Renal 2 Flashcards
where is glucose reabsorbed?
proximal tubule
glucose reabsorption occurs by –
secondary active transport (cotransport) coupled to sodium ion
where is urea reabsorbed?
proximal tubule then distal tubule, cortical collecting duct, and medullary collecting duct
urea reabsorption in the proximal tubule is by –
diffusion, secondary to water removal
As water leaves proximal tubule, urea becomes concentrated and –
diffuses down its concentration gradient from tubular lumen into peritubular capillaries
T/F: urea is just a waste product
false
urea contributes to – in medulla
maintaining the hyperosmotic gradient
Is urea freely filtered?
yes
how does urea move through kidney?
simple and mediated diffusion
approximately 50% of filtered urea is reabsorbed in the proximal tubule it follows –
Na+ and H2O reabsorption
the remaining 50% of urea that is not reabsorbed –
enters loop of Henle
urea that has accumulated in the – is secreted back into thin descending and ascending loops of Henle
inner medulla intersitium
how does urea secreted back into the loop of Henle
facilitated diffusion
– urea is reabsorbed in distal tubule and cortical collecting duct
30%
– urea is reabsorbed in medullary collecting duct
55%
– urea is excreted
15%
cycling traps urea in –
inner medulla
sources of water gain
water from ingestion of liquids and “solid” food and from metabolism
sources of water loss
urine, feces, sweat and insensible loss through skin, lungs and menstruating
sources of Na+ gain
ingestion of food
sources of Na+ loss
urine, feces, and sweat
what is the mechanism of Na+ reabsorption?
Na/K-ATPase pumps sodium of the cell = keeps intracellular [Na+] low –> sodium moves downhill out of lumen into tubular epithelial cells
na+ reabsorption drives the reabsorption of the cotransported substances and the secretion of –
H+
water reabsorption is a – process
passive
