Excretion

Question 1

3 primary types of excretion

Answer 1

Renal, Biliary, pulmonary

Question 2

3 processes involved in changing blood level of a xenobiotic

Answer 2

Glomerular filtration,
Tubular reabsorption
Tubular secretion
ie. nephron

Question 3

What is the route for the nephron tubules

Answer 3

Glomerulus, proximal convoluted tubule, Henle loop, Distal convoluted tubule, cortical collecting duct
( has a huge concentration gradient )

Question 4

enzymes/cells in kidney tubules

Answer 4

Oat1, Oct1, 2, Octn1,2, Oat 4c1, Mrp2, Mrp4, Bcrp, Mdr1a, Mdr1b

Question 5

Extrarenal excretion

Answer 5

1. Biliary excretion
   - important for “larger” xenobiotic molecules (MW > 300 g/mol)
   OAT OCT MDR MRP BCRP

Question 6

cont.

Answer 6

2. pulmonary excretion (exhalation) breathalyzer
3. Lactation - important consideration for neonatal exposure and food products ie milk and cheese

Question 7

Enterohepatic Cycling

Answer 7

xenobiotic metabolites excreted in the bile into the intestine can be reabsorbed and distributed back to the liver, exacerbate toxicity to the liver

Question 8

What are three minor routes of excretion

Answer 8

saliva
sweat
hair, nails

Question 9

Summation (additivity)

Answer 9

This is the most common 2+2=4

Question 10

Synergism

Answer 10

the effects of 2 xenobiotics in combination exceeds the sum of their individual effects (2+2 = 10)

Question 11

Potentiation

Answer 11

a xenobiotic with no effect intensifies (potentiates) the effects of a second xenobiotic (2+0=10)

Question 12

Antagonism

Answer 12

the effect of 2 xenobiotic in combination is less than additive (2+2 =1 )