Diuretics pt. 1 (Exam III)

Question 1

Differentiate a diuretic from a natriuretic.

Answer 1

Diuretic = ↑ Urination
Natriuretic = ↑ Na⁺ secretion → ↑ H₂O secretion.

Question 2

What’s the name of a drug that specifically targets H₂O loss?

Answer 2

Aquaretic

Question 3

What are the end goals for diuretics in general?

Answer 3

↓ Blood volume = ↓ HTN
or ↓ edema

Question 4

What component of our blood buffer system can be lost through diuretic use?
What can occur when imbalances of this component occur?

Answer 4

• HCO₃⁻
• Metabolic Acidosis/Alkalosis

Question 5

What are the 5 classes of diuretics?

Answer 5

1. Carbonic Anhydrase Inhibitors
2. Loop Diuretics
3. Thiazides
4. K⁺-Sparing Diuretics
5. H₂O Excretion Altering Agents

Question 6

How many nephrons does a normal human kidney contain?

Answer 6

800,000 - 1,000,000

Question 7

What are the 3 prinicipal activities of nephrons in producing urine?

Answer 7

1. Filtration
2. Reabsorption
3. Secretion

Question 8

The Glomerulus, Bowman’s Capsule, Proximal Convoluted Tubule (PCT) and Distal Convoluted Tubule (DCT) are all located in what major region of the kidney?

Answer 8

Renal Cortex

Question 9

Differentiate Glomerulus and Bowman’s Capsule.

Answer 9

• Glomerulus = capillary network inside Bowman’s Capsule
• Bowman’s Capsule = Nephron tissue surrounding glomerulus. (collects filtrate from glomerulus)

Question 10

Where is the first space where blood “interacts” with urine and where the majority of fluid absorption into the urinary system occurs?

Answer 10

Glomerulus and Bowman’s Capsule

Question 11

What are the components of the renal corpuscle?

Answer 11

Glomerulus and Bowman’s Capsule

Question 12

What are the three components of the renal tubule?

Answer 12

1. Proximal Convoluted Tubule (PCT)
2. Loop of Henle
3. Distal Convoluted Tubule (DCT)

Question 13

What is the name of the area where afferent and efferent arterioles enter/exit the renal corpuscle?

Answer 13

Vascular Pole

Question 14

Dilation of afferent arterioles results in _________.

Answer 14

↑ GFR

Question 15

What is the urinary pole?

Answer 15

Area where filtrate in Bowman’s Capsule enters the PCT.

Question 16

The capillary networks that wraps around the PCT and DCT is called what?

Answer 16

Peritubular Capillaries

Question 17

The capillary network that wraps around the Loop of Henle is known as what?

Answer 17

Vasa Recta

Question 18

How much of our urinary filtrate is produced in the Bowman’s Capsule?

Answer 18

100%

Question 19

How much of filtrate is reabsorbed in the PCT?

Answer 19

80%

Question 20

How much of filtrate is reabsorbed in the Loop of Henle?

Answer 20

6%

Question 21

How much of filtrate is reabsorbed in the DCT?

Answer 21

9%

Question 22

How much of filtrate is reabsorbed in the Collecting Tubule?

Answer 22

4%

Question 23

For every 100ml of blood that is filtered, how much urine is created?

Answer 23

1ml of urine

Question 24

What are the three components of the Juxtaglomerular Apparatus?

Answer 24

1. Macula Densa
2. Juxtaglomerular Cells
3. Extraglomerular Mesanginal Cells

Question 25

Where is the Juxtaglomerular Apparatus located?

Answer 25

Vascular Pole of the Renal Corpuscle.

Question 26

Where are the Macula Densa cells located? What other structure do they touch?

Answer 26

- Ascending Limb of the Loop of Henle - Juxtaglomerular cells of the afferent arteriole

Question 27

What do the Macula Densa cells do?

Answer 27

1. Monitor Osmolality and fluid volume of DCT 2. Transmit signals to JG cells.

Question 28

Where are our juxtaglomerular cells located? What type of cell are they? What do they do in response to stimuli?

Answer 28

- Afferent arteriole of the renal corpuscle. - Modified smooth muscle cell - Synthesize Renin

Question 29

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?

