AP BIOLOGY

Detailed explanation-1: -The proximal tubules reabsorb about 65% of water, sodium, potassium and chloride, 100% of glucose, 100% amino acids, and 85-90% of bicarbonate. This reabsorption occurs due to the presence of channels on the basolateral (facing the interstitium) and apical membranes (facing the tubular lumen).

Detailed explanation-2: -Reabsorption of water and specific solutes occurs to varying degrees over the entire length of the renal tubule. Bulk reabsorption, which is not under hormonal control, occurs largely in the proximal tubule. Over 70% the filtrate is reabsorbed here.

Detailed explanation-3: -Selective reabsorption takes place in the proximal convoluted tubule (PCT) of the kidney. It is the process by which certain substances that are required by the body (such as glucose, amino acids, vitamins and water) but have been filtered out of the blood during ultrafiltration, are reabsorbed.

Detailed explanation-4: -Proximal tubules are responsible for reabsorbing approximately 65% of filtered load and most, if not all, of filtered amino acids, glucose, solutes, and low molecular weight proteins. Proximal tubules also play a key role in regulating acid-base balance by reabsorbing approximately 80% of filtered bicarbonate.