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Environmental Toxicology > midterm 3 > Flashcards

midterm 3 Flashcards

1
Q

what does an endocrine gland/cell do?

A

secretes hormones

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2
Q

when are hormones released

A

upon stimulation

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3
Q

what do target organs have

A

hormone-specific receptors

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4
Q

what is an endocrine disrupting substance

A

exogenous substance or mixture that alter functions of the endocrine system and causes adverse health effects in an intact organism or its progeny or population

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5
Q

what are the critical windows of exposure

A

exposure during early life stages may cause irreversible effects on organisms

exposure during reproductive endocrine processes affect populations

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6
Q

what is atrazine used for

A

herbicide

broadleaf weed control on crops

systemic photosynthesis inhibitor

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7
Q

what effects does atrazine have

A

impairs gonad development and reproduction

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8
Q

what enzyme does atrazine effect

A

aromatase

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9
Q

where is atrazine banned

A

in EU

briefly in BC (in 2012)

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10
Q

where is atrazine not banned

A

canada and us

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11
Q

what are the atrazine water guidelines in Canada and us

A

canada: DW: 5 μg/L, FW: 1.8 μg/L

US: DW: 3μg/L, FW: 10μg/L

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12
Q

what is endocrinology

A

study of endocrine glands and their secretions (hormones)

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13
Q

what is the basic definition of endocrine glands

A

ductless glands that secrete hormones into blood

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14
Q

are hormones always produced by ductless glands

A

no

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15
Q

what secrete hormones

A

small groups of cells, individual cells, or cells within various organs

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16
Q

is secretion from an endocrine gland or cell unihormonal

A

no

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17
Q

are multiple active chemicals produced by a cell

A

yes

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18
Q

do most hormones have multiple production sites

A

yes

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19
Q

are hormones only secreted into bloodstream

A

no, they are not only blood borne

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20
Q

where are non-blood places hormones can be released

A

into lymph or extracellular fluids

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21
Q

how does hormone action vary

A

it varies according to state of the target site

may be determined by the receptors on target cell

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22
Q

do hormones act only on distant target sites

A

no

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23
Q

what are autocrine signalling

A

cell targets itself

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24
Q

what is paracrine signalling

A

targets nearby cell

25
Q

what did the evolution of multicellular organisms make necessary

A

to have coordinating systems to regulate and integrate the function of different cells

26
Q

what are the 2 mechanisms of hormone action

A

water soluble hormones

lipid soluble hormones

27
Q

what hormones are water-soluble

A

all amino acid based hormones except thyroid hormones

28
Q

can water soluble hormones enter target cell

A

no

29
Q

what do water soluble hormones target

A

act on plasma membrane receptors

30
Q

how do water soluble hormones work

A

coupled G proteins to intracellular second messengers that mediate the target cell’s response

31
Q

what hormones are lipid-soluble hormones

A

steroid and thyroid hormones

32
Q

what do lipid soluble hormones act on

A

act on intracellular receptors that directly activate genes

33
Q

what are the mechanisms of xenobiotic disruption of endocrine system

A

hormone receptor agonist

hormone receptor antagonist

34
Q

what is a hormone receptor agonist

A

hormonal mimic

toxicant can bind to receptor and induce a hormonal response

35
Q

what are hormone receptor antagonist

A

hormonal block

blocks receptor so hormone can’t bind and as a result blocks response

36
Q

what are the consequences of receptor mediated signalling

A

produce a non-,monotonic dose/concentration - response curves

37
Q

what is a non-monotonic dose response

A

curve whose slope changes direction within range of doses tested

38
Q

what are the consequences of receptor-meditated signalling

A

hormones act at low levels

largest effect at lower doses

saturation of receptors and thus effect at high doses

desensitization and down-regulation of receptors at high hormone levels

too many unused chemicals are bad for cell, can cause cell death

39
Q

how do EDCs break traditional toxicology concepts

A

higher dose =/= more toxic

low dose = more toxic

40
Q

how does DDT effect alligators

A

developmental abnormalities of gonads

abnormal sex hormone concentrations

egg and embryonic abnormalities

adverse effects on reproductive endocrine system

41
Q

is hormone action life stage specific

A

development is the most sensitive time for EDC effects

42
Q

what are the 3 lines of evidence that fuel concerns over endocrine disruptors

A
  • increasing trends of many endocrine related disorders in humans
  • observation of endocrine-related effects in wildlife populations
  • lab studies linking chemicals with endocrine effects to disease outcomes
43
Q

what are the EDS endpoints set out by Canadian Government

A

reproduction and development are major endpoints

44
Q

what countries implement EDS testing

A

US, Japan, EU require information about endocrine disrupting effects of chemicals (US most explicit)

Canada: no mandatory testing

45
Q

what are the effects of pulp and paper mill effluent on fish downstream

A

decrease in sex steroids, gonad size and delayed sexual maturity

46
Q

what is environmental effects monitoring (EEM)

A

pulp mill effluent monitoring program

goals based on Fisheries Act

47
Q

what does EEM test and how often

A

sub lethal toxicity testing of effluent
biological monitoring

every 3 years but if no effect then every 6 years

48
Q

what are BPA effects

A

estrogenic

abnormal penile/urethra development in males

early sexual maturation In females

increased neurobehavioral problems

increased childhood obesity and onset diabetes

49
Q

what are 2 fish reproduction screening assay endpoints

A

vitellogenin

secondary sex characteristics

50
Q

what is vitellogenin

A

synthesized and secreted by the liver under estrogen stimulation, transported in the blood to the ovary, taken up by growing oocytes, develops yolks

51
Q

are tubercles normal in males and females

A

males

52
Q

what causes tubercle production in males and females

A

androgen

53
Q

what does endogenous mean

A

produced within ( ex: androgen in males)

54
Q

what does exogenous mean

A

origin from outside origins (ex: androgen in females)

55
Q

what is linuron

A

ureic based herbicide

56
Q

what is the mode of action of linuron

A

anti-androgenic mode of action

(inhibits androgen mediated )

57
Q

what are the effects of ethynyl estradiol

A

vitellogenin effects = gonad histopathology = population crash

58
Q
A

Environmental Toxicology (3 decks)

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