endocrinology exam 1 Flashcards
Endocrinology
endocrine gland secretions and interaction between hormones and behaviors
hormones
chemical messengers secreted by endocrine glands into the bloodstream; slow and stable to target other glands, organs, cells, and brain/NS
operate over longer distances than NTs and for longer duration
similar to cytokines of immune system and interact together to shape behavior
Arnold Berthold
Cockerel Castration
- lack of testes = lack of male sexual behavior and lack of male secondary sex characteristics
- androgens like testosterone responsible for maturation and secondary sex characteristics
- reintroduce testes to castrated eunuch = normal male behavior and development
Frank Beach
father of behavioral endocrinology; neural basis for innate behavior
- testosterone in rates with neuroendocrine link
- hormones and behaviors first text
father behavioral endocrinology with neural basis for innate behavior
frank beach
autocrine signaling/communication
diffusion back on to own/same cell type
paracrine communication
local diffusion to other adjacent types of cells
juxtacrine signaling
physical contact
(lead to neuronal signaling)
endocrine signaling/comm
transport via blood circulation
neurocrine signaling
hormone release from nerve cell/neuron to another cell (ex: posterior pituitary)
neural communication
processes extend terminally across synaptic cleft to receptors on dendrites, allowing specificity and economy of secretion
rapid faster communication bc close
more specific targeting/local
less hormone on secretion needed to elicit response
communes electrical and chemical signaling
neurotransmitters
short distances, fast communication
signaling from hypothalamus
neural and endocrine signaling
endocrine system
glands and cells to synthesize and secrete hormones; hormone chemical messenger transported thru blood and target organ/cells for hormones to elicit response
+ and - feedback
negative feedback loop example
hypothalamus releases GnRH to pituitary to release FSH and LH on ovary and testes to release estradiol, progesterone and testosterone
hormones types
amino acid derivatives, peptide hormones, and steroids
adrenal medulla hormones
catecholamines of epinephrine/adrenaline and norepinephrine
humans have 90% Epinephrine and 10% NE
catecholamines
monoamines from adrenal medulla, epinephrine 90% and norepinephrine
regulation of adrenal medulla
Sympathetic NS spinal cord to acetylcholine via chromaffin cells: ganglionic fibers to norepinephrine and adrenal medulla to epinephrine
chromaffin cells
synthesize catecholamines (epi and norepi) in adrenal medulla gland by convert tyrosine to L-DOPA to AADC to Dopamine to PMNT to epi and norepi
cortisol
triggers adrenal medulla positive feedback on PNMT for epinephrine
effects of catecholamines
increase heart rate, vasoconstriction increases BP, decrease insulin secretion, pupil dilation, increase muscle relaxation
steroids
require polar carrier protein in blood
hormones vs NT vs cytokines
hormones last longer duration, more stable, travel longer distance. neurons require synaptic cleft connection - local and fast like juxtacrine signaling comm. less secreted
NTs bind to hormones
neural and endocrine signaling origin
hypothalamus
absence of oxytocin receptors in prairie voles =
no effect
gonadal sex differentiation depends on
chromosomal sex
polypeptide and monoamine hormones typically …
bind with receptors on the cell membrane
hormone secreted by adipose cells
leptin
leptin
secreted by adipose cells
difference between hormones and NT
hormones secreted into circulatory system
requires antibodies
ELISA
castrations occur
before puberty
hormone antagonists
block hormone or NT action
techniques to study testosterone content in blood and location of receptors for hormone in brain
radioimmunology and autoradiography
2 ways hormones affect behavior and how behavior affects hormones
techniques used to study endocrinology
