Exam 3: Lecture 9, Intro to Toxicology Flashcards
Important concept of Toxicology?
Dose makes the poison
Toxicology definition?
study of adverse effects of chemical, biological or physical agents on living organisms and the environment
Tox substances:
Toxins = naturally occurring
Toxicants = synthetic chemicals with different intended purposes
Hazard is
ability of substance to cause damage, inherent propery
Risk is…
chance/probability of toxicity from exposure
risk assessment - estimate potential effect on human health
LD50
Lethal dose, at which half subjects die
the Higher it is, the less toxic something is
Idosyncratic reactions are…
abnormal reactivity of an individual to a chemical based on its genetic, or other individual sensitivity factors with relatively low incidence
can occur in any organ system, skin/liver/hematopoeitic/immune system must affected
Reversible Toxicity
largely depends on ability of an injured tissue to adapt, repair and regenerate
Live and GI have high ability to regenerate
Irreversible Toxicitiy
CNS has much more limited ability to divide and replace damage neurons
cancers and birth defects cause by chemical exposures
Local Toxicity
occur when contact is 1st made by toxicant and the biological system
produced by ingestion of toxic substances or inhalation of irritant materials
Systemic Toxicity
require absorption and distribution of toxicant from its entry point to a distance site where the deleterious effects are produced
most substances produce systemic effects except highly reactive
Most chemicals usually elicit major toxicity in…
only 1 or 2 organs and not all organs
not always site of highest conc
target organs of toxicity
Additive effect
combined responses of two chemicals is equal to cub of responses to each chemical given alone
Synergistic effect
combined responses of two chemicals are much greater than the sum of the responses to each chemical given alone
Potentiation
one substance does not produce any toxicity on a particular tissue or system but when added to another chemical makes that chemical more toxic
Antagonism
Two chemicals administered together interfere with each others actions or one interferes with the action of the other
Receptor antagonism
two chemicals bind to same receptor produce less of an effect when given together relative to the addition of their separate effects
Chemical antagonism or inactivation
direct chemical interaction between 2 compounds that produce a less toxic effect
Dispositional antagonism
disposition is altered such that the conc and or duration of chemical at target organ is reduced
Functional antagonism
2 chemicals counter balance each other by producing opposing effects on the same physiological function
Tolerance
repeated exposure to a chemical can reduce its pharmacological and/or toxicologic response
Dispositional tolerance
amount of chemical reaching site of action decreases over time
Chemical or cellular tolerance
lower availability of receptors and/or mediators
Species Differences
different doses can cause different effects in different species