midterm 3 Flashcards
what does an endocrine gland/cell do?
secretes hormones
when are hormones released
upon stimulation
what do target organs have
hormone-specific receptors
what is an endocrine disrupting substance
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
what are the critical windows of exposure
exposure during early life stages may cause irreversible effects on organisms
exposure during reproductive endocrine processes affect populations
what is atrazine used for
herbicide
broadleaf weed control on crops
systemic photosynthesis inhibitor
what effects does atrazine have
impairs gonad development and reproduction
what enzyme does atrazine effect
aromatase
where is atrazine banned
in EU
briefly in BC (in 2012)
where is atrazine not banned
canada and us
what are the atrazine water guidelines in Canada and us
canada: DW: 5 μg/L, FW: 1.8 μg/L
US: DW: 3μg/L, FW: 10μg/L
what is endocrinology
study of endocrine glands and their secretions (hormones)
what is the basic definition of endocrine glands
ductless glands that secrete hormones into blood
are hormones always produced by ductless glands
no
what secrete hormones
small groups of cells, individual cells, or cells within various organs
is secretion from an endocrine gland or cell unihormonal
no
are multiple active chemicals produced by a cell
yes
do most hormones have multiple production sites
yes
are hormones only secreted into bloodstream
no, they are not only blood borne
where are non-blood places hormones can be released
into lymph or extracellular fluids
how does hormone action vary
it varies according to state of the target site
may be determined by the receptors on target cell
do hormones act only on distant target sites
no
what are autocrine signalling
cell targets itself
what is paracrine signalling
targets nearby cell
what did the evolution of multicellular organisms make necessary
to have coordinating systems to regulate and integrate the function of different cells
what are the 2 mechanisms of hormone action
water soluble hormones
lipid soluble hormones
what hormones are water-soluble
all amino acid based hormones except thyroid hormones
can water soluble hormones enter target cell
no
what do water soluble hormones target
act on plasma membrane receptors
how do water soluble hormones work
coupled G proteins to intracellular second messengers that mediate the target cell’s response
what hormones are lipid-soluble hormones
steroid and thyroid hormones
what do lipid soluble hormones act on
act on intracellular receptors that directly activate genes
what are the mechanisms of xenobiotic disruption of endocrine system
hormone receptor agonist
hormone receptor antagonist
what is a hormone receptor agonist
hormonal mimic
toxicant can bind to receptor and induce a hormonal response
what are hormone receptor antagonist
hormonal block
blocks receptor so hormone can’t bind and as a result blocks response
what are the consequences of receptor mediated signalling
produce a non-,monotonic dose/concentration - response curves
what is a non-monotonic dose response
curve whose slope changes direction within range of doses tested
what are the consequences of receptor-meditated signalling
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
how do EDCs break traditional toxicology concepts
higher dose =/= more toxic
low dose = more toxic
how does DDT effect alligators
developmental abnormalities of gonads
abnormal sex hormone concentrations
egg and embryonic abnormalities
adverse effects on reproductive endocrine system
is hormone action life stage specific
development is the most sensitive time for EDC effects
what are the 3 lines of evidence that fuel concerns over endocrine disruptors
- 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
what are the EDS endpoints set out by Canadian Government
reproduction and development are major endpoints
what countries implement EDS testing
US, Japan, EU require information about endocrine disrupting effects of chemicals (US most explicit)
Canada: no mandatory testing
what are the effects of pulp and paper mill effluent on fish downstream
decrease in sex steroids, gonad size and delayed sexual maturity
what is environmental effects monitoring (EEM)
pulp mill effluent monitoring program
goals based on Fisheries Act
what does EEM test and how often
sub lethal toxicity testing of effluent
biological monitoring
every 3 years but if no effect then every 6 years
what are BPA effects
estrogenic
abnormal penile/urethra development in males
early sexual maturation In females
increased neurobehavioral problems
increased childhood obesity and onset diabetes
what are 2 fish reproduction screening assay endpoints
vitellogenin
secondary sex characteristics
what is vitellogenin
synthesized and secreted by the liver under estrogen stimulation, transported in the blood to the ovary, taken up by growing oocytes, develops yolks
are tubercles normal in males and females
males
what causes tubercle production in males and females
androgen
what does endogenous mean
produced within ( ex: androgen in males)
what does exogenous mean
origin from outside origins (ex: androgen in females)
what is linuron
ureic based herbicide
what is the mode of action of linuron
anti-androgenic mode of action
(inhibits androgen mediated )
what are the effects of ethynyl estradiol
vitellogenin effects = gonad histopathology = population crash
