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Diuretics Flashcards

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1
Q

What is the primary function of diuretics?

A

Lowering blood pressure and reducing excess fluid buildup

Diuretics increase urinary volume and are useful in conditions like heart failure.

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2
Q

Define diuretic.

A

Something that increases urinary volume

Caffeine can also be considered a diuretic.

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3
Q

What differentiates a diuretic from a natriuretic?

A

Diuretics increase urinary volume; natriuretics increase sodium ion secretion

Most diuretics are natriuretics, but not all.

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4
Q

Name the three principal activities of the nephron.

A
  • Filtration
  • Reabsorption
  • Secretion

These activities are essential for urine formation.

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5
Q

Where does filtration occur in the nephron?

A

At the glomerulus

The glomerulus is a capillary network where blood filtration begins.

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6
Q

What is the role of the Bowman’s capsule?

A

Surrounds the glomerulus and collects filtrate

It is part of the nephron.

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7
Q

What are the two main types of diuretics?

A
  • Loop diuretics
  • Thiazides

Loop diuretics include furosemide (Lasix) and ethacrynic acid.

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8
Q

What is the function of the macula densa?

A

Senses fluid and osmolality in the distal convoluted tubule

It plays a role in regulating blood pressure and fluid balance.

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9
Q

True or false: Mannitol is a natriuretic agent.

A

FALSE

Mannitol is a diuretic but not necessarily a natriuretic.

Mannitol adjust osmolality of proximal tubule to around 600 instead of 300 which pulls water into the tubules increasing urine output

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10
Q

What is the collecting duct?

A

The last part of the nephron where urine is collected

  • utilizing ADH to bind to V2 which moves vesicles to cell membrane activating aquaporins which pulls water into the tubules making less urine

It receives fluid from multiple nephrons.

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11
Q

What is the function of the juxtaglomerular apparatus (JGA)?

A

Regulates blood pressure and filtration rate

It includes the macula densa and juxtaglomerular cells.

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12
Q

Fill in the blank: The loop of Henle is further subdivided into the _______ and _______ limbs.

A

descending limb and ascending limb

These limbs have different permeabilities and functions.

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13
Q

What percentage of filtrate is typically reabsorbed in the proximal convoluted tubule?

A

80%

This is a significant reabsorption site in the nephron.

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14
Q

What is the primary role of SGLT2 inhibitors?

A

Increase glucose secretion into urine and lower blood pressure

They are primarily anti-diabetic medications.

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15
Q

What is the renal cortex?

A

The outer surface of the kidney containing glomeruli and tubules

The cortex is distinct from the medulla, which is more internal.

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16
Q

What is the renal medulla?

A

The inner part of the kidney where the loop of Henle and collecting ducts are located

It does not contain glomeruli.

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17
Q

What is the role of the glomerulus in the kidney?

A

Filters blood to create glomerular filtrate

The glomerulus has a higher pressure differential due to the size difference between the afferent and efferent arterioles.

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18
Q

What does the macula densa sense in the kidney?

A

Osmolality and flow

  • High/low pressure
  • High/low flow
  • High/low sodium delivery

It transmits information to the afferent arteriole to regulate blood flow and pressure.

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19
Q

What happens when the pressure is too high in the kidney?

A

Sensed by macula densa
Signals sent to JG cells located on Afferent arterioles
* Afferent arteriole shrinks
* Nitric oxide production stops

This reduces blood flow and decreases glomerular filtration rate.

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20
Q

What is secreted by the juxtaglomerular cells when pressure is too low?

A

Renin

This activates the renin-angiotensin-aldosterone system to increase blood pressure.

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21
Q

What are the three types of regulation for blood pressure via glomerular filtration rate?

A
  • Renal regulation- macula densa, JG cells, renin (RAAS)
  • Neural regulation - cns (sympathetic / parasympathetic )
  • Hormonal regulation (ADH)

These mechanisms help maintain homeostasis and regulate blood pressure.

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22
Q

What is the function of the proximal convoluted tubule?

A

Selective reabsorption of substances

It reabsorbs sodium, bicarbonate, glucose, amino acids, and water.

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23
Q

What do carbonic anhydrase inhibitors do?

A

Block sodium bicarbonate absorption

This leads to increased sodium and bicarbonate in urine, affecting blood pH.

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24
Q

What is the effect of mannitol as a diuretic?

A

Increases osmotic pressure in the tubule

It prevents water reabsorption by keeping osmolality high.

