biochem dwuggy1 Flashcards
natriuresis
excretion of sodium in urine via action of kidneys
(decreases Na+ conc. in blood)
acid-base balance in kidney
kidneys excrete acidic or alkaline urine (depending on body’s need)
when is formation of acidic urine required
to compensate for body’s tendency to decrease body pH due to metabolic production of CO2 (glycolysis)
how is k+ balance in kidney critical
even small changes in extracellular k+ concentrations affects the function of excitable cells
how does excretion of organic ions work and where is energy derived from
involves active transport
(energy from action of Na+/K+ATPase on basolateral membrane)
how do diuretics work on kidneys
increase volume of urine produced by promoting exretion of Na+, Cl-, HCO3 and water from kidneys
net result of diuretics on kidney
increased urine flow, altered pH and altered ionic composition of blood and urine
what are diuretics used for treating
oedema & hypertension
site and mechanism of action for diuretics
osmotic diuretics
carbonic anhydrase inhibitors
loop diuretic
thiazide
k+ sparing diuretics
osmotic diuretic (mannitol)
na ions taken up into tubule cell, water can’t flow in usual amount, less na+ conc, less na+ reabsorp,
blood volume decreased
large volume of dilute urine produced
what should osmotic pressure be when your body does nor need to conserve water
lumen = cell = interstitium
osmotic diuretic indications (mannitol)
promotes:
- diuresis, especially in the prevention of acute renal failure from, eg, increased pigment load due to transfusion reaction
- excretion of toxic substances.
osmotic diuretic indications (isosorbide, urea, glycerin mannitol)
reduce intraocular pressure
osmotic diuretic indications (urea and mannitol)
approved to reduce intracranial pressure and cerebral oedema
why is mannitol preferred over other osmotic diuretic agents
inherently non-toxic
freely filtered
non-reabsorbable
not metabolised
other agents may pass into cells to a limited extent
