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26 terms

Toxic Chemicals

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Poison
A substance that in relatively small doses produce serious illness or death
toxin
poisonous substance secreted by animals and plants
include venom
toxicant
any substance that produces toxicity following exposure. often associated with human made substances
xenobiotic
any substance that is foreign to the body
Paracelsus
therapeutic use of chemicals and minerals in medicine
"the right dose differentiates a poison from a remedy
descriptive toxicologist
conduct studies, in lab animals to assess the relative toxicity of chemicals of interest
mechanistic toxicologist
conducts experiments to understand how a chemical functions at the organismal/cellular/biochemical/molecular levels to perturb normal biochemistry and physiology
regulatory toxicologist
evaluate toxicological and epidemiological data to establish standars for the protection of huma health
acute exposure
single dose of a toxicant for less than 24 hours
subacute exposure
repeated dose of the toxicant for one month or less
sub-chronic exposure
repeated doses over a time period of typically one-3 months
chronic exposure
repeated, prolonged exposure
bioavailability
the proportion of dose that is available biologically and which reaches the systemic circulation
individual/graded dose response curve
dose related increase in the severity of the response
usually a measurable threshold for an effect
quantal dose response relationship
describe dose response relationships that are all or none (typically determination of a median lethal dose)
selective toxicity
chemical produces injury to one species or one type of organism without harming another
additive toxicity
the toxicity of the mixture is the sum of the individual toxic responses (pesticides)
potentiative
(2+0=4) two compounds have different toxic potencies where only one is toxic
synergistic
2+2=8 two chemicals are both toxic, but co-exposure cause a greater response together than the sum of the individual responses
antagonistic
2+2=1 one compound negates of toxicity of another
ADME
disposition of toxic compound in a biological syste
passive diffusion
most important mechanism for absorption for toxic compounds.
concentration gradient
lipid soluble
non-ionized
filtration through pores
translocation of chemicals through membranes by means other than passive diffusion, important only for small chemicals
active transport
translocation of chemicals through membrane that requires energy and specific membrane carrier. goes against concentration
facilitated diffusion
translocation of chemicals through membrane that binds to carrier. does not require energy but requires membrane carrier and a concentration gradient
pinocytosis
translocation of chemicals through membrane through fluid membrane forms a vesicle/droplet