Principles of Toxicology

Question 1

What is toxicology?

Answer 1

the study of adverse effects of chemicals on living systems

Question 2

What is toxicity?

Answer 2

the capacity of a substance to produce injury under defined conditions of route, dose, and duration of exposure

Question 3

What is toxicokinetics?

Answer 3

rates of absorption, distribution, excretion, and metabolism of toxicants

Question 4

What is organ toxicity?

Answer 4

alternation in cell structure or function

Question 5

What is carcinogenesis?

Answer 5

derangement of cell reproduction and growth of cells

Question 6

What is mutagenesis?

Answer 6

formation of changes in genetic material

Question 7

Teratogenesis?

Answer 7

toxicant-induced formation of birth defects

Question 8

Reproductive toxicity?

Answer 8

effects on fertility, rates of conception and embryonic or fetal toxicity

Question 9

What is volume of distribution equal to?

Answer 9

Dose/plasma concentration. small Vd is remains in blood, high Vd if enters tissue

Question 10

What is clearance?

Answer 10

Urine concentration * Rate /

Plasma concentration

Question 11

What is total clearance?

Answer 11

hepatic clearance + pulmonary clearance + kidney clearance…

Question 12

What is exposure a function of?

Answer 12

concentration of toxicant and length/time of the exposure

Question 13

Define the following type of exposures: acute, subacute, subchronic, and chronic.

Answer 13

acute - singe exposure, then chemical removed

subacute: exposure up to 1 month
subchronic: 1-3 months
chronic: long term (2 years in a rodent)

Question 14

What is a hypersusceptible dose response?

Answer 14

individual that responds to very low doses of a toxicant. Shift to the left of dose response curve.

Question 15

What is a resistant dose response?

Answer 15

individual responds to only very high doses of drug. Shift to right of dose response curve

Question 16

What is potency?

Answer 16

mg/kg necessary for an effect to occur

Question 17

What is effectiveness?

Answer 17

Maximal effect tissues can produce

Question 18

What is hormesis?

Answer 18

Dose range with very desirable effect but too little does not protect body or too much has very deleterious effects. This occurs with vitamins.

Question 19

What is an additive chemical reaction?

Answer 19

2+3 = 5

Question 20

What is a synergistic chemical reaction?

Answer 20

2+3 = 20, ex) alcohol and tylenol

Question 21

What is potentiation in a chemical reaction?

Answer 21

0 + 3 = 20. Ex) carbidopa/levodopa

Question 22

What are different types of antagonistic chemical reactions?

Answer 22

Functional - sympathetic & parasympathetic; Chemical - chelation;
Dispositional - alter uptake, protein binding, excretion;
Receptor- agonist + antagonist

Question 23

What are the factors affecting toxic responses?

Answer 23

SHADED: Sex (pregnancy, hormones); Host factors; Age; Diet; Environment; Diseases of liver and kidney (metabolism & excretion)

Question 24

What is risk vs. safety?

Answer 24

Risk is the probability that a substance will produce harm under specified conditions and safety is that probability that harm will not occur

Question 25

What are risk assessment considerations?

Answer 25

1. Identification of hazardous chemical
2. Animal data
3. invitro experiments
4. Clinical or epidemiological data
5. Political consequences of chemical use/regulation
6. Public perception of risk