diuretics Flashcards
what are diuretics?
Agents that work along various sites of nephron to increase water excretion by increasing urine volume
Primarily act by inhibiting Na+ reabsorp. from the nephron into circulation
can also affect other ions including magnesium, calcium, chloride, and bicarbonate
Drugs that affect ______ have the greatest effect on urine volume & are most powerful diuretics
sodium transport
If lose a positive charge in urine (Na+, sodium, a cation) body sends a negative charge ______ after it to _______
negative charge (Cl-, HCO3-) to keep body and urine neutral
Nephron is the ________ unit of the kidney and has the following 4 parts:
smallest filtering unit (filtering blood, making urine) parts-coming from the glomerulus... Proximal tubule Loop of Henle Distal convoluted tubule Collecting ducts (collecting tubules)
what does the proximal convoluted tubule reabsorb?
Reabsorbs:
All :Glucose and Amino acids
Most: Na+, H20, K+ , other ions (HCO3-, Cl-, PO43-)and Uric acid
(65-80% of sodium reabsorbed here)
body can’t reabsorb ____ so ____ breaks it down into H20 and CO2
carbonic acid, carbonic anyhydrase (CA)
happens in the proximal convoluted tubule as well as outside it in the lumen (urine)
thin descending limb: impermeable to _____
thick ascending limb: impermeable to _____ but absorbs
thin descending: Na+ …inc. Na+ in lumen
thick ascending: H2O but absorbs Na+, K+, Cl-
in the thick ascending limb..H20 is reabsorbed is by activating _______
At end have a lot of _____ & a little _____ in lumen
Makes urine _______ as it ascends
Na+/K+/2Cl- cotransporter system
lot of H2O and little Na+
less concentrated
what happens at the distal convoluted tubule?
Reabsorbs Na+, Cl- to make urine fully dilute
Parathyroid hormone (PTH)- increases Ca2+/Na+ exchange leading to increased Ca2+ reabsorption - little sodium reabsorb.
what happens in the collecting tubule?
aldosterone regulates reabsorption of Na+ in exchange for secreting K+ and H+
ADH (anti-diuretic hormone/vasopressin): Acts on V2 receptor to open H20 channels to increase H20 reabsorption into collecting tubule
why do we need to use anti diuretics for organ failure? what happens if diuretics do their job too well for patients with liver failure… renal failure… HF?
need to use anti diuretics for major organ failure b/c they have increased fluid levels (hypervolemia), but if they work too well …
Liver failure (cirrhosis)-Excess diuresis causes encephalopathy
Renal failure- if remove too much fluid kidneys can fail worse
Heart failure-take off too much fluid, kidneys can fail
what electrolytes are used in making urine?
Potassium Sodium Magnesium Calcium Chloride
which diuretics can increase pH and excretion of Mg, Na, and K?
thiazides and loops
which diuretics can decrease pH and inc. excretion of Na (mildly) ?
potassium sparing and Carbonic Anyhydrase inhibitors
which agents excrete Na the best?
loops and osmotics
