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step 2: tubular reabsorption

Terms in this set (23)

quickly reclaims most of tubular contents and returns them to blood
tubular reabsorption
water and ion reabsorption is regulated by
hormones
two routes of tubular reabsorption
transcellular and paracellular
tubular reabsorption involves
active and passive transport
solute enters apical membrane, travels through cytosol, exits via basolateral membrane, and enters blood
transcellular route
solute travels between tubule cells via tight junctions
paracellular route
most abundant cation in filtrate
sodium (Na+)
transport of sodium across basolateral membrane of cell is via
primary active transport
pumps sodium into interstitial space from basolateral membrane
sodium potassium pump
transport of sodium across apical surface of cell is via
secondary active transport (cotransport) or facilitated diffusion
active pumping of sodium at basolateral membrane results in
strong electrochemical gradient in cell
electrochemical gradient of sodium results in
low intracellular sodium that leads to sodium diffusion
sodium reabsorption by primary active transport provides
energy and means for reabsorbing almost every other substance
organic nutrients reabsorbed by secondary active transport are
cotransported with sodium
organic nutrients that are cotransported with sodium
glucose, amino acids, some ions, vitamins
movement of sodium and other solutes creates
osmotic gradient for water
water is reabsorbed by osmosis, aided by water filled pores called
aquaporins
movement of sodium and other solutes creates osmotic gradient for water
passive tubular reabsorption of water
solute concentration in filtrate increases as
water is reabsorbed
increased solute concentration creates concentration gradients for solutes which
drive their entry into cells and capillaries
fat soluble substances, some ions, and urea will follow
water
transcellular transport systems are
specific and limited
when carriers for a solute are saturated, excess solutes are
excreted in urine
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