Principles Of Toxicology (Chapter 2 EOT) Flashcards
(61 cards)
The study of adverse effects of chemical, biological, or physical agents on living organisms and the environment
Toxicology
Foreign or synthetic substances with different intended purposes that are harmful are called ? or ?.
Xenobiotics or toxicants
Naturally occurring harmful substances that originate from plants, microbial organisms, or venoms are called ?
Toxins
Dose of chemicals needed to produce death in 50% of treated animals
LD50
Limitations of using the LD50 include:
Doesn’t reflect full spectrum of toxicity (carcinogens, teratogens, neurobehavior effects); doesn’t take into account individual variability which makes increases susceptibility to a toxin
Type of toxicologist that identifies cellular, biochemical, and molecular mechanisms by which chemicals exert toxic effects on living organisms
Mechanistic toxicologist
Hypersensitivity or allergic reactions require what in order to occur?
Prior exposure to the same or structurally similar chemical
The abnormal reactivity of an individual to a chemical based on their genetics or other individual sensitivity factors
Chemical idiosyncrasy
Idiosyncratic Drug reactions involve a combination of individual differences in the ability to:
1)form a reactive intermediate usually through oxidation to an electrophilic intermediate
2) detoxify the reactive intermediate through hydrolysis or conjugation
3) mount an immune response through human leukocyte antigens (HLAs) and T cells
4) cause cell death
What factors beyond genetics can cause idiosyncratic reactions?
Inflammatory stress, infection, mitochondrial dysfunction, environmental factors
What organ systems are most likely to be affected by idiosyncratic reactions?
Skin, Liver, hematopoietic and immune systems
The likelihood of a toxic response to be reversed largely depends on ?
The ability of the injured tissue to adapt, repair and regenerate
The target organ of toxicity and the site of the highest concentration of the exposed chemical are almost always the same.
False
This type of effect occurs when the combined responses of two chemicals are equal to the sum of the responses to each chemical given alone
Additive effect (2+3=5)
Type of effect when the combined responses of two chemicals are much greater than the sum of the response to each chemical when given alone
Synergistic effect (2+2=20)
Occurs when one substance does not produce any toxicity on a particular tissue or system, but when added to another chemical makes that chemical much more toxic
Potentiation (0 + 2 =10)
Occurs when two chemicals administered together interfere with each other’s actions or one interferes with the action of another
Antagonism (4+6= 8), (4+ (-4)= 0), (4+0=1)
Four types of antagonism are:
Receptor, chemical, dispositional, functional
Receptor antagonists are also known as
Blockers
Chemical antagonism is also known as
Inactivation
Chelation of metal ions is an example of what kind of antagonism
Chemical
Type of antagonism when the absorption, distribution, biotransformation, or excretion of a chemical is altered so the concentration or duration of chemical at target organ is reduced
Dispositional
Type of antagonism when 2 chemicals counterbalance each other by producing opposing effects on the same physiological function often by using different signaling pathways
Functional antagonism
This type of tolerance results from a lower availability of receptors and/or mediators (neurotransmitters)
Chemical or cellular tolerance
