Loop of Henle

what does it do x3

lowers the water potential of tissue in the medulla

creates conc grad so water leaves the tubule by osmosis
concentrates urine

descending limb Vs ascending limb x3

descending- narrow, thin walled and permeable to water
ascending- wider, thicker walled and permeable to ions but not water

process of counter current principle x3

Na+ AT of ascending limb
lowers WP in interstitial region
water cannot leave ascending limb as impermeable
descending limb impermeable to water so leaves by osmosis into IR and enters blood capillaries

where is the lowest WP (within filtrate) and effect

at the base of the LOH- Na+ diffuse out

what happens at the DCT

make final adjustments to water and salts that are reabsorbed
control pH by selecting which ions to reabsorb
permeability altered by ADH

what happens at collecting duct

permeable- as filtrate moves down, water leaves by osmosis and enters blood vessels
passed through channel proteins (aquaporins)
ash Inc permeability

what does a longer loop of Henle result in

more Na+ moves out from AL

na+ gradient maintained for longer

WP gradient maintained for longer

more water absorbed from LOH by osmosis