RBF & GFR DSA

Question 1

What is the Tamm-Horsfall protein?

Answer 1

Protein that appears in urine but is not filtered from the glomerulus.

Instead it is secreted from into the nephron tubule lumen from the Thick Ascending Limb of the Loop of Henle

Tamm-Horsfall protein helps prevent Ca2+ crystallization (kidney stones)

Question 2

How small does a molecule have to be in order to be freely filtered?

Answer 2

Less than 20 angstroms

Question 3

How large does a molecule have to be in order to not be filtered?

Answer 3

More than 42 angstroms

Question 4

What is the average GFR?

Answer 4

125 ml/min

Question 5

What effect does an increase in filtration fraction have on oncotic pressure of the efferent arteriole?

Answer 5

Increased filtration fraction means more fluid is being filtered into the bowman’s space, leaving behind proteins.

With less fluid and more proteins, oncotic pressure increases.

Question 6

What are the 3 effects sympathetic stimulation has on the kidney?

Answer 6

Sympathetic stimulation will cause:

• Vasoconstriction (afferent arteriole more than efferent arteriole)
• Juxtaglomerular secretion of Renin
• Tubular Epithelial Cells activation of Na-K-ATPases, increasing Na+ reabsorption (in the PCT and DCT)

Question 7

What are the receptors require activation in order to carry out the 3 effects seen in sympathetic stimulation?

Answer 7

Vasoconstriction: Alpha-1 adrenergic receptor

Juxtaglomerular Renin Secretion: Beta-1 Adrenergic receptor

Na-K-ATPase activity: Alpha-1 Adrenergic receptor

Question 8

What effects does Angiotensin II have on kidney function?

Answer 8

• Exerts sensation of thirst
• Restores systemic blood flow via vasoconstriction
• Preferentially vasoconstricts the efferent arteriole

Question 9

What is the eventual goal of sympathetic innervation on kidney function?

Answer 9

Decreased urinary output
Increased Water intake
Decreased Na+ excretion

Question 10

What is a normal BUN:Creatinine ratio?

Answer 10

Between 10 and 20 to 1 (10-20:1)

Question 11

What BUN:Creatinine ratio would you see in a pre-renal problem?

Answer 11

Greater than 20:1

Question 12

What BUN:Creatinine ratio would you see in an intrarenal problem?

Answer 12

Less than 10:1

Question 13

What BUN:Creatinine ratio would you see in a post-renal problem?

Answer 13

Between 10 and 20 to 1 (10-20:1)

Question 14

What is PAH clearance used to estimate?

Answer 14

Renal Plasma Flow

Question 15

Clearance of what molecules can be used to estimate GFR?

Answer 15

Inulin and Creatinine