One major problem is that this approach does not take species frequency of occurrence or relative abundance into account.

TLS Online TPP Program

#Id: 2566

#Unit 7. System Physiology – Animal

Tubular reabsorption is quantitatively large & highly selective.

TLS Online TPP Program

#Id: 2567

#Unit 7. System Physiology – Animal

Reabsorption

Water and many solutes (e.g., Na+, Cl−, HCO3−, glucose, amino acids, urea, Ca2+, Mg2+, phosphate, lactate & citrate) are reabsorbed from the glomerular filtrate into the peritubular capillary blood.

TLS Online TPP Program

#Id: 2568

#Unit 7. System Physiology – Animal

Secretion

A few substances (e.g., organic acids,

organic bases, K+) are secreted from peritubular capillary blood into tubular fluid for excreting substances in the urine.

TLS Online TPP Program

#Id: 2569

#Unit 7. System Physiology – Animal

The mechanisms for reabsorption involve transporters in the membranes of the renal epithelial cells.

TLS Online TPP Program

#Id: 2570

#Unit 7. System Physiology – Animal

For a substance to be reabsorbed, it must first be transported

Across the tubular epithelial membranes into

the renal interstitial fluid and then

Through the peritubular capillary membrane back into the blood

TLS Online TPP Program

#Id: 2571

#Unit 7. System Physiology – Animal

Transcellular Pathway

Water and solutes can be transported through the cell membranes by passive diffusion or active transport.