Endocrine toxicology Flashcards
what is endocrinology
the study of hormones
four characteristics of hormones
produced in glands
transported in blood
interact with receptors
cause change in target cell
major endocrine glands
hypothalamus and pituitary thyroid and parathyroids adrenals stomach pancreas gonads
endocrine system regulates three things
homeostasis
metabolism
reproduction
two things about the endocrine systems interaction with the neural system
endocrine system is slower
works over a longer time period
three types of hormones
peptide hormones
steroid hormones
amino acid derived hormones
three characteristics of peptide hormones
chains of amino acids
pre-synthesized and stored
water soluble
three characteristics of steroid hormones
made from cholesterol
poorly water soluble
no storage
two characteristics of amino acid hormones
tyrosine formed into the growth hormone thyroxine
catecholamines: adrenaline, dopamine
hormones are at ___ concentrations in the blood
low
hydrophobic hormones need
transporters
binding affects biological activity of three things
solubility
half-life
storage
mechanisms of action for hormones always involves
interaction with receptor
mechanism for steroids and thyroids
usually in nucleus, complex binds to response element on DNA to induce transcription
mechanism for peptides, glycoproteins, and catecholamines
receptor in cell membrane facing extracellular matrix
keeps the receptor in the correct confirmation for when the hormone is available for binding
hsp
peptide hormone action
hormone binds to receptor site and protein in the cell gets phosphorylated to activate it
example of hormonal negative feedback system
TRH is produced in the hypothalamus to anterior pituitary which produces TSH to thyroid gland which makes T4 and T3 which can feed back to inhibit hypothalamus and pituitary
principle organizers of the endocrine system
hypothalamus and pituitary
linked by blood vessels to hypothalamus
releases peptide hormones that regulate other endocrine glands
anterior pituitary
extension of nerve cells from hypothalamus, hormones directly released from nerve endings
release oxytocin and vasopressin
posterior pituitary
somatotrophs produce
growth hormone
lactotrophs produce
prolactin
corticotrophs produce
ACTH
thyrotrophs produce
thyroid stimulating
gonadotrophs produce
LH and FSH
five things that cause pituitary toxicity
heavy metals organics pesticides industrial chemicals therapeutic drugs
adrenal cortex produces
cortisol and DHEA and aldosterone
adrenal medulla produces
adrenaline
sympathetic nerve ganglion produces
noradrenaline
adrenal cortex hormones are all derived from
cholesterol
adrenal cortex hormones are synthesized by
cytochrome P450 isoforms mostly
chemicals that cause cellular damage to adrenal gland
DMBA
chemicals that inhibit sterdidogenesis in adrenal gland
CYP inhibitors
blockage of serum binding proteins in adrenal gland
NSAIDs
adrenal cancer can occur in the
medulla
thyroxine (T4)
inactive form
T3 (tri-iodothyronine)
active form
thyroid binding globulin
transporter
function of thyroid gland
regulation of metabolic rate and oxygen consumption
causes excessive hormone production and binding on transport proteins in thyroid gland
PCBs
inhibit iodide uptake for thyroid gland
perchlorate and bromate
thyroid mimics bind to
T3 receptors
three thyroid hormone mimics
bisphenol A
PCB 80
brominated diphenyl ethers
leydig cells produce
androgens
DHEA is converted into
testosterone
testosterone is important for two things
spermatogenesis and secondary male characteristics
testosterone and spermagenosis is regulated by
hypothalamus and pituitary HPT axis
wolffian duct develops into
testis
muellerian duct develops into
fallopian tubes
release of this hormone stimulates production of sex hormones in gonads
GnRH
blood sugar regulation
insulin
blood calcium regulation
parathyroid hormone and vitamin D
kidney function
erythropoietin by kidney
circadian rythms
melatonin by pineal gland
three examples of wildlife effects of endocrine disruption
egg shell thinning
feminization of fish
masculinization of snails
four examples of human effects of endocrine disruption
reduced sperm counts
early onset of puberty
breast/ovarian cancer
hypospadias