Ablation and replacement, optogenetics, mini-osmotic pump, bioassay (rabbit test for pregnancy), radioimmunology use antibody-antigen binding, immunohistochemistry labels antibodies to show location of hormones in tissue, blot test, insitu hybridization for gene expression
pathway a hormone takes to reach a target cell from production to target cell response
major endocrine glands and examples of hormones secreted from them and that hormones function
anterior and posterior pituitary, adrenal (medulla) glands, gonads, placenta, brain
compare and contrast steroid and peptide hormones
steroid hormones require polar carrier protein molecule
second messangers
surface receptors cause cascade effect
amino acid derivative hormones
polar
peptide hormones
large size, polar, may need carrier protein and bind on cell membrane
steroid hormones
lipids, fat soluble, require polar carrier protein
ablation
remove hormone so behavior ceases
- surgically remove gland
- block or inhibit receptor
- lesion brain
replacement
reintroduce hormone to restore behavior by reimplanting gland or administer supplemental hormone, cease administration of inhibitor, increase hormone concentration. behavior occurs when hormone in high concentration
- use time releases tech to release hormone in natural pattern
challenges to measuring covariance
latency delay to hormone action and pulsatile release of hormone, lab environ may alter hormonal responses
immunohistochemistry
labeled antibodies show location of hormones in tissue
in situ hybridization
for oxytocin receptors, measure gene expression by mrna
hormone agonist
stimulates action
antagonist
binds to receptor of hormones to block response
audioradiography
measure receptors and where receptors are
crispr cas9
viral and plasmid gene transfection
kisspeptin hormone
responsible for sexual maturation/puberty to release GnRH, LH/FSH and testosterone/estrogen
inactivate/mutate kisspeptin
cancer or hypogonadism
hormone receptor binding and activation for hormone types
role of hormones in stress response
cortisol to epinephrine/adrenaline in adrenal medulla
role of hormones in homeostasis
role of hormones in catabolic/anabolic processes
intracrine
intracellular
mini-osmotic pumps
administer hormones for 2-6 weeks as implant in rodents that achieve steady-state serum levels
hormones are secreted…
into circulatory system by glands
tinbergen levels of analysis 1951
mechanistic, evolution, ontogeny
bertholds study concluded
testes produced substances that supported male traits and behaviors
evidence of hormone-behavior interactions
hormonally dependent behavior disappears when the source of hormone is removed
target cell
has specific receptors that may activate cascade of events
ectocrine signaling
from external source - pheromones
endocrine glands
ductless and empty to blood stream
exocrine glands
have ducts or tubes at release site and empty into organ chamber or lumen
- saliva, sweat, mammary
endocrine systems
ductless endocrine glands with rich blood supplies. hormone secretions into blood stream and travel to many cells interacting with cells that express specific receptor for binding. hormone receptors are specific binding site embedded in cell membrane or in cell
hormone receptors
specific binding site on cell membrane or inside cell
- peptide hormone binds membrane
- steroid hormone binds in cell nucleus
water soluble and polar hormones
proteins and small peptide hormones are stored in secretory vesicles with protein matric and stimulus for secretion causes vessel to fuse w membrane for release. receptors expressed on outer cell membrane. G-protein coupled receptor most common
lipid-soluble and non-polar hormones
steroid hormones: readily cross phospholipid bilayers of cell membranes. not stored for release: instead, signal to produce = signal to release and cholesterol is precursor in lipids. require carrier protein for transport in blood.
