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158 Cards in this Set

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  • Back
what is a hormone?
any substance that carries a signal that ultimately renders some change at the cellular level

produced by one cell which passes through circulation and ellicits effects on other cells/tissues
what is an endocrine hormone?
arise in one tissue or gland and travels through the circulation to reach target cell/tissue of different type
what is a paracrine hormone?
hormone which interacts with cells neighboring/near the one which produced it
what is an autocrine hormone?
hormone that interacts with cells of identical type to the ones that produced it
what happens to the visceral fat as it increases?
becomes more heavily infiltrated by macrophages
what is the process by which cortisol is released from the suprarenal glands?
corticotrope releasing hormone stimulates the release of ACTH which stimulates the release of cortisol
what receptors do the thyroid hormones bind to?
intracellular receptors (transcription factors)
what hormones bind to serpentine receptors?
glucagon
parathyroid hormone
leutinizing hormone
thyroid stimulating hormone
growth hormone releasing hormone
what are serpentine receptors?
g-protein coupled receptors which have 7 transmembrane passes
what hormones bind to single pass receptors?
insulin
what hormones bind to cytokine receptors?
erythropoietin (EPO)
growth hormone
prolactin
what hormones bind to guanylyl cyclase-linked receptors?
atrial natriuretic peptide (ANP)
what is the POM gene?
proopioidmelanocortin gene

a gene which provides a variety of hormones depending on what tissue is presenting it
why are oxytocin and vasopressin closely related?
they are very highly conserved proteins, both of which are produced as preproteins and when cleaved supply the hormone and necessary neurophysin
what are enkephalins?
endorphins = naturally produced opioid receptor ligands

met-enkephalin and leu-enkephalin, both from the same gene
what are hypophyseotropic hormones?
releasing factors (dopamine and somatostatin are inhibiting factors) secreted into the hypophysial portal blood from anterior pituitary

GRH, TRH, CRH, PRF, GnRH, dopamine, somatostatin, LHRH
what are the hormones secreted by the neurohypophysis?
oxytocin
vasopressin (ADH)
to where are hormones delivered from the neurohypophysis?
directly into the general circulation
what hormone inhibits the release of prolactin?
dopamine (prolactin inhibiting factor)
from what is dopamine derived?
tyrosine
how is prolactin release regulated?
dopamine inhibits the release of prolactin; this is the major form of regulation, rather than something stimulating prolactin to be released
which hormone inhibits growth hormone secretion?
somatostatin (growth hormone inhibiting hormone)
what causes diabetes incipidus?
deficiency of vasopressin (ADH)
what is polydypsia?
excessive thirst
how are oxytocin and vasopressin produced?
synthesized as prohormones with hormone and neurophysin
what is the function of vasopressin?
regulates body fluid osmolarity
what is the function of oxytocin?
contraction of uterine smooth muscle
contraction of smooth muscle of lactiferous ducts
neurological reward system
by what signalling mechanism do oxytocin and vasopressin function?
cAMP and PKA or PLCgamma signalling
what is the function of somatotrophs?
released from anterior pituitary

target growth hormone secreting cells
what is the function of growth hormone?
induce synthesis of IGFs (insulin-like growth factors)

broadly - stimulate growth of long bones and other tissues
what is the function of lactotrophs?
released by anterior pituitary

target prolactin secreting cells
what is the function of prolactin?
causes differentiation of mammary gland secretory cells

broadly - stimulates milk production
what is the function of thyrotrophs?
released by anterior pituitary

target thyroid stimulating hormone secreting cells
what is the function of thyroid stimulating hormone?
stimulates thyroid production of thyroxine and triiodothyrodine

mainly releases T4
what is the function of corticotrophs?
released by anterior pituitary

target ACTH secreting cells
what is the function of gonadotrophs?
released by anterior pituitary

targets LH- and FSH-secreting cells
what is the function of LH and FSH?
stimulate maturation, differentiation, and hormone secretion of ovaries and testes
how does GH effect the growth of long bones and tissues?
stimulates the synthesis of insulin-like growth factors (IGF-1 and IGF-2)

