Diuretics Flashcards
Test 3
What do diuretics treat?
HTN
Edema
Diuretics and ______ are used interchangeably
Natriuretic
Diuretics increase _____ volume while Natriuretics increase __________ secretrion
Urine
Sodium ion (which increases water secretion)
Increasing urine output, decreases ______ and decreases blood pressure
blood volume
What is the functional unit of the kidney?
Nephron
Where does a nephron start?
The Glomerulus which is located in the cortex
What happens in the nephrons?
- blood is filtered
- water, ions, and glucose are reabsorbed
- urine is produced & substances are from blood into urine
How many nephrons does each kidney contain?
800,000 to 1,000,000
What is one of the main substances that is secreted by the kidneys and not reabsorbed back into the blood? why?
NH3 – Ammonia
This is a waste product that is filtered by the kidneys. build up can cause coma/death. Therefore its converted to urea (made in the liver) and excreted by the kidneys.
T/F: The medulla is the outer part of the kidney and the cortex is the inner part
F
Switched
Describe the hilus
“hilum”
Center/medial side of the kidney where the renal artery, renal vein, and ureter are located
What structures exit the ureter?
hilum -> ureter -> urinary bladder -> urethra -> exits body
What type of structure is the glomerulus?
capillary
What is “the loop”
The very bottom of the loop of Henle
T/F: The glomerulus is located in the medulla
F
cortex
F/T: The cortex and medulla have different osmolality
T
It effects how much water is reabsorbed back into the urine vs blood
Where is the Loop of Henle?
The medulla
What parts make up the Loop of Henle?
Thick descending -> thin descending -> the loop -> ascending thin -> ascending thick
The proximal and distal _______ tubules are in the _______
convoluted
cortex
Describe the renal corpuscle
Bowman’s capsule
Glomerulus
Where the blood is filtered
Where does the distal tubules dump?
Collecting ducts
T/F: the collecting tubule and ducts are part of the nephron
F
What is the bowman’s capsule?
Epithelial and connective tissues that surrounds the glomerulus capillary structure .
Catches secretions and is the beginning of the nephron
What type of cell provides the filtration in the renal corpuscle?
podocytes
What does protein in the urine mean?
Proteinuria
Podocytes are not permeable to large protein molecules. This indicated problem with the kidneys.
(small proteins can cross)
Where are the Macula Densa Cells located?
Juxtaglomeruler apparatus in the distal tubule; which end up being very close to the glomerulus and the afferent glomerulus artery
What do the Macula Densa Cells do?
Sense Na+ and fluid pressure in the distal tubule
Active the RAA system and regulate blood flow directly into the glomerulus by increasing or decreasing release of NO to juxtaglomerular cells to increase or decrease the size of the afferent artery .
Negative feedback system
_____ artery takes blood into the glomerulus and the ________ takes blood out
afferent
efferent
T/F: Glomerulus is located in the medulla
F
cortex
What capillaries are only found in the cortex in the kidneys? what are they responsible for?
Peritubular capillaries
Filtation & water reabsorption
What capillaries are only found in the medulla in the kidneys?
vasa recta
omsolality changes -> ion reabsorption
What 2 items do we specifically want to be filtered and reabsorbed?
bicarb and glucose
Where does a majority of your reabsorption happen?
Proximal convoluted tubule
How much urine is produced from the filtrate?
1%
What does the juxtaglomerular appartaus consist of?
macula densa
Juxtaglomerular cells
extraglomerular mesanginal cells
What is osmolality?
dissolved substances in a solution
What is the juxtaglomerular cells? where is it located?
-modified epithelial cells that act like smooth muscle
-Communicate with macula dense cells
-contract and dilate to effect blood flow to the glomerulus
Afferent artery
What 3 systems regulate how blood gets into the glomerulus?
Direct renal autoregulation (Juxtaglomerular apparatus)
neural regulation (Activation of SNS and release of Epi and NE)
hormonal regulation (Activation of RAA)
What happens at the proximal tubule?
80% of water and ions are reabsorbed back into blood
-NaHCO3, NaCl, glucose, amino acids, organic solutes, K+, water are reabsorbed
Where do Carbonic anhydrase inhibitors work?
What do they do?
Proximal tubule
Inhibit CA enzyme that allows carbonic acid to be converted to water an CO2 in the lumen-urine
block bicarb reabsorption
Drugs: Caffeine
Diuretic
MOA: blocks adenosine-R in PCT
Describe the function of NHE3 and carbonic anhydrase in sodium and bicarb reabsorption.
Located in the PCT
NHE3: Na+ in the nephron in exchange for H+ in the lumen-urine (water follows Na+)
Carbonic anhydrase: Converts Carbonic acid to water and CO2 to be reabsorbed into the nephron and Carbonic anhydrase converts it to bicarb
Drugs: Acetazolamide
Class: Carbonic Anhydrase inhibitor
MOA: inhibits Carbonic Anhydrase -> blocks sodium bicarb reabsorption -> slows down NHE3 counter-transporter
Uses: Acute mountain sickness, glaucoma, alkalinization of urine
SE: decreased K+, Na+, pH (below 7.35), kidney stones
Where does Acetazolamide work?