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25
What occurs in the **descending loop of Henle**?
Water reabsorption due to permeability ## Footnote The hypertonic medullary interstitium draws water out.
26
What is the **sodium-potassium-2-chloride transporter (NKCC2)** responsible for?
Transporting sodium, potassium, and chloride into the cell ## Footnote This occurs in the ascending loop of Henle, which is impermeable to water.
27
Fill in the blank: The **juxtaglomerular apparatus** regulates glomerular filtration rate by adjusting the diameter of the _______.
afferent arteriole ## Footnote This adjustment helps control blood flow and pressure into the glomerulus.
28
What is the **sodium, potassium, 2-chloride transporter known as?
NKCC2 ## Footnote helps balance osmotic gradients by transporting ions into the cell at ascending loop of henle.
29
In the nephron, the **descending limb** is characterized by what property?
Freely water-supermeable ## Footnote This allows water to move out of the nephron, changing osmolality.
30
What happens in the **ascending loop** of the nephron?
Water impermeable, sodium, potassium, and chloride are transported into the cell ## Footnote This helps to balance osmolality on either side.
31
What are the effects of **loop diuretics**?
Block NKCC2 * Inhibit sodium chloride reabsorption * Increase fluid loss * Potentially cause alkalosis ## Footnote Examples include furosemide and bumetanide. Watch for sulfa allergies
32
What is a significant side effect of **potassium-wasting diuretics**?
Loss of potassium ## Footnote This can lead to electrolyte imbalances and requires monitoring.
33
What is the role of **aldosterone** in the collecting tubule?
* Increases sodium absorption ; water follows = decrease urination * Increases potassium secretion ## Footnote Aldosterone is part of the renin-angiotensin-aldosterone system. Activates ENAC transporter in collecting tubules
34
What is the function of the **ENAC transporter**?
Epithelial Na channel Passive Sodium transport in the collecting tubule ## Footnote It is influenced by aldosterone and affects potassium levels.
35
What do **potassium-sparing diuretics** do?
* Antagonize aldosterone * Reduce sodium reabsorption * Decrease potassium loss ## Footnote Examples include spironolactone and amiloride.
36
What is the consequence of **hyperkalemia**?
Increased potassium levels in the blood ## Footnote This can lead to arrhythmias and potentially be fatal.
37
What is the effect of **thiazide diuretics** on calcium?
Active calcium reabsorption ## Footnote Thiazides can also cause some bicarbonate loss. 1. Primary effect: Thiazides inhibit the Na⁺/Cl⁻ cotransporter (NCC) on the luminal (apical) membrane. → This reduces sodium entry into the DCT cells. 2. Secondary effect on calcium: • Because less sodium enters the cell, the intracellular Na⁺ concentration falls. • enhances the activity of the basolateral Na⁺/Ca²⁺ exchanger (NCX1), which pumps Na⁺ in and Ca²⁺ out of the cell (into the blood). • The increased Ca²⁺ efflux into the blood lowers intracellular Ca²⁺, which promotes more calcium entry from the tubular lumen through apical Ca²⁺ channels (TRPV5). ➜ Net effect: More calcium reabsorption → less calcium excreted in urine.
38
The **collecting tubule** is influenced by which hormones?
* Aldosterone * Parathyroid hormone ## Footnote These hormones help regulate sodium and calcium levels.
39
What is the primary role of **carbonic anhydrase inhibitors**?
Inhibit bicarbonate reabsorption Block na and bicarb Ex: acetazolamide ## Footnote This can lead to metabolic acidosis.
40
What is the **osmolality** in the proximal distal tubule compared to the cortex?
About 300 ## Footnote This maintains balance in the nephron.
41
What happens to potassium levels when sodium increases in the collecting tubule?
More potassium is secreted ## Footnote This is due to the positive charge balance between sodium and potassium.
42
What is the **mechanism** for potassium loss in potassium-wasting diuretics?
This is due to the negative lumen potential. K wasting diuretics cause a net charge difference. Increased sodium influx leads to increased potassium efflux ## Footnote Can also block sodium bicarbonate which makes urine more negative making K want to leave more
43
True or false: **Loop diuretics** cause acidosis.
FALSE ## Footnote Loop diuretics may cause slight alkalosis instead.
44
What can happen if excess potassium is not excreted from the body?
* Hyperkalemia * Arrhythmias * Fatal outcomes ## Footnote Both hypo- and hyperkalemia can lead to serious heart rhythm issues.
45
What are **potassium-sparing diuretics** primarily used for?
* Conn's syndrome * Excess aldosterone production * Ectopic corticotropic hormone production ## Footnote These diuretics antagonize the effects of aldosterone.
46