IGF-1 - postnatal development
IGF-2 - fetal development
what is the function of ACTH?
acts on cells of adrenal glands to stimulate the secretion of glucocorticoids, mineralocorticoids, and androgenic steroids
what is the function of FSH?
acts on sertoli cells to stimulate sperm production or ovum maturation and estradiol production
what is the function of leutinizing hormone?
acts on Leydig cells to increase testosterone
or
acts on corpus luteum to increase progesterone
what is MSH?
melanocyte stimulating hormone
what are the products of the POMC gene in the anterior pituitary?
ACTH
beta-lipotropin

via CRH
what are the products of the POMC gene in the intermediate pituitary?
met-enkephalin
alpha-melanocyte stimulating hormone
corticotropin-like intermediate lobe hormone (CLIP)

via norepinephrine
what are the functions of alpha-melanocyte stimulating hormone?
stimulates melanocytes
regulates inflammatory responses (stimulates synthesis of IL-10)
what are the functions of beta-lipotropin?
stimulates synthesis of hormone-sensitive lipase in adipose tissue
what is the function of CLIP?
corticotropin-like intermediate lobe peptide

hormone which stimulates the release of insulin from beta-cells in the presence of glucose
what is the function of beta-endorphin?
aka met-enkephalin

analgesic effects from cells and neurons by binding nociception receptors
what is nociception?
afferent activity produced in the peripheral and central nervous system by stimuli which have the potential to damage tissue
what type of hormones are dopamine, norepinephrine, and epinephrine?
catecholamines
to what type of receptors do norepinephrine and epinephrine bind?
alpha- and beta-adrenergic receptors
to what type of receptors does dopamine bind?
dopaminergic receptors
what is the signaling mechanism used by alpha1 adrenergic receptors?
IP3 and DAG release
what is the signaling mechanism used by alpha2 adrenergic receptors?
cAMP and PKA
calcium and potassium channels
what is the signalling mechanism used by beta adrenergic receptors?
cAMP and PKA
what is the signalling mechanism used by dopaminergic receptors?
cAMP and PKA
calcium and potassium channels
what is the effect of beta-blockers?
block beta2 adrenergic receptors
(in the vasculature and heart)
what are the functions of dopamine?
pleasure and reward centers in brain

inhibitory neurotransmitter that controls movement
from where is dopamine released?
adrenal medulla
noradrenergic neurons
what is the result of disruption in dopamine function?
psychosis
from where is norepinephrine released?
adrenal medulla
CNS and sympathetic nerves of PNS
what are the functions of norepinephrine?
important for attentiveness, emotions, sleeping, dreaming, and learning

blood vessel contraction
increases heart rate
in what disorders does norepinephrine play a role?
mood disorders, such as manic depression

why SRI therapy should be coupled with norepinephrine therapy for best effects
from where is epinephrine released?
adrenal medulla, via acetylcholine action and in response to exercise and hypoglycemia
what is GLP-1?
glucagon-like peptide-1
what is GIP?
gastric inhibitory polypeptide
what is ghrelin?
gastrointestinal hormone from stomach and pancreas which stimulates hunger by stimulating synthesis of NPY, resulting in the activation of AMPK

from same gene as obestatin
what is obestatin?
gastrointestinal hormone which stimulates satiety (feeling of fullness)

from same gene as ghrelin
counters effects of ghrelin
what hormones are part of the pancreatic polypeptide family?
36aa peptides

pancreatic polypeptide (PP)
protein tyrosine tyrosine (PYY)
neuropeptide tyrosine (NPY)
which of the pancreatic polypeptides are endocrine hormones?

what are the others?
pancreatic polypeptide (PP) and protein tyrosine tyrosine (PYY) are endocrine hormones

neuropeptide tyrosine (NPY) is a neurotransmitter
what is the function of AMPK?
switches a cell from ATP consumption to ATP production
what are the functions of pancreatic polypeptide (PP)?
suppresses glucose-induced insulin secretion

inhibits bicarb and protein secretion from pancreas
what are the functions of protein tyrosine tyrosine (PYY)?
inhibits gastric motility by inhibiting cholinergic neurotransmission

inhibits gastric acid secretion
what are the functions of neuropeptide tyrosine (NPY)?
controls feeding behavior and energy homeostasis

induced by ghrelin

creates desire to eat
what is the function of the renin-angiotensin axis?
effect changes in blood pressure
what stimulates renin to be released? from where?
drop in blood pressure

from juxtaglomerular cells in the kidneys
what is the function of renin?
cleave angiotensinogen to produce angiotensin I
where is angiotensinogen produced?
liver
what is the function of angiotensin converting enzyme (ACE)?
cleave angiotensin I to produce angiotensin II
what are the functions of angiotensin II?
potent vasoconstrictor
increased vasopressin (ADH) release
increased ACTH release
what is the major acute-phase protein made by the liver?
C-reactive protein (CRP)
what are the adipokines (adipocytokines)?
leptin
adiponectin
resistin

(also TNFalpha, IL-6, CRP, PAI-1, MCP-1, visfactin, chemerin, omentin, vaspin, adipsin)
what is the only hormone expressed exclusively by adipocytes?
adiponectin

