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30 Cards in this Set
- Front
- Back
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What is the definition of a xenobiotic?
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A general term referring to any chemical foreign to an organism
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What is the definition of toxic?
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Describes the effect of a toxicant
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What is the definition of toxicity?
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Describes the quantitative amount or dosage of a poison that will produce a defined effect
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What do you call the state of being poisoned by a toxicant?
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Toxicosis
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What is the definition of dosage?
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Correct terminology for toxicity expressed as amount of toxicant per unit of body weight
-Most accepted as mg/kg |
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What is the definition of hazard or risk?
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The probability that a toxicant will induce a disease state under the conditions of use or the likelihood of exposure to a particular toxicant under the conditions of use
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What are 3 common routes of exposure? Some less common routes?
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Common: inhalation, oral and dermal
Less common: intravenous, intramuscular, subcutaneous, sublingual and rectal |
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What is the threshold dose?
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The highest dose at which a significant effect could not be found
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What is the lethal concentration (LC)?
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The lowest concentration that causes death
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What is the acute lethal toxicity (LC50 or LD 50)?
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The dose at which 50% die
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What is the definition of absorption?
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The transfer of the xenobiotic from the site of exposure into the animal's biological system
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What is the definition of distribution?
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The movement of the xenobiotic to the site or sites of action
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What is the definition of metabolism?
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The pathway that a biological system follows in handling a xenobiotic
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Are highly ionized compounds usually more or less toxic, why?
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Less toxic because highly ionized compounds are poorly absorbed, non polar and lipid-soluble vehicles are more toxic
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How does protein binding affect the toxicity of a compound?
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Binding to serum albumin decreases bioavailability of agent thus reducing toxicity
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What are 2 vitamins that aid in scavenging of free radicals and repair of cellular protective mechanism?
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Vitamin C & vitamin E
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_______ represent a storage site for many xenobiotics and important physiologic constituents including steroid hormones, vitamins and various essential minerals.
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Plasma proteins
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Why are the liver and kidney ideal sites for postmortem sample collection?
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A variety of xenobiotics accumulate in liver and kidney
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What is the definition of biotransformation?
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Conversion of both endogenous and xenobiotic chemicals into water-soluble forms
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What is phase I of xenobiotic biotransformation?
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Generally involves oxidation, hydrolysis or reduction and convert apolar lipophilic xenobiotics into metabolites (hydroxyl, cytochrome p450)
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What happens during phase II of xenobiotic biotransformation?
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The xenobiotic or metabolites are conjugated with a functional group (e.g. glucuronide, sulfate, amino acids, glutathione, acyl or methyl groups)
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______ defines the presence of chemicals in different body compartments, such as plasma, extracellular fluids, intracellular fluids or total body water.
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Volume of distribution
-If storage occurs as shown for fat the volume of distribution may be overestimated |
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What is the definition of half life?
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A common expression for elimination of chemicals to one-half of the prior concentration with a specific time period
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______aspects of xenobiotic elimination can be used to determine the time frame and biological samples that are best suited for diagnosing a specific toxicosis.
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Toxicokinetic aspects
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What is the definition of toxicity?
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Describes the quantitative amount or dosage of a poison that will produce a defined effect
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What are the 3 phases of drug distribution?
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1) Mixing w/ blood
2) Distribution to tissues 3) Metabolism |
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Electrophiles, free radicals, nucleophiles, and redox-active compounds are often generated through ________ and these chemical species can react indiscriminately w/ target macromolecules to exert their toxic effects.
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Biotransformation
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What are 5 general mechanisms of action of toxins?
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1) Mimic actions of normal nutrients, hormones, neurotransmitters
2) Stimulate or block receptors, enzymes can be inactivated or inhibited 3) Electrophiles, free radicals, nucleophiles and redox-active compounds are generated and can react with target macromolecules 4) Alter cell membrane 5) Cellular production of vital proteins and regulation of gene expression w/in cells |
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What are 4 ways that free radicals cause cellular macromolecule damage?
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1) Free radicals
2) Superoxide -Active oxygen -GSH 3) Lipid peroxidation 4) Depletion of protein thiol groups -Glutathione |
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What are the 2 major cyp enzymes?
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CYP1A and CYP3A
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