Term
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Definition
| it is the study of the adverse effects of chemical or physical agents on living organisms |
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Term
| what are the 3 basic divisions of toxicology |
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Definition
| they are descriptive, mechanistic, and regulatory |
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Term
| what is the goal of all three divisions of toxicology? |
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Definition
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Term
| what is mechanistic toxicology? |
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Definition
| the study of the cellular, biochemical, and molecular mechanisms by which chemicals exert toxic effects on living organisms |
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Term
| what is descriptive toxicology? |
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Definition
| the testing of toxicity to provide information for safety evaluation and regulatory requirements. This is where animal testing is involved. |
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Term
| what is regulatory toxicology? |
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Definition
| the deciding whether or not a drug or chemical poses a sufficiently low risk to be marketed for a stated purpose, based on data provided by mechanistic and descriptive toxicologists. |
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Term
| what is forensic toxicology? |
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Definition
| hybrid of chemistry and toxicological principles, focuses on the medicolegal aspects of harmful effects of chemicals on humans and animals |
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Term
| what is clinical toxicology? |
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Definition
| the study of disease caused by or uniquely associated with toxic substances |
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Term
| what is environmental toxicology? |
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Definition
| study of the impact of chemical pollutants in the environment on biological organisms. |
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Term
| what is the formal definition of a poison? |
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Definition
| an agent capable of producing a deleterious response in a biological system. |
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Term
| virtually every known chemical has the ability to produce what? |
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Definition
| injury or death if present in sufficient amounts |
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Term
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Definition
| the dosage that causes death in 50% of the exposed organisms |
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Term
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Definition
| toxic substances produced by biological systems such as plants, animals, fungi or bacteria. |
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Term
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Definition
| toxic substances produced by, or are a by-product of, human activities |
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Term
| what are the 4 ways in which toxic substances can be classified? |
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Definition
| by target organs, use, source, and effect |
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Term
| what causes a chemical allergy reaction or sensitization reaction? |
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Definition
| a previous sensitization to that chemical or a structurally similar one, resulting in an immunologically mediated adverse reaction that are sometimes very severe and can be fatal. |
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Term
| what is a chemical idiosyncracy? |
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Definition
| a genetically determined abnormal reactivity to a chemical, could take the form of extreme sensitivity or extreme insensitivity to a chemical |
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Term
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Definition
| when effects of the toxic substance occur at the site of first contact between the biological system and the toxicant |
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Term
| what are systemic effects? |
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Definition
| effects of a toxic substance that are absorbed and distributed from its entry point to a distant site, to where deleterious effects are produced |
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Term
| when chemicals combine to produce an "additive" effect, what does this mean? |
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Definition
| means the two chemicals give an effect equal to the addition of the two chemicals given individually (2+2=4) |
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Term
| what is a synergistic effect? |
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Definition
| when the combined effects of two chemicals are substantially greater than the two of them would be alone (2+2=20) |
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Term
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Definition
| when two chemicals, one without a toxic effect and one with a toxic effect, combine to produce a substantially greater effect than the toxic substance alone would give (0+2=10) |
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Term
| define antagonism due to chemical interaction. |
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Definition
| when two chemicals are administered together that interfere with each other's actions or one interferes with the action of the other. |
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Term
| what are the four major types of antagonism in chemical interaction? |
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Definition
| functional, chemical/inactivation, dispositional, and receptor |
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Term
| define functional antagonism |
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Definition
| when two chemicals cancel eachother out bc they produce opposite effects on the same physiological function |
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Term
| define chemical antagonism |
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Definition
| a chemical reaction between two compounds that produces a less toxic product |
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Term
| define dispositional antagonism |
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Definition
| when the absorption, biotransformation, distribution, or excretion of a chemical is altered so that the concentration and/or duration of the chemical at the target organ are diminished. |
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Term
| define receptor antagonism |
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Definition
| occurs when two chemicals that bind to the same receptor produce less of an effect when given together than the addition of their separate effects (2+2=3) |
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Term
| what are receptor antagonists often called? |