receptors in nucleus or cytoplasm so pass through lipid bilayers of target cell. hormone enters by diffusion across cell membrane after release from carrier protein. alters rate of gene expression. can be desensitized or down-regulated by internalization. requires second messenger before released into cytosol and can initiate or inhibit enzyme cascade
g-protein coupled receptor
water soluble/polar protein and peptide hormones
receptor in nucleus or cytoplasm
steroid hormone
receptor expressed on outer cell membrane
protein or peptide hormone
protein and peptide hormones
polar and water soluble; require 2nd messenger to be released into cytosol;
made up individ amino acids bound by peptide bonds
peptide hormones
short chain of amino acids
water/blood soluble and polar
stored in secretory vesicles in endocrine cells and released by exocytosis
water/blood soluble and polar
no NOT require carrier protein but protein and peptide hormones stored in secretory vesicles and require 2nd messenger for release into cytosol
half life of protein/peptide hormones
breakdown by peptidases in time to remove 1/2 hormone conc from blood
hypothalamus
master regulator of endocrine below thalamus controlling secretions of hormones;
regulates autonomic NS; connections descend and receives input from limbic structures like amygdala;
made of neural tissue with neural inputs
at base of brain
made of neuronal cell bodies called nuclei
master regulator endocrine
hypothalamus
hormone producing glands in brain
hypothalamus, anterior pituitary and pineal gland
Pineal gland
epiphysis in brain processes optic input of light/dark cycle and secretes melatonin to reg. sleep and as antioxidant protect cells and neurons from oxidative damage
epiphysis
pineal gland in brain
melatonin
released by epiphysis/pineal gland
potent free radical and antioxidant
pituitary gland
under hypothalamus. 2 distinct parts: anterior pituitary releases trophic hormones and posterior pituitary connected to hypothalamus. anterior made from tissue dur embryonic development
neuroendocrine hypothalamus
made of neuronal cell bodies/nuclei
axonal input received from limbic system
controls reproduction and metabolism
contains neurosecretory cells and releases neurohormones in Response to impulse
hypothalamic releasing hormones
small peptide hormones act as NTs
- TRH thyrotropin RH
- GHRH growth hormone
- RnRH gonadotropin
- MRH - melanotropin
- CRH corticotropin RH
2 inhibiting hormones
- GHIH growth hormone inhibitory somatostatin
GnIH - gonadotropin inhibitory
somatostatin
GHIH growth hormone inhibitory hormone released from hypothalamus
-tropin releasing hormones
released by hypothalamus
releases trophic hormones
anterior pituitary gland
RFAmide peptides
arginine - phenylalanine - NH2
ex = kisspeptin and GnIH
kisspeptin as RFAmide peptide
puberty hormone; producing neurons found in arcuate and anterioventral hypothalamus to project to medial pre optic area - the site of GnRH producing neurons
puberty hormone
kisspeptin RFAmide peptide hormone
GnIH
released from hypothalamus and has opposite effects of kisspeptin, inhibits GnRH
pituitary
hypophysis = below brain
hypophysis
pituitary
anterior pituitary region
adenohypophysis has soft tissue origin from roof mouth; prods trophic hormones in response to hypothalamic hormones
posterior pituitary gland
neurohypophysis has neural origin; hypothalamic neurosecretory cells directly release hormone in here
neurohypophysis
posterior pituitary with neural origin
pituitary size
blueberry
communication between hypothalamus and pituitary
portal system with closed blood circuit connecting capillary beds of hypothalamus to anterior pituitary releasing hormones.
1. Anterior: axon terminals of hypothalamic neurons release neurohormones near capillaries for portal vessels
2. anterior pituitary hormones leave gland via blood
1. Posterior: hypothalamic neurons produce vasopressin and oxytocin and transport them to posterior pituitary and diffuse into capillaries.
anterior pituitary hormones
trophic factors protein hormones are releasing RH and inhibitory IH hormones from hypothalamus, small peptide hormones
trophic factors
anterior pituitary protein hormones
anterior pituitary hormone cells release:
- glycoproteins of carbohydrates include gonadotrophin LH, FSH, and TSH thyroid stimulating
- simple proteins: growth hormone GH and prolactin PL
- corticotrope cell products: ACTH derived from POMC giant precursor/hormone derivative
POMC
pre-opiomelanocortin giant precursor to ACTH
POMC derivatives
ACTH is most commonly known hormone derivative
other POMC products: lipotrophins and endogenous opioids that suppress pain like B-endorphin and Met-enkephalin
endogenous opioids
Met-enkephalin and B-endorphin suppress pain under stress and are POMC products
polypeptide and monoamine hormones typically…
bind to surface receptors on cell membrane
pituitary is controlled by…
hypothalamus
secreted by posterior pituitary gland
oxytocin and vasopressin
released by anterior pituitary
LH, FSH, TSH, GH, ACTH, and prolactin
regulated by hypothalamic stimulation
growth hormone, FSH, LH, and ACTH
net effect of vasopressin actions
increase arterial blood pressure
