Topic 03 Flashcards
This is the evidence contributed by circumstances or deduced from various occurrences and facts. Not considered as strong evidence.
Circumstancial or Moral Evidence
This includes symptoms observed during poisoning. This is not conclusive though some diseases may be present and similar symptoms may be observed as those of poisoning.
Symptomatic Evidence
This evidence obtained by chemical analysis of the suspected substances, or the vomitus or secretion of the body.
Chemical Evidence
The evidence from examination of tissues and organs after death. It is also known as “Autopsy”.
Post-Mortem Evidence
This is obtained by administering the suspected substances to some living animals and noting the effects of symptoms. This is not a very conclusive procedure since tolerance may not be the same as in man.
Experimental Evidence (Physiological Tests)
The major route of entry of poisons in the industrial setting. Atmospheric pollutants gain entry by inhalation.
Inhalation
Give example/s of toxicants that may enter through inhalation.
- Sulfur Dioxide
- Nitrogen Oxide
- Carbon Monoxide
- Carbon Dioxide
This is the lowest concentration of a certain odor compound that is perceivable by the human sense of smell.
Odor Threshold
This is result of ingesting contaminated food or beverages, touching the mouth with contaminated fingers, or swallowing inhaled particles.
Ingestion
This bypasses the protection provided by the intact skin and provides direct access in the blood stream.
Injection
It occur in hypersensitive individuals or after sensitization in allergic or sensitized persons. It often requires the binding of a chemical (hapten) to endogenous protein to be recognized by the immune system. Reaction ranges from skin irritation to anaphylactic shock.
Allergic Reactions
It occur in individuals who have genetic polymorphisms that lead to structural changes in biomolecules, making them very sensitive or insensitive to a chemical.
Idiosyncratic Reactions
Most chemicals exert their effects soon after exposure. Others may be delayed for days to years.
Immediate vs. Delayed Toxicity
Depends on the tissue’s ability to regenerate itself at a variety of levels: molecular, cellular, and tissue.
Reversible vs. Irreversible Effects
Corrosives and irritants act locally. Little goes systemic.
Local vs. Systemic Toxicity
The combined effect is the same as the sum of effects when given alone.
Additive
The combined effects are much greater than the sum of effects when given alone.
Synergistic
The exposure to a chemical with no toxicity increases the toxicity of another compound.
Potentiation
The co-administration of two chemicals interferes with the toxicity of both or one of them.
Antagonism
Four (4) Types of Antagonism
- Functional Antagonism
- Chemical (or Inactivation)
- Dispositional Antagonism
- Receptor Antagonism
Chemicals counterbalance each other by exerting opposite effects on a physiological function.
Functional Antagonism
A chemical reaction between two compounds leads to less of the toxic compound.
Chemical (or Inactivation)
This is an antitoxin active against the venom of a snake, spider, or other venomous animal or insect.
Antivenin
Disposition of toxic chemicals is changed so that the concentration and/or duration is diminished (e.g., Ipecac).
Dispositional Antagonism
Chemicals compete for the same receptor, decreasing the effective binding of toxic compounds (e.g., Naloxone and Morphine, Tamoxifen and Estradiol).
Receptor Antagonism
A state of decreased responsiveness due to a prior exposure to the same or a structurally similar chemical in an individual.
Tolerance
A decreased amount of chemical reaches the site where the effect is produced (e.g., Carbon Tetrachloride).
Dispositional Tolerance
The same amount of chemical reaches the site, but the target receptor response decreased.
Receptor Tolerance
A change in the susceptibility to a chemical at the population level. A selective process (evolution) by which sensitive individuals do not survive and only those with a genetic trait that accommodates the chemical survive.
Resistance
This is applied to the pharmacokinetics of toxic doses of chemicals, since the toxic effects of an agent may alter normal mechanisms for absorption, metabolism, or excretion of a foreign material.
Toxicokinetic
Two (2) Types of Special Aspects of Toxicokinetics
- Volume of Distribution (Vd)
- Clearance
Defined as the apparent volume into which a substance is distributed.
Volume of Distribution (Vd)
A measure of the volume of plasma that is cleared of drugs per unit of time.
Clearance
Two (2) Types of Kinetic Parameters
- First Order Kinetics
- Zero Order Kinetics
