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12 Cards in this Set
- Front
- Back
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At which stages of the reproductive cycle can toxicants interfere? |
All stages from egg production to birth. 1) Ova and sperm production and function 2) Effective delivery of sperm for fertilization 3) Effective fertilization 4) Implantation of fertilized ovum 5) Embryo and fetus development 6) Delivery |
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How do reproductive toxicants act? (2 mechanism) |
1)Directly on reproductive organs and germ cells 2)Indirectly by influencing hormone levels |
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What is teratogenesis? |
The production of congenital defect in the developing embryo |
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What are teratogens? |
Agents that causes congenital defects in the developing embryo. |
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How do teratogens act? |
They exert a toxic effect on the embryo -later stage than reproductive toxicants as the egg has already been fertilized and implanted |
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What is DES? |
Diethylstilbestrol - a synthetic estrogenic chemical used to prevent miscarriages - in utero exposure will show uterine and vaginal cancer in daughters - current uses: cattle, morning after pill |
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What are the two types of birth defects? |
1) Readily detected malformations 2) Subtle effects |
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What are some examples of readily detected malformations? |
- spina bifida - hydrocephalus - cleft palate |
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During which period of development do most structural deformities occur? |
During the first trimester. - first 12 weeks |
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What is thalidomide? |
A known human teratogen. - In the 1950's, used as a tranquilizing agent for pregnant women - Resulted in phocomelia - infants born with shortened or no limbs - Withdrawn from use in 1962 |
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What is salicylate? |
A potent animal teratogen - found in asprin |
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What are the 4 possible mechanisms of teratogens? |
1) Interference with DNA replication 2) Interference with metabolism & energy 3) Inhibition of enzymes 4) Damage of cell membranes |
