Effects on toxicity (lec2) Flashcards
What is homeostatic regulation?
Allows organisms to function effectively in a broad range of conditions - variables regulated so internal environment the same.
List some environmental impacts on toxicity
Organo complexes Salinity Water Hardness pH Temperature
How is methyl-mercury formed, and name some effects
Inorganic mercury (from storm runoff and rainfall) is transformed by NATURAL SULPHATE REDUCING BACTERIA into methylmercury.
It is rapidly taken up by organisms but is slowly eliminated from the body (bad for fish) BIOACCUMULATION.
Disorders of the brain, reproductive and immune system
temperate example of environmental effects on toxicity
Alexandarium tamarense - a dinoflagellate (planktonish)
Measured in different water temperature and different light intensities
Growth rate decreased with decrease in water temp and light intensity.
Interactions with other toxins - what is additive?
When the sum of the combined chemicals is the same as the individual value of each added together
e.g copper and zinc
Interactions with other toxins - what is antagonism
When the effect of the two elements is less than individual values combined
e.g zinc reduces cadmium
se reduces hg
ca reduces pb and cd.
Finally synergism?
When the combined effect is more than the two individual values added together.
e.g cu with cl,zn,cd,hg
Name biological effects on toxicity
Age Life cycle Gender Acclimatisation Genetic constitution Nutritional state Genetic resistance to pollutants (herbicide doses)
Complications with effects of toxicity
Delayed impacts
Formation of metallothioneins - low molecular weight metal binding proteins - hard to remove
Granular storage of metals - cu ca and fe granules
What is detoxication?
Removal of toxic substances from a living organism
Difference between acute and chronic exposure
Acute - no longer than a day
Chronic - extended period of time
What is bioaccumulation
Chemical concentration in an organism exceeding that of the surrounding medium. Results from all exposure routes e.g dietary absorption, respiration,skin absorbtion
What is bioconcentration
Bioconcentration is the accumulation of a chemical in or on an organism when the source of chemical is solely water. When element concentration exceeds the outside dose in a water column.
toxicity experiment issues
Reproducing environmental conditions
Immiscible pollutants (not mixable)
Solubility - e.g PCBS readily penetrate skin
Species related - Non specific sub lethal effects
