lecture 24

Question 1

Define toxicology.

Answer 1

the study of adverse effects of chemical or physical agents on living systems

Question 2

Provided a substance, determine if it is properly denoted as a toxin or a toxicant.

Answer 2

toxin: a poisonous substance produced by living cells (venoms, mycotoxins, microbial toxins)

toxicant: a man-made chemical introduced into the environment that produces toxic effects on living cells (ethylene glycol, carbon tetrachloride)

Question 3

Provided a specific activity/intervention, indicate whether the activity/intervention is an example of descriptive, mechanistic, or regulatory toxicology.

Answer 3

descriptive: identify phenotypic changes resulting from exposure to toxic substances (is it toxic? do people have adverse effects?)

mechanistic: identify how toxic substances alter normal cellular function (why is it toxic? perform analysis, how it is metabolized, etc.)

regulatory: assess the safety of exposure levels of toxic substances (what should we do about it? action typically taken by regulatory agencies)

Question 4

Differentiate between local versus systemic, immediate versus delayed, and reversible versus irreversible toxic responses.

Answer 4

local: effect observed at site of contact or portal of entry
systemic: effect observed at site distant from contact or portal of entry

immediate: seconds to hours
delayed: days to years

reversible: effect abates after stopping exposure
irreversible: effect persists after stopping exposure

Question 5

Given a case of a toxic exposure, determine which of the three phases of toxic responses are ongoing.

Answer 5

exposure: source, environmental fate, ingestion, inhalation, dermal absorption

disposition: where the toxin/toxicant goes once exposed (ingested to GI tract, inhaled to lungs, dermal to blood; and where it goes after that, how it is excreted; basically ADME)

toxicodynamics: cellular responses

Question 6

Given a case of toxic exposure, identify three means by which toxic responses may be mitigated.