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Definition
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Term
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Definition
| a state of decreased responsiveness to a toxic effect resulting from prior exposure |
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Term
| whare are the major routes by which toxins can enter the body? |
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Definition
| gastrointestinal tract, lungs, skin, and other parenteral routes. |
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Term
| toxic agents produce the greatest effect and the most rapid response when administered where on the body? |
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Definition
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Term
| order insertion routes from most to least effective in terms of toxicity (8) |
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Definition
| intravenous, inhalation, intraperitoneal, subcutaneous, intramuscular, intradermal, oral, dermal |
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Term
| the route of administration of a toxic substance can determine/influence what? |
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Definition
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Term
| what are the 4 types of exposure used in laboratory testing and what are the lengths of each? |
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Definition
| acute-less than 24 hrs, subacute- repeated exposure for a month or less, subchronic- repeated exposure for 1 to 3 months, chronic- repeated exposure for more than 3 months |
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Term
| In human exposure, duration and frequency labels are less defined than in the laboratory. what are the 3 commonly used levels of toxic exposure? |
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Definition
| acute (single incident or episode), subchronic (repeatedly over several weeks or months), chronic (repeatedly for several months or years) |
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Term
| what is the name for the relationship between characteristics of exposure and spectrum of toxic effects? |
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Definition
| dose-responce relationship |
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Term
| what are the two kinds of dose-response relationships? |
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Definition
| graded response and quantal dose-response |
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Term
| what is a graded response relationship? |
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Definition
| the response of an individual organism to varying doses of a chemical |
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Term
| what is a quantal dose-response relationship? |
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Definition
| characterizes the responses to different doses in a whole population (as in, 50% of people died at __ amount) |
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Term
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Definition
| the "effective dose" or a dose at which a toxin produces a response in 50% of a population in a quantal dose-response relationship |
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Term
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Definition
| a concept that can be graphed to convey that some nonnutritional toxic substances can be beneficial at low doses but produce adverse effects at high doses |
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Term
| how is mechanistic toxicology useful? |
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Definition
| it helps to identify whether or not adverse responses in experimental animals are relevent to humans |
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Term
| how is descriptive toxicology useful? |
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Definition
| yeild information to evaluate risks posed on humans and the environment due to exposure |
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Term
| give 2 examples of administrations that conducts business with respect to regulatory toxicology |
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Definition
| FDA, food and drug administration and EPA, Environmental Protection Agency |
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Term
| which effect, local or systemic, do most toxins produce? |
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Definition
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Term
| what are the two mechinisms in which tolerance develops? |
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Definition
| one mechanism is due to a decreased amount of toxicant reaching the site where the toxic effect is produced, two is due to a reduced responsiveness of a tissue to the chemical |
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Term
| what kinds of proteins in the body can act on toxic chemicals to cause them to interfere with the body's normal cellular biochemistry and physiology? |
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Definition
| enzymes that act on toxins in the body (can make matters worse) |
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Term
| what are individual dose-reponse relationships characterized by? |
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Definition
| increase in the severity of the response |
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Term
| how are individuals classified in a quantal dose-response relationship? |
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Definition
| either "responder" or "non-responder" |
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Term
| when are LD50 and ED50 the same? |
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Definition
| when death is the measured endpoint |
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Term
| what is the term for individuals that are more susceptible to a toxin than other individuals in the same population? |
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Definition
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Term
| what is the term for individuals that are less susceptible to a toxin than other individuals in the same population? |
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Definition
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Term
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Definition
| a chemical or substance that is foreign to an organism or biological system |
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Term
| the concentration of a chemical at the site of action is usually proportional to what? |
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Definition
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Term
| what are 4 factors that can affect disposition, leading to an abnormal concentration to dose relationship? |
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Definition
1-low rate of absorption
2-toxicant aggregates in tissue instead of target organ
3-biotransformation of chemical may decrease toxicity
4-rapid elimination of the toxic substance |
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Term
| what are the three major barriers that separate higher organisms from an environment containing a large number of chemicals? |
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Definition
