Renal pathology, diuretics and anesthesia- week 5

Question 1

What is natriuretic peptide?

Answer 1

involved in long-term regulation of sodium and water balance

blood volume

arterial pressure

Question 2

what are the actions of natriuretic peptides?

Answer 2

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

Question 3

Natriuretic peptides serve as a:

Answer 3

counter-regulatory system for the RAAS

Question 4

What is atrial natriuretic peptide?

Answer 4

-produced by atrial myocytes

functions:
-relax smooth muscle
-promote NaCl and water excretion by kidney

Stimuli for release:
-atrial stretch (increased extracellular volume)

Question 5

What are the actions of ANP

Answer 5

-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

Question 6

What is Brain Natriuretic peptide

Answer 6

• 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

Question 7

What are the cv and renal actions of natriuretic peptides?

Answer 7

natiuresis
diuresis
improved GFR
inhibit renin release
decrease angiotensin 2
decrease aldosterone
systemic vasodilation
arterial hypotension
reduced venous pressure
reduced pulm. cap. wedge pressure

Question 8

What is the definition of diuretics?

Answer 8

a substance that increases the rate of urine volume output

Question 9

how do diuretics work?

Answer 9

Act by decreasing the rate of sodium reabsorption from the tubules which causes sodium output to increase natriuresis which then results in water output

Question 10

what are the common clinical uses of diuretics?

Answer 10

decrease ecf volume
treat edema
chf
HTN

Question 11

why do diuretics stop working?

Answer 11

decreased ECF= decreased MAP = decreased GFR= increased renin= angiotensin 2

Question 12

Most diuretics produce diuresis by:

Answer 12

inhibiting the reabsorption of sodium at different segments of the renal tubular system

Question 13

what diuretics work in PCT?

Answer 13

carbonic anhydrase inhibitors

Question 14

where do loop diuretics work?

Answer 14

TAL

Question 15

where do K+ sparing diuretics work?

Answer 15

collecting duct

Question 16

Where do thiazides work?

Answer 16

DCT

Question 17

What are osmotic diuretics?

Answer 17

urea or mannitol

draw fluid into tubules

Question 18

what are loop diuretics?

Answer 18

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

Question 19

What are the thiazide diuretics?

Answer 19

hydrochlorathiazide (HCTZ)

most used diuretic

action inhibit sodium chloride reabsorption in early distal convoluted tubule

-hypokalemia
-metabolic alkalosis

Question 20

What are carbonic anhydrase inhibitors?

Answer 20

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

Question 21

what are aldosterone antagonists?

Answer 21

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.

Question 22

Na+ channel blockers

Answer 22

amiloride and triamterene

action: decrease activity of na/K atpase in collecting tubules and thereby decrease Na+ reabsorption

-spare potassium

Question 23

What is the leading cause of end-stage renal disease (ESRD)

Answer 23

Diabetes mellitus

HTN

Question 24

How does kidney disease happen?

Answer 24

-decrease number of nephrons
-hypertrophy of surviving nephrons
-increase glomerular pressure
-glomerular sclerosis

Question 25

what is AKI?

Answer 25

abrupt loss of kidney function within a few days

severe AKI where the kidneys may abruptly stop working entirely or almost entirely

pts w AKI may eventually recover

Question 26

What is chronic kidney disease?

Answer 26

irreversible decrease in number of functional nephrons

Question 27

categories of acute renal failure

Answer 27

pre-renal

intra-renal

post-renal

Question 28

what is pre-renal

Answer 28

kidney not getting enough blood flow and becomes ischemia

ex HF, hypovolemia

Question 29

What is intra-renal?

Answer 29

damage to kidney itself

ex: toxins, infections, autoimmune, direct renal injury

Question 30

what is post-renal?

Answer 30

obstruction of the collecting system

ex: stones, urethral valves, tied off ureter, kinked foley

Question 31

when do symptoms of chronic kidney disease occur?

Answer 31

Symptoms often don’t occur until the number of functioning nephrons decreases to at least 70% below normal

Question 32

what is CKD defined as?

Answer 32

presence of kidney damage or decreased kidney function for at least 3 months

Question 33

when can normal blood concentrations and electrolytes no longer be maintained?

Answer 33

until the number of functioning nephrons decreases below 20-25% of normal