What is **Conn's syndrome** characterized by?
Excess production of aldosterone ## Footnote It is a condition that can lead to hypertension and hypokalemia.
47
True or false: **Potassium-sparing diuretics** are FDA-approved for use in congestive heart failure (CHF).
FALSE ## Footnote Many potassium-sparing diuretics are used off-label for CHF.
48
What are the contraindications for using potassium-sparing diuretics?
* Potassium supplements * Liver disease * Renal disease ## Footnote These conditions can exacerbate hyperkalemia.
49
What hormone is produced in the **pituitary gland** that increases water reabsorption?
Antidiuretic hormone (ADH) ## Footnote ADH is also known as vasopressin.
50
What effect does **antidiuretic hormone** have on urine concentration?
* Increases water reabsorption * Makes urine more concentrated ## Footnote ADH acts on the collecting duct to enhance water retention.
51
What is the primary osmotic diuretic used for reducing **intracranial pressure**?
Mannitol ## Footnote Mannitol is a carbohydrate alcohol that is not absorbed in the intestines.
52
What is a potential toxicity of **mannitol** when used as a diuretic?
* Extracellular volume expansion * Hypernatremia * Dehydration ## Footnote Mannitol can cause excessive water displacement initially before diuresis occurs. Usually in first 30-60 min
53
Fill in the blank: The **proximal convoluted tubule** reabsorbs approximately _______ of the glomerular filtrate.
80% ## Footnote This area is crucial for reabsorbing water and solutes.
54
What happens to urine osmolality when **antidiuretic hormone** is absent?
Urine becomes very dilute ## Footnote Without ADH, water reabsorption is significantly reduced.
55
What is the role of **aquaporins** in the nephron?
Facilitate water reabsorption ## Footnote Aquaporins are water channels that increase permeability in the collecting duct.
56
What is the effect of **vasopressin** on blood pressure?
Can increase blood pressure ## Footnote Vasopressin is not the primary method for rapid blood pressure increase. Binds to gpcr V2 receptor blocking increasing camp allowing aquaporins to be opened allowing water reabsorption into collecting duct. Will have concentrated urine
57
What is the primary action of **osmotic diuretics** in the nephron?
Increase urine output by raising osmolality -goes up to about 600 mosm from 300 mosm ## Footnote Water gets pulled into tubule due to creating a high osmotic gradient =increases urine Primarily works at proximal tubule
58
What is the primary function of the **proximal convoluted tubule**?
* Reabsorb most substances pushed out in the glomerulus * High water permeability * Target for carbonic anhydrase enzyme ## Footnote Mannitol primarily functions in the proximal convoluted tubule.
59
Which transporter do **loop diuretics** target?
NKCC2 transporter ## Footnote Furosemide is a common loop diuretic that targets this transporter.
60
What are the **most commonly prescribed diuretics** initially?
* Thiazides * Loop diuretics ## Footnote Thiazides are typically used unless the patient has a sulfur allergy.
61
In which part of the nephron do **potassium-sparing diuretics** work?
Cortical collecting tubule and collecting duct ## Footnote This is where aquaporins and ADH receptors are located.
62
True or false: Combining diuretics that work in the **same area** of the nephron is effective.
FALSE ## Footnote Combining diuretics in the same area does not significantly increase fluid movement.
63
List some **conditions** for which diuretics are indicated.
* Hypertension * Congestive heart failure * Kidney disease * Cirrhosis * Peripheral or pulmonary edema ## Footnote Diuretics help manage fluid retention in these conditions.
64
What is the difference between **neurogenic** and **nephrogenic** diabetes insipidus?
* Neurogenic: insufficient ADH production * Nephrogenic: kidneys do not respond to ADH ## Footnote Neurogenic is treated with vasopressin, while nephrogenic may require diuretics like thiazides to reset kidneys
65
What is the effect of **thiazide diuretics** on sodium reabsorption?
Block NCC (NaCl channel) Decreases distal tubule sodium reabsorption ## Footnote This leads to increased sodium and water excretion.
66
Fill in the blank: **Diuretics** are commonly used for managing __________.
hypertension ## Footnote They may be the first line of treatment for high blood pressure.
67
What are the **three main classes** of diuretics mentioned?
* Carbonic anhydrase inhibitors * Thiazide diuretics * Loop diuretics ## Footnote Additional classes include potassium-sparing diuretics and osmotic diuretics.
68
What is a potential side effect of combining **loop diuretics** and **thiazides**?
Loss of sodium and potassium ## Footnote This combination can lead to significant fluid movement.
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