There are three types of macroglia:

Oligodendrocytes

Schwann cells

Astrocytes

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#Id: 2566

#Unit 7. System Physiology – Animal

Tubular reabsorption is quantitatively large & highly selective.

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#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.

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#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.

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#Unit 7. System Physiology – Animal

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

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#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

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#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.