Renal Elimination Materials (W3)

Question 1

Glomerular Filtration

Answer 1

• Glomerulus
• About 100 for W and 120 for M
• (blood TO nephron)
• WITH conc. gradient
• Eq: Fu * GFR

Question 2

Active Secretion

Answer 2

• Proximal Tubule
• (blood TO nephron)
• Can go against conc. gradient, needs energy, saturable

Question 3

Reabsorption

Answer 3

• Distal Tubule
• (nephron TO blood)
• Diffuse through cell membrane back into blood
• UNIONIZED and LIPOPHILIC drugs

Question 4

WEAK BASE

Answer 4

• As urine pH increases, it will be more unionized
• Causing MORE reabsorption
• So, CL(R) will decrease
• pKa < 6, completely unionized (freely diffuses)
• pKa > 12, completely ionized (no reabsorption)

Question 5

WEAK ACID

Answer 5

• As urine pH increases, it will be more ionized
• Causing LESS reabsorption
• CL(R) will increase
• pKa < 3, completely ionized (no reabsorption)
• pKa > 7.5, completely unionized (freely diffuses)

Question 6

Conceptually…

Answer 6

CL(R) = + GFR + AS - Reabs.

• If CL(R) > fu * GFR = likely net active secretion
• If CL(R) < fu * GFR = likely net reabsorption