Toxicology 1 Flashcards
Define
Toxicology
Study of adverse effects of chemicals in biological systems
Who said
All things are poison and nothing is without poison, only the dose makes a thing not a poison
Paracelsus
Define
ecotoxicology
study of effects of pollution on entire ecosystem
Differentiate
Toxicology vs ecotoxicology
Toxicology: chemicals → bio system
Eco: pollution → entire ecosystem
Relative Toxicity
Relative to dose & relative to person taking dose
Dose-Response Relationship
Quantitative description of the association between exposure & toxic effects produced
Requirements for Dose-Response Relationship to have a toxic effect
3
- Chemical or active metabolite that causes an adverse reaction in the body
- Must have sufficient concentration to have an effect
- Must persist long enough to exert the effect
Considerations for a Dose-Response Relationship
3
- Must be known that response is due to compound exposure
- Response Magnitude should be a function of dose administered
- Should have a quantitative method for measuring response
LD50
Also: what are the units?
Lethal Dose 50
- Dose of chemical that kills 50% of exposed population in a defined time frame
- Dose per kg of bodyweight (mg/kg)
How do we determine LD50?
Rats (aka through toxicology! lol)
Major Routes of Exposure
Contact
Ingestion
Inhalation
Describe
Contact Exposure
What happens?
What does skin absorb & not absorb?
Absorption over time
skin is Hydrophobic & lypophilic
Describe
Ingestion Exposure
- Guts absorb maximum amt of substances it can digest (Bc Body assumes you are responsible)
- “Free for all” down there
Describe
Inhalation Exposure
Inside chest cavity – protection
Toxicant Classifications
3
- Chemical Class
- Source of Exposure
- Organ system affected
How do we classify chemical class?
accdg to functional group
Chemical class examples add for long exam
Source of exposure
To air: ____
To water: ___
To air: ‘emission’
To water: ‘discharge’
List
Organ Systems affected
5
- Liver
- Kidneys
- Spine
- DNA
- Fetus
Main organs usually affected
2
Liver, kidneys
What does the liver do?
Liver breaks down things (alcohol, proteins), Detoxifier
What do kidneys do?
filter waste from blood,
Can pee it out
How is our DNA affected by toxicant?
Once DNA is damaged, DNA replication is at risk
How does the fetus become affected by toxicant?
- Umbilical cord & Amniotic fluid
- Creates its own blood supply
Why do toxicologists favor studying the organ system affected?
it’s easier for them to think about & target
Define
Xenobiotic
chemical foreign to the body
Sequence of response
4
Absorption
Distribution
Metabolism
Excretion
Define
Toxicokinetics
processes in the toxicological sequence
What is the importance of studying toxicokinetics?
Knowing process of response helps you develop treatment against substance
Or prevent it from spreading further
Describe
Absorption
Traversing biological barrier (Aka blood)
Common pathways of absorption
3
Gastrointestinal system
Pulmonary alveoli
Skin
Describe
Absorption through Gastrointestinal system
- Design: nutrient absorption
- Large surface area with numerous transport systems
- Most taken advantage of by pathogens (they will try to enter system)
- Be careful of what you ingest!
Describe
Absorption through Pulmonary alveoli
Gas exchange between air & blood
What gets absorbed through Pulmonary alveoli?
Small particles & aerosols
- Diffusion of most water-soluble compounds
- Lipid-soluble compounds also absorbed
How does Diffusion of most water-soluble compounds happen in the Pulmonary Alveoli?
Mucous lining
more explanation pls
Absorption through Skin
What kinds of compounds can penatrate & not penetrate skin?
- Effective barrier for water-soluble
- Lipid-soluble compounds readily penetrate skin & enter blood stream
2 ways Distribution takes place
Bloodstream
Intestines/Liver
What law does Distribution follow?
laws of diffusion
In distribution through the intestines & liver, [many/few] chemicals are excreted in an unchanged form
few
How are water soluble chemicals excreted?
urine
How are fat soluble chemicals excreted?
Converts to bile first, excreted through feces
What happens when the body doesn’t know how to get rid of a substance?
Stores it (ex. lead deposit in bones)
Define
Biotransformation
enzyme-mediated metabolic conversion
Where does metabolism take place and why?
Mostly in liver, bc rich in metabolic enzymes
Nearly all cells have some capacity for metabolism
Recall: detoxifying organ
What products are usually formed from metabolic transformations (metabolism)?
Products are most polar and less fat soluble (for excretion via urine)
What does the field of carcinogenesis tackle?
When metabolism yields more toxic products than original
T/F
Metabolites cannot combine with cellular nucleophiles
F
They can combine w/ DNA & RNA
What do you call substances that affect the DNA?
mutagen