Carbonic Anhydrase inhibitor
PCT
What is the osmolality in the cortex?
300
What is the osmolality in the medulla? Why?
400-1200
increased solutes helps with water reabsorption
What type of diuertic is mannitol?
osmotic diuretic
List 5 major types of diuretics and relate them to their sites of action, urinary electrolytes, and main side effects.
Carbonic Anhydrase inhibitors: CA in PCT; bicarb/K+ loss; decreased pH
Loop diuretics: NKCC2 in TAL; Na+/K+/Cl-/Mg++/Ca++ loss; slight alkalosis
Thiazide: NCC (NaCl) in DCT; Na+/Cl- loss; slight alkalosis
omsotic: Mostly PCT but anywhere where water is permeable
Potassium-sparing: inhibit aldolsterone-R in CT;
T/F: Mannitol is reabsorbed into bloodstream
F
impermeable solute
stays in nephron
Mannitol increase _________
osmolality
What area of nephron doesnt have an effect on diuretics?
S2 - straight segment
What is the S2 - straight segment?
Area where some diuretics dont work
area where larger substances can be secreted:
- uric acid
- NSAIDs
- Abx
-Diuretics
Where does water reabsorption happen in the loop of Henle?
Descending
Where is water impermeable in the loop of Henle?
Ascending
What are NKCC2? Where are they?
cotransporter that takes 1Na+, 1K+, 2Cl- into nephron
Ascending Loop of Henle
Describe positive potential
potential in the lumen-urine thats affected by increasing positive charges (increased K+ in the nephron which increases K+ in the lumen-urine) in the lumen urine which drive Mg++ and Ca++ into the blood.
What happens in the ascening loop of Henle?
Na+ moves only.
Impermeable to water
What are the strongest diuretics?
Loop diuretics
What are sulfamide diuretics?
Loop diuretics
Thiazide
How do loop diuretics work?
inhibit NKCC2 cotransporter
prevents reabsorption of Na+/K+/Cl-
What loop diuretic is NOT a sulfamide?
Ethacrynic acid
What are my K-wasting diuretics?
Carbonic anhydrase inhibitors
loop diuretics
thiazide
Drug: Furosemide
Loop Diuretic
Inhibits NKCC2 in TAL
Sulfa allergies
Secrete: Na, K, Cl, Mg, Ca
Causes slight alkalosis
Drug: Ethacrynic acid
Loop Diuretic
Inhibits NKCC2 in TAL
Not a Sulfa Drug!!!
Secrete: Na, K, Cl, Mg, Ca
Causes slight alkalosis
What do Thiazide drugs work?
inhibit the NCC (NaCl- cotransporter) in the Distal Convoluted tubule
Also inhibit Ca++ activity
Is the thiazide prototype?
Hydrochlorothiazide
What is the final site for sodium reabsorption in water reabsorption?
Collecting tubule
What happens at the collecting tubule?
-Final site for sodium reabsorption
-Important site for potassium secretion
-Site for influence of aldosterone
Where are the principal and intercalated cells?
Collecting tubules
What is aldosterone’s role in the nephron at the collecting tubule?
diffuses into nephron at CT
binds with its receptor
increases ENaC (Na+ ion channel) activity
increases Na+ reabsorption
increases blood volume
this contributes to (-) lumen charge
Drugs: Spironolactone
Potassium-sparing diuretic
inhibit aldosterone-R in CT
Drugs: Amiloride
Potassium-sparing diuretic
inhibit ENaC (Na+ ion) channels
Define “potassium wasting”.
increased excretion of potassium in the urine, which can occur with certain diuretics
Explain the mechanism of potassium and bicarb wasting in the collecting tubule following specific diuretic administration
Carbonic anhydrase inhibitors block the enzyme responsible for converting carbonic acid to water and CO2.
This can cause potassium and bicarbonate wasting in the collecting tubule by blocking sodium-bicarbonate reabsorption in the proximal tubule, leading to increased delivery of sodium and bicarbonate to the collecting tubule, which then promotes potassium and bicarbonate excretion.
What are the 2 drugs that reduce potassium loss during sodium diuresis
Spirolactone
Amiloride
What do potassium sparing diuretics help with?
Spirolactone only.
Adrenal cortex overproducing alderosterone
-Conn’s syndrome
-Ectopic ACTH production
CHF
Nephrotic syndrome
use of K-wasting diuretics
T/F: You want to use Potassium-sparing diuretics in combo with a K-wasting diuretic
T
Drug: ADH/Vasopressin
Works in the Collecting Duct
Adds more Aquaporin channels to increase water reabsorption
increases blood volume (Increases BP) and concentrates urine
Drug: Conivaptan
Potassium-sparing diuretic
Works in the collecting duct
ADH Antagonist
Drug: Mannitol
Osmotic diuretic
Increases osmolality in nephron
Works in PCT and descending loop
Uses: , increase UO, decrease ICP; removal of renal toxin (rhabdo), after contrast, induce diarrhea (PO)
slight edema and increased Na+ when 1st administered
USE FILTER WHEN CONCENTRATION ABOVE 20%
Discuss the use of diuretics in patients with diabetes insipidus.
DI is the dumping of dilute urine.
ADH/Vasopressin and thiazides diuretics treat this