autocrine hormones feedback
to influence same kinds of cells that secreted them
posterior pituitary actions
oxytocin and vasopressin (arginine vasopressin = antidiuretic hormone ADH)
in contrast in anterior pituitary, NO interior portal system
vasopressin
arginine vasopressin = antidiuretic ADH hormone
antidiuretic hormone ADH
arginine vasopressin released by posterior pituitary hypothalamus neurosecretory cells
posterior pituitary secretions
oxytocin and vasopressin synthesizes in magnocellular neuron cell bodies of hypothalamus: supraoptic and paraventricular
neuroendocrine axons travel down infundibulum to posterior pituitary (neurohypophysis) and can be releases as fast as neuronal impulse conducted
posterior pituitary/neurohypophysis hormones synthesis
on magnocellular neuron cells bodies of hypothalamus
ADH and Oxy are nonapeptides = 9 amino acids
produced from 2 prohormones after packaging by Golgi bodies into prohormones + carrier proteins = neurophysins
- proxyphysin = oxytocin + neurophysiology 1
- propressophysin = AVP + neurophysiologies 2 + glycopeptide
binding to carrier protein increases half life
neurophysins
prohormones + carrier proteins packaged in Golgi
nonapeptides
oxytocin and ADH are 9 amino acids produced from 2 prohormones/neurophysins
neurophysins carrier protein
binding increases half life of hormones by 10x
oxytocin
released from posterior pituitary and important to enhance uterine contractions and for milk letdown reflex
oxytocin for contractions
uterus only sensitive when oxytocin receptors are highly expressed
patterns of high estrogen + progesterone starting to FALL triggers increase in oxytocin receptor expression
milk letdown reflex
mechanical stimulation of nipple and associative learning/enviro triggers oxytocin release
oxytocin is NOT essential for
milk letdown, pair bonding, nursing pups
enhances
voles lacking oxytocin receptors
still nurse pups and pair bond. oxytocin not required for social attachments
effects of vasopressin ADH
increases arterial blood pressure through vasoconstriction V1R caused by IP3 signal transduction pathway or increase water retention in kidneys V2R
increased arterial blood pressure
vasopressin released by posterior pituitary. 1. V1R vasoconstriction or 2. V2R by increase water retention of kidneys
V1R vasoconstriction
input to hypothalamus, to posterior pituitary to release ADH to blood vessel constriction
IP3 signal pathway
of ADH vasoconstriction; receptor binds hormone and activated G protein dissociates and activates phospholipase PLC to produce second messenger DAG and IP3 from PIP2. IP3 opens Ca2+ channels and with DAG, activate protein kinase C PKC to phosphorylate other enzymes
V2R increase water retention
on renal collecting ducts to increase water permeability, a cAMP-dependent mechanism to decrease urine formation and antidiuretic
alcohol inhibits response
cAMP pathway g-coupled
hormone binding receptor activates G protein and GTP replaces GDP and amplification ensues. GTP hydrolyzed
thyroid gland
follicular tissue - sacs filled with colloid matrix
thyroid hormones
hypothalamic thyrotropin releasing hormone TRH triggers anterior pituitary TSH release. Thyroid prods thyroid hormone in response to anterior pituitary thyroid stimulating hormones TSH
tyrosine is parent amino acid to thyroid hormones (fat soluble tyrosine dipeptides)
increase oxidation rates in tissues, enough stored for 90 days
tyrosine
parent amino acid to thyroid hormones (fat soluble tyrosine dipeptides)
most common endocrine feedback
negative feedback and inhibitor effect in self to decrease further release
- feedback example
hypothalamus releasing GnRH to anterior pituitary
+ feedback example
oxytocin on uterus
thyroid hormones from tyrosine
TSH works thru blood to thyroid gland to activate synthesis of thyroid hormones which increase oxidation rates in tissue, stored for 90 days, need carrier proteins in blood bc fat soluble
- thyroxine T4 most common dipeptide hormone converted to T3
- triiodothyronine T3 biologically active dipeptide hormone
- calcitonin - regulates blood calcium levels made by C cells found in interstitial space between follicles
Thyroxine T4
most common thyroid hormone - tyrosine derived and dipeptide that is fat soluble requiring carrier protein
triiodothyronine T3
biologically active thyroid hormone tyrosine derived
calcitonin
thyroid hormone regulates blood calcium levels made by c cells between follicles
effects of thyroid hormones T3 and T4
- metabolism: increase glucose metabolism to generate heat and adapt to changing temps
in non-hibernating mammals T3 and T4 higher in winter - growth and differentiation: growth promoting actions similar to growth hormone and cretinism: delayed neurological development and cognitive deficits rare since iodine
- reproduction: delayed sex maturation in hypothyroid mammals
cretinism
effect of T3 T4 thyroid hormones cause delayed neurological development and cognitive deficits rare since iodine
parathyroid gland and hormones
4 parathyroid glands embedded in thyroid gland to secrete parathyroid hormone PTH. PTH and calcitonin CT regulate calcium metabolism and both are protein hormones.
