Diuretics pt. 1 (Exam III) Flashcards
Differentiate a diuretic from a natriuretic.
Diuretic = ↑ Urination
Natriuretic = ↑ Na⁺ secretion → ↑ H₂O secretion.
What’s the name of a drug that specifically targets H₂O loss?
Aquaretic
What are the end goals for diuretics in general?
↓ Blood volume = ↓ HTN
or ↓ edema
What component of our blood buffer system can be lost through diuretic use?
What can occur when imbalances of this component occur?
- HCO₃⁻
- Metabolic Acidosis/Alkalosis
What are the 5 classes of diuretics?
- Carbonic Anhydrase Inhibitors
- Loop Diuretics
- Thiazides
- K⁺-Sparing Diuretics
- H₂O Excretion Altering Agents
How many nephrons does a normal human kidney contain?
800,000 - 1,000,000
What are the 3 prinicipal activities of nephrons in producing urine?
- Filtration
- Reabsorption
- Secretion
The Glomerulus, Bowman’s Capsule, Proximal Convoluted Tubule (PCT) and Distal Convoluted Tubule (DCT) are all located in what major region of the kidney?
Renal Cortex
Differentiate Glomerulus and Bowman’s Capsule.
- Glomerulus = capillary network inside Bowman’s Capsule
- Bowman’s Capsule = Nephron tissue surrounding glomerulus. (collects filtrate from glomerulus)
Where is the first space where blood “interacts” with urine and where the majority of fluid absorption into the urinary system occurs?
Glomerulus and Bowman’s Capsule
What are the components of the renal corpuscle?
Glomerulus and Bowman’s Capsule
What are the three components of the renal tubule?
- Proximal Convoluted Tubule (PCT)
- Loop of Henle
- Distal Convoluted Tubule (DCT)
What is the name of the area where afferent and efferent arterioles enter/exit the renal corpuscle?
Vascular Pole
Dilation of afferent arterioles results in _________.
↑ GFR
What is the urinary pole?
Area where filtrate in Bowman’s Capsule enters the PCT.
The capillary networks that wraps around the PCT and DCT is called what?
Peritubular Capillaries
The capillary network that wraps around the Loop of Henle is known as what?
Vasa Recta
How much of our urinary filtrate is produced in the Bowman’s Capsule?
100%
How much of filtrate is reabsorbed in the PCT?
80%
How much of filtrate is reabsorbed in the Loop of Henle?
6%
How much of filtrate is reabsorbed in the DCT?
9%
How much of filtrate is reabsorbed in the Collecting Tubule?
4%
For every 100ml of blood that is filtered, how much urine is created?
1ml of urine
What are the three components of the Juxtaglomerular Apparatus?
- Macula Densa
- Juxtaglomerular Cells
- Extraglomerular Mesanginal Cells
Where is the Juxtaglomerular Apparatus located?
Vascular Pole of the Renal Corpuscle.
Where are the Macula Densa cells located? What other structure do they touch?
- Ascending Limb of the Loop of Henle
- Juxtaglomerular cells of the afferent arteriole
What do the Macula Densa cells do?
- Monitor Osmolality and fluid volume of DCT
- Transmit signals to JG cells.
Where are our juxtaglomerular cells located?
What type of cell are they?
What do they do in response to stimuli?
- Afferent arteriole of the renal corpuscle.
- Modified smooth muscle cell
- Synthesize Renin
Though the PCT reabsorbs many different parts of the filtrate, in lecture we were told to focus on two specific things. What are these two things that the PCT reabsorbs?
- NaHCO₃
- NaCl
What is the mechanism of action of Carbonic Anhydrase Inhibitors?
Blocking reabsorption of NaHCO₃ in the PCT.
How does caffeine affect urine output?
- Caffeine weakly blocks adenosine receptors in PCT
- Blocked adenosine receptors = ↑ UO
What does adenosine binding to receptors in the PCT do?
Adenosine binding in the PCT will ↓ UO.
(Because adenosine presence means we need to conserve energy, creating urine is energy intensive.)
Which transporter(s) starts the cycle in the PCT to preserve HCO₃⁻ ?
How does it start the above stated cycle?
NHE3 Apical Surface Transporter
NHE3 exchanges Na⁺ for H⁺
In the HCO₃⁻ Retention cycle of the PCT, what occurs to the H⁺ once its placed into the urine by the NHE3 transporter?
H⁺ binds to HCO₃⁻ forming H₂CO₃
What enzyme cleaves H₂CO₃ into CO₂ + O₂ ?
What occurs if this enzyme is inhibited?
CA (Carbonic Anhydrase)
- HCO₃⁻ is lost to the urine
- NHE3 affected = Na⁺ loss
What is the only CA Inhibitor still in use?
Acetazolamide
What are Acetazolamides effects on:
1. NaCl
2. NaHCO₃
3. K⁺
4. pH
- ↓ serum NaCl
- ↓↓↓ NaHCO₃
- ↓ K⁺
- Metabolic Acidosis ( HCO₃⁻ loss )
What is normal serum osmolality?
What is the osmalality in the deepest parts of the renal medulla?
300 mOsm/kg
1200 mOsm/kg
What is the osmolality of the renal cortex?
Variable: 100-300 mOsm/kg
Which drug is an impermeable solute that works by drawing H₂O to it throughout the nephron?
When is this drug reabsorbed from the urine into the blood stream?
Mannitol
Mannitol does not get reabsorbed.
What does the S2 segment of the PCT have in comparison to other parts of the nephron?
Protein Transporters
What occurs in the descending limb of the Loop of Henle?
What characteristic does the tissue have that makes this occur here?
H₂O reabsorption
Hypertonic medullary interstitium
Which portion of the Loop of Henle is impermeable to H₂O ?
Thick Ascending Limb (TIL)
How are Mg⁺⁺ and Ca⁺⁺ reabsorbed in the Thick Ascending Limb?
- K⁺ is moved from ICF to urine.
- K⁺ excess makes urine + charged.
- Positively (+) charged urine drives Mg⁺⁺ and Ca⁺⁺ through pericellular route to blood interstitium.
Would the loop of Henle have a relatively low or high osmolality?
↑ Osmolality
Which transporter moves NaCl and K⁺ into the ICF of the Thick Ascending Limb?
NKCC2
Which diuretic class inhibits NaCl reabsorption in the Thick Ascending Limb (TAL) ?
Which transporter is blocked to achieve this effect?
Loop Diuretics (Furosemide)
NKCC2
Which diuretics can’t be used if one is allergic to -sulfa drugs?
What might be a good alternative to this class if a -sulfa allergy is present?
Loop Diuretics (Furosemide, etc.)
Ethacrynic Acid (Loop diuretic w/ no sulfa)
Which diuretic class is useful as it is the most efficacious class and also does not cause metabolic acidosis?
Loop Diuretics
How does furosemide increase secretion (loss through urine) of Mg⁺⁺ and Ca⁺⁺ ?
- ↓ NaCl reabsorption
- K⁺ ICF concentration ↓
- Urine + decreases
- No + urine = ↓ movement of Mg⁺⁺ and Ca⁺⁺
What type of bodily pH might result from Loop diuretic administration?
Is there HCO₃⁻ loss from this drug class?
Slight Alkalosis
No HCO₃⁻ loss
