Lecture 6

Question 1

Under what conditions is ANP released?

Answer 1

1) HTN
2) Severe increase in ECF volume (as in CHF)

Question 2

Where does ANP act?

Answer 2

Afferent arteriole and collecting duct

Question 3

How does ANP affect the afferent arteriole? the collecting duct?

Answer 3

Afferent arteriole = vasodilation (increased RBF/GFR)

Collecting duct = suppresses reabsorption of sodium

Question 4

How does ANP affect water and sodium excretion?

Answer 4

ANP increases water and sodium excretion to DECREASE pressure

-Na/Cl secreted into lumen
-Water remains in lumen

Question 5

How does ANP affect aldosterone and renin secretion?

Answer 5

Inhibits renin and aldosterone secretion

Question 6

What is the most common cause of renal failure?

Answer 6

HTN and Diabetes

Question 7

How do diabetes and hypertension affect the hydrostatic glomerular capillary pressure? Clinical effect?

Answer 7

Diabetes and HTN increased hydrostatic glomerular pressure, leading to glomerularsclerosis

Question 8

What effect does Angiotensin Type I receptor have on vessels? Kidney?

Answer 8

Vessels: vasoconstriction
Kidney: increase Na reabsorption, vasoconstriction, aldosterone secretion

Question 9

How does inhibiting Ang II (AT1 Antagonists or ACE Inhibitors) affect efferent arteriole and tubule scarring?

Answer 9

1) Vasodilation of efferent arterioles
2) Decreases proteinuria and inflammatory cytokines = tubular scarring

Question 10

High blood sugar
leads to an increase in a unique Na-Glucose
co-transporter in the proximal tubule, which is known as ____

Answer 10

SGLT2

Question 11

How does SGLT2 affect the afferent and efferent arteriole?

Answer 11

Afferent = vasodilates
Efferent = vasoconstricts

-Increases GFR and Pgc

Question 12

True or False: High glomerular pressures caused by SGLT2 leads to hypo-filtration and glomerulosclerosis

Answer 12

False - High glomerular pressures caused by SGLT2 leads to hyper-filtration and glomerulosclerosis

Question 13

In diabetic patients, RAAS inhibition reduces blood pressure and causes the efferent
arteriole to dilate. But there is a problem. What is it?

Answer 13

SGLT2 induced dilation of the afferent arteriole is
not corrected. Therefore, you have still have high RBF, GFR, and Pgc

Question 14

All diuretics work by inhibiting __ reabsorption

Answer 14

Na

Question 15

____: Increase the excretion of Na (Natriuresis) and water

Answer 15

Diuretics

Question 16

How does inhibition of Na reabsorption via diuretics affect loss of filtered water and ECF volume?

Answer 16

Leads to loss of filtered water and reduces
extracellular fluid volume

Question 17

How are diuretics self-limiting?

Answer 17

Reduced volume means reduced BP. Therefore: RAAS is stimulated and there is more sodium reabsorbed in areas of nephron not affect by diuretic.

Question 18

True or False: The net effect of diuretics is a limited reduction in ECF volume

Answer 18

True

Question 19

_____: Un-reabsorbable solutes

Answer 19

Osmotic diuretics

Question 20

Mannitol is an example of what type of diuretic?

Answer 20

Osmotic diuretic

Question 21

Where does mannitol function?

Answer 21

Proximal tubule

Question 22

How does mannitol affect water reabsorption in the proximal tubule?

Answer 22

Slows and decreases H2O reabsorption
- As a consequence, ions (mostly sodium) reabsorption is also limited

Question 23

What type of diuretic is Glucose?

Answer 23

Osmotic diuretic
-when the filtered load exceeds the capacity
of glucose co-transporters (Tm)

Question 24

True or False: Osmotic diuretics (e.g glucose, mannitol) are used in cases of acute fluid overload, not to control
arterial hypertension.

Answer 24

True

Question 25

Answer 25

Question 26

Acetazolamide is an inhibitor of the enzyme
______

Answer 26

carbonic anhydrase (CA)

Question 27

Inhibition of carbonic anhydrase using acetazolamide will affect which transporter and have what effect?

Answer 27

Slows Na-H exchanged on apical membrane of proximal tubule

• Water excretion

Question 28

What is the role of the Na-H in the proximal tubule?

Answer 28

Na+ reabsorption

Question 29

How do CA Inhibitors like acetazolamide affect H+ excretion?

Answer 29

Reduce H+ excretion and bicarb recovery
- Metabolic acidosis

Question 30

Loop Diuretics such as Furosemide (Lasix) are used to treat what two conditions?

Answer 30

Acute pulmonary edema and congestive heart failure.

Question 31

How do Loop Diuretics work?

Answer 31

Blocking the Na/K/2Cl- Co-transporter in thick ascending loop
- this transporter is important for making salty medulla
- salty medulla is needed for water reabsorption

Question 32

Where do Thiazide Diuretics work? What transporter do they affect? Overall effect?

Answer 32

-Distal Convoluted Tubule
-Block Na/Cl co-transporter
-Net sodium and water loss

Question 33

Inhibition of the Na/Cl co-transporter via Thiazide diuretics will shift some of the re-absorption of
Na+ to which co-transporter?

Result?

Answer 33

Na/Ca2+

Thiazide diuretics promote calcium reabsorption

Question 34

Which diuretic can be used to lower blood pressure and treat kidney stones resulting from elevated Ca2+ in the urine?

Answer 34

Thiazide diuretics

Question 35

Which diuretics promotes bone mineral formation?

Answer 35

Thiazide diuretics

Question 36

For thiazide diuretics, as Na+ travels down the collecting duct, it will activate the ___ in
the principal cells to increase Na re-absorption. This results in ___ loss.

Answer 36

Na/K pump; K+ loss

Question 37

Principal cells are the site of action for two different diuretics: ___ and ___

Answer 37

Amiloride and Spironolactone

Question 38

Which diuretic inhibits sodium channels (ENaC), which prevents Na re-absorption and leads to water excretion?

Answer 38

Amiloride

Question 39

Which diuretic block aldosterone receptors (Na/K Pump), leading to Na and water loss?

Answer 39

Spironolactone

Question 40

What are the two K sparing diuretics?

Answer 40

Amiloride and spirolactone

Question 41

True or False: Inhibiting Na-reabsorption in the collecting duct (blocking ENaC - amiloride) (blocking the Na/K exchanger - spironolactone) prevents the loss of K+

Answer 41

True

Question 42

The use of Osmotic, Loop, and Thiazide diuretics all leads to…?

Answer 42

Greater delivery of Na and water to the collecting duct and principal cells

-Stimulates: Na re-absorption and K+ excretion
-Thus: these are K-losing diuretics