Renal pathology, diuretics and anesthesia- week 5 Flashcards
(34 cards)
What is natriuretic peptide?
involved in long-term regulation of sodium and water balance
blood volume
arterial pressure
what are the actions of natriuretic peptides?
vasodilator effects- directly dilate veins
-decrease CVP
-Decrease CO
-Decrease preload
dilate arteries- decrease SVR
- increasing GFR and filtration fraction =
-naturesis (increase sodium excretion)
-diuresis
decrease renin release = decreased angiotensin 2 and aldosterone
Natriuretic peptides serve as a:
counter-regulatory system for the RAAS
What is atrial natriuretic peptide?
-produced by atrial myocytes
functions:
-relax smooth muscle
-promote NaCl and water excretion by kidney
Stimuli for release:
-atrial stretch (increased extracellular volume)
What are the actions of ANP
-inhibit renin release
-increased GFR via vasodilation of afferent arteriole and constriction of efferent arteriole
-inhibits aldosterone secretion
-acts directly on collecting duct to decrease sodium chloride reabsorption
-inhibits ADH release from posterior pituitary
What is Brain Natriuretic peptide
- synthesized largely by the ventricles (as well as the brain)
-BNP is released by the same mechanisms that release ANP and has similar physiologic actions
What are the cv and renal actions of natriuretic peptides?
natiuresis
diuresis
improved GFR
inhibit renin release
decrease angiotensin 2
decrease aldosterone
systemic vasodilation
arterial hypotension
reduced venous pressure
reduced pulm. cap. wedge pressure
What is the definition of diuretics?
a substance that increases the rate of urine volume output
how do diuretics work?
Act by decreasing the rate of sodium reabsorption from the tubules which causes sodium output to increase natriuresis which then results in water output
what are the common clinical uses of diuretics?
decrease ecf volume
treat edema
chf
HTN
why do diuretics stop working?
decreased ECF= decreased MAP = decreased GFR= increased renin= angiotensin 2
Most diuretics produce diuresis by:
inhibiting the reabsorption of sodium at different segments of the renal tubular system
what diuretics work in PCT?
carbonic anhydrase inhibitors
where do loop diuretics work?
TAL
where do K+ sparing diuretics work?
collecting duct
Where do thiazides work?
DCT
What are osmotic diuretics?
urea or mannitol
draw fluid into tubules
what are loop diuretics?
furosemide
bumetanide
ethacrynic acid
action: inhibit the na-k-2cl co-transporter in the TAL
countercurrent multiplier system is disrupted and the interstitium cannot become hyperosmolar
What are the thiazide diuretics?
hydrochlorathiazide (HCTZ)
most used diuretic
action inhibit sodium chloride reabsorption in early distal convoluted tubule
-hypokalemia
-metabolic alkalosis
What are carbonic anhydrase inhibitors?
acetazolamide (diamox)
action: reduce reabsorpton of Na+ in the PCT by decreasing HCO3- reabsorption
- main use is tx of glucoma
disadvantage: causes acidosis through bicarb loss in urine
what are aldosterone antagonists?
spironolactone
action: potassium-sparing diuretic
decreases reabsorption of Na+ and K+ secretion by competing for aldosterone binding sites in the distal segment of the distal tubule *
-do not produce hypokalemia (like loop and thiazide)
The reason for this is that by inhibiting aldosterone-sensitive sodium reabsorption, less potassium and hydrogen ion are exchanged for sodium by this transporter and therefore less potassium and hydrogen are lost to the urine.
Na+ channel blockers
amiloride and triamterene
action: decrease activity of na/K atpase in collecting tubules and thereby decrease Na+ reabsorption
-spare potassium
What is the leading cause of end-stage renal disease (ESRD)
Diabetes mellitus
HTN
How does kidney disease happen?
-decrease number of nephrons
-hypertrophy of surviving nephrons
-increase glomerular pressure
-glomerular sclerosis