PTH parathyroid protein hormones
protein hormones; remove Ca2+ from bone into blood with vitamin D3 it increases gut ca2+ absorption and inhibits phosphate reabsorption form kidney to increase levels of ca2+ in blood. CT opposes effects of PTH on Ca2+ and decreases ca2+ in blood by decreasing removal of ca2+ from bone.
generalized steroid receptor function
steroid hormone receptors usually located in target cell nucleus or cytoplasm and steroid hormones bind to form hormone-receptor complex to move to nucleus. complex acts as transcription factor and binds to hormone response element HRE on DNA to begin transcription of mRNA
hormone receptor complex
steroid hormones bind specific receptors and move to nucleus to act as transcription factor on hormone response element HRE on DNA
gonadal hormones
GnRH gonadotrophin releasing hormone is peptide hormone from hypothalamus which activates anterior pituitary to release gonadotrophin like FSH and LH
GnRH
peptide hormone from hypothalamus activates anterior pituitary to release FSH and LH gonadotrophins
gonadotrophins
direct gonads to release steroid hormones that are derived from cholesterol which are fat soluble and easily cross lipid cell membranes. they are never stores and released as produced. delay from stimulus to response so signal is slow. need water soluble carrier proteins for blood transport and targets have receptors in nucleus or cytoplasm
gonad function
gamete production of sperm/eggs and hormone production to regulate gamete prod and secondary sex characteristics and behaviors
anatomy of testes
seminiferous tubules for maturation of sperm and spermatogenesis
Sertoli cells in basement membrane of seminiferous tubules where embedded sperm cells mature
leydig cells produce androgens in response to LH intestes
leydig cells
produce androgens in response to LH in testes
produce androgens in response to LH in testes
leydig cells
androgens
C19 steroids
hypothalamus to stim anterior pituitary to release gonadotrophin GnRH to prod LH and FSH
adrenal cortex prods DHEA which decreases with age
androgens activate gonadal enzymes:
- testosterone produced in leydig cells
- 5a and 5b dihydrotestosterone
transported in blood by sex hormone binding globulin SHBG carrier protein made in liver
secondary sex characteristics
body shape, body hair, muscular development, voice pitch and libido
primary sex characteristics
internal organs and external genitalia that distinguish sexes
C19 steroids
androgens
androstenedione dehydroepiandrosterone
DHEA produced by adrenal cortex and decreases with age
SHGB sex hormone binding globulin
carrier protein made in liver
menstruation
gametes produced in monthly cycle. 3 phases of ovarian cycle: follicular, ovulation, luteal phase
female gonadal hormones
ovaries produce gametes and hormones with cyclic changes. each ovary contains 500,000 immature follicles
pre-ovulation
mature follicle has thecal and granulose cells that synthesize estrogens in response to FSH and LH as ovum matures an antrum forms around it and fills with liquor follicle containing steroids - mature tertiary follicle = Graafian - ovum erupts and travels into oviduct to uterus
post-ovulation
follicle enlarges to form luteal cells to combine with thecal cells to form corpus luteum = becomes vascularized and secretes progestins - degenerates into corpus albacans
follicular phase
LH receptors appear on theca internal cells. thecal cells prod androgens from cholesterol.
granular cells develop FSH receptors and when stimulated convert androgens into estrogens
at time of ovulation stimulation of granular cells triggers production of progesterone
luteal phase
after ovulation, corpus luteum prods progesterone and some estrogen. progesterone increases in luteal phase to thicken uterus lining
increase in progesterone and thickening uterus lining
luteal phase