Answer 29

1. NaHCO₃ 2. NaCl

Question 30

What is the mechanism of action of Carbonic Anhydrase Inhibitors?

Answer 30

Blocking reabsorption of NaHCO₃ in the PCT.

Question 31

How does caffeine affect urine output?

Answer 31

1. Caffeine weakly blocks adenosine receptors in PCT 2. Blocked adenosine receptors = ↑ UO

Question 32

What does adenosine binding to receptors in the PCT do?

Answer 32

Adenosine binding in the PCT will ↓ UO. (Because adenosine presence means we need to conserve energy, creating urine is energy intensive.)

Question 33

Which transporter(s) starts the cycle in the PCT to preserve HCO₃⁻ ? How does it start the above stated cycle?

Answer 33

NHE3 Apical Surface Transporter NHE3 exchanges Na⁺ for H⁺

Question 34

In the HCO₃⁻ Retention cycle of the PCT, what occurs to the H⁺ once its placed into the urine by the NHE3 transporter?

Answer 34

H⁺ binds to HCO₃⁻ forming H₂CO₃

Question 35

What enzyme cleaves H₂CO₃ into CO₂ + O₂ ? What occurs if this enzyme is inhibited?

Answer 35

CA (Carbonic Anhydrase) * HCO₃⁻ is lost to the urine * NHE3 affected = Na⁺ loss

Question 36

What is the only CA Inhibitor still in use?

Answer 36

Acetazolamide

Question 37

What are Acetazolamides effects on: 1. NaCl 2. NaHCO₃ 3. K⁺ 4. pH

Answer 37

1. ↓ serum NaCl 2. ↓↓↓ NaHCO₃ 3. ↓ K⁺ 4. Metabolic Acidosis ( HCO₃⁻ loss )

Question 38

What is normal serum osmolality? What is the osmalality in the deepest parts of the renal medulla?

Answer 38

300 mOsm/kg 1200 mOsm/kg

Question 39

What is the osmolality of the renal cortex?

Answer 39

Variable: 100-300 mOsm/kg

Question 40

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?

Answer 40

Mannitol Mannitol does **not** get reabsorbed.

Question 41

What does the S2 segment of the PCT have in comparison to other parts of the nephron?

Answer 41

Protein Transporters

Question 42

What occurs in the descending limb of the Loop of Henle? What characteristic does the tissue have that makes this occur here?

Answer 42

H₂O reabsorption Hypertonic medullary interstitium

Question 43

Which portion of the Loop of Henle is impermeable to H₂O ?

Answer 43

Thick Ascending Limb (TIL)

Question 44

How are Mg⁺⁺ and Ca⁺⁺ reabsorbed in the Thick Ascending Limb?

Answer 44

1. K⁺ is moved from ICF to urine. 2. K⁺ excess makes urine + charged. 3. Positively (+) charged urine drives Mg⁺⁺ and Ca⁺⁺ through pericellular route to blood interstitium.

Question 45

Would the loop of Henle have a relatively low or high osmolality?

Answer 45

↑ Osmolality

Question 46

Which transporter moves NaCl and K⁺ into the ICF of the Thick Ascending Limb?

Answer 46

NKCC2

Question 47

Which diuretic class inhibits NaCl reabsorption in the Thick Ascending Limb (TAL) ? Which transporter is blocked to achieve this effect?

Answer 47

Loop Diuretics (Furosemide) NKCC2

Question 48

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?

Answer 48

Loop Diuretics (Furosemide, etc.) Ethacrynic Acid (Loop diuretic w/ no sulfa)

Question 49

Which diuretic class is useful as it is the most efficacious class and also does not cause metabolic acidosis?

Answer 49

Loop Diuretics

Question 50

How does furosemide increase secretion (loss through urine) of Mg⁺⁺ and Ca⁺⁺ ?

Answer 50

1. ↓ NaCl reabsorption 2. K⁺ ICF concentration ↓ 3. Urine + decreases 4. No + urine = ↓ movement of Mg⁺⁺ and Ca⁺⁺

Question 51

What type of bodily pH might result from Loop diuretic administration? Is there HCO₃⁻ loss from this drug class?

Answer 51

Slight Alkalosis No HCO₃⁻ loss