| skin, lungs, and alimentary canal |
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Term
| how many target organs can a chemical have? |
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Definition
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Term
| in what two ways can a toxicant pass through a cell? |
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Definition
| special transport or passive transport |
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Term
| the cell expends no energy when a toxicant enters the cell through _______ transport |
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Definition
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Term
| "toxicokinetics" has two definitions. what are they |
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Definition
-the description of the rate that a chemical will enter the body and what will happen once it enters
-is the quantitation of the time course of toxicants in the body during the processes of absorption, distribution, biotransformation, and excretion or clearance of toxicants |
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Term
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Definition
| the molecular, biochemical, and physiological effects of toxicants or their metabolites in biological systems |
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Term
| what are the two types of passive transport? |
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Definition
| simple diffusion and filtration |
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Term
| what are the three types of special transport (requires energy by cell) |
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Definition
| active transport, facilitated diffusion, and engulfment (phagocytosis and pinocytosis) |
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Term
| what are the four types of reactions in which a toxicant binds to its target molecule? |
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Definition
| covalent bonding, enzymatic reaction, electron transfer, non-covalent bonding |
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Term
| what are some examples of molecular targets? |
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Definition
| lipids, proteins, nucleic acids (all macromolecules pretty much) |
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Term
| define membrane transport (toxicologically) |
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Definition
| the collection of mechanisms that regulate the passage of solutes such as ions and small molecules through biological membranes (namely lipid bilayers) that contain proteins embedded in them. |
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Term
| what are 5 factors that affect the transport of chemicals across a cell's membrane? |
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Definition
| molecular weight and shape, molecular charge, lipid solubility, membrane composition, membrane thickness |
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Term
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Definition
| a non-electrolite or an un-ionized form of an acid or base enters across the cell membrane without expending metabolic energy and in the direction of the electrochemical potential gradient |
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Term
| define filtration of a substance through a cell membrane |
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Definition
| movement of water and solute molecules across the cell membrane due to hydrostatic pressure generated by the cardiovascular system. Depending on the size of the membrane pores, only solutes of a certain size may pass through it |
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Term
| what is another name for facilitated diffusion? |
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Definition
| carrier-mediated diffusion |
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Term
| deine facilitated diffusion |
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Definition
| the movement of molecules across the cell membrane via special transport proteins that are embedded within the cellular membrane (requires energy) |
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Term
| _____ transport requires energy |
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Definition
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Term
| what is endocytosis and how is it used |
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Definition
| the process by which cells absorb molecules (such as proteins) by engulfing them. It is used by all cells of the body because most substances important to them are large polar molecules that cannot pass through the hydrophobic plasma or cell membrane |
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Term
| what kind of proteins typically catalyze an active transport of a chemical across a membrane? |
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Definition
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Term
| how does primary active transport work? |
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Definition
| energy from hydrolysis of ATP is directly coupled to the movement of a specific substance across a membrane independent of any other species |
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Term
| what are the two kinds of active transport? |
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Definition
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Term
| how is secondary active transport different from primary active transport? |
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Definition
| by the way energy is used - the required energy is derived from energy stored in the form of concentration differences in a second solute. there is no direct coupling of ATP; instead, the electrochemical potential difference created by pumping ions out of the cell is used |
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Term
| the similarity between active and passive transport across membranes is what? |
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Definition
| they both require carrier proteins |
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Term
| during passive mediated transport, the process is _______ when the concentration gradient is high |
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Definition
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Term
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Definition
| it is used primarily for the absorption of extracellular fluids (ECF), and, in contrast to phagocytosis, generates very small vesicles. |
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Term
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Definition
| the process whereby toxic agents cross body membranes and enter the bloodstream. |
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Term
| what is the blood-to-gas partition coefficient? |
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Definition
| the solubility ratio of the concentration of chemical in the blood and chemical in the gas |
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Term
| To be absorbed through the skin, a toxicant must: |
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Definition
pass through the epidermis or the appendages (sweat and sebaceous
glands and hair follicles) |
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