, Glucose: 0, Amino acid: 0, HCO3 : 0, Uric acid: 5 mmol/d. Creatinine: 12 mmol/d, Urea: 410 mmol/d, Water: 1-1.5 L/d; and total solutes : 700 mOsm/d.