(other adipokines are released from other cells of the adipose tissue, e.g. macrophages, etc.)
why is visceral adipose tissue especially bad?
the adipokines released from adipose tissue are inflammatory, and if that adipose tissue is visceral, then the organs and vasculature supplying them are affected
what are the functions of leptin?
regulates overall body weight by limiting food intake and increasing energy expenditure

regulates neuroendocrine axis, inflammatory responses, blood pressure, and bone mass
what is the result of leptin or leptin receptor deficiency?
obesity (even with no-fat diet)
why is leptin not the miracle diet drug it was expected to be?
high levels result in abnormally strong immune responses and predisposes individuals to autoimmune phenomena

in obese individuals, there is a barrier which prevents leptin from getting to the relevant portions of the brain
what stimulates the expression and release of adiponectin?
what inhibits the expression and release of adiponectin?
stimulated by insulin

inhibited by TNFalpha
what are the functions of adiponectin?
exerts inflammatory modulation by reducing the production and activity of TNF-alpha and IL-6

stimulate phosphorylation and activation of AMPK
liver - reduces activity of gluconeogenic enzymes & glucose output
muscle - increased glucose uptake, fatty acid oxidation, phosphorylation and inhibition of acetyl-CoA carboxylase
in what patients are levels of adiponectin reduced?
obese individuals
patients with anorexia nervosa
where is AdipoR1 found?
AdipoR2?
AdipoR1 - skeletal muscle
AdipoR2 - liver
what are the key things to remember about adiponectin?
antiinflammatory adipokine
enhances insulin sensitivity
production reduced in obese individuals
phosphorylates & activates AMPK
high levels of adiponectin=high fat metabolism
what are the key points to remember about resistin?
secreted by adipocytes
levels increase with adiposity
induces resistance to insulin
what are the actions of resistin?
induces insulin resistance
decrease hepatic AMPK activity
increase hepatic glucose production
reduced glycogen synthesis
modulates endothelial cell function by increasing VCAM-1 expression
what are the steroid hormones?
adrenal steroids - cortisol, aldosterone, androstenedione

sex hormones - testosterone, progesterone, estradiol
where are the receptors for steroid hormones?
intracellular receptors
(transcription factors)

some are in cytosol and others are in the nucleus
what is the intermediate precursor for all steroid hormones?
pregnenolone (produced directly from cholesterol)
what are the categories of adrenal steroids?
glucocorticoids
mineralocorticoids
androgens
what are the effects of glucocorticoids?
regulate carbohydrate metabolism, immunosuppressive and antiinflammatory
inhibit PLA2
what are the glucocorticoids?
cortisol
corticosterone
what are the effects of mineralocorticoids?
regulate sodium and potassium ion excretion (in addition to other electrolytes)
what are the mineralocorticoids?
aldosterone
what are the effects of androgens?
act similar to male gonadal steroids
what are the adrenal androgens?
androstenedione
DHEA
to what is DHEA rapidly converted?
DHEA-S (sulfated DHEA)
for what is androstenedione a precursor?
testosterone
estradiol
where is aldosterone synthesized?
from progesterone in the zona glomerulosa of adrenal cortex
what are the effects of aldosterone?
increases sodium ion uptake
raises blood pressure and fluid volume
what is the dominant glucocorticoid in humans? the dominant mineralocorticoid?
glucocorticoid - cortisol

mineralocorticoid - aldosterone
where is cortisol synthesized?
from progesterone in the zona fasciculata of the adrenal cortex
what are the effects of cortisol?
elevates blood pressure and sodium ion uptake
involved in stress adaptation
numerous effects on the immune system
how can stress cause insulin resistance?
cortisol increases lipid metabolism in adipose tissue, releasing it into the blood; since elevated lipid levels cause insulin resistance, chronic/prolonged/recurrent stress can lead to prolonged hyperlipidemia and thereby insulin resistance
what hormones are produced in each of the levels of the adrenal cortex (from superficial to deep)?
zona glomerulosa - aldosterone (mineralocorticoids)
zona fasciculata - cortisol, corticosterone (glucocorticoids)
zona reticularis - androstenedione, DHEA (androgens)
what is the primary hormone responsible for male secondary sex characteristics?
testosterone
what is another name for p450c21?
cyp21A2

21-hydroxylase
what is adrenal cortex hypoplasia?
adrenal cortex is not producing as much of the adrenal cortical hormones as it should
what is adrenal cortex hyperplasia?
some aspect of hormone synthesis has run amuck and adrenal cortex is producing too much of its hormones
what are the three types of disorders in adrenal steroidigenesis?
addison disease
cushing syndrome
congenital adrenal hyperplasias
what is addison disease?
lack of adrenal steroid synthesis (hypoplasia)
what are the symptoms of addison disease?
fatigue
weakness
weight loss
skin pigmentation
low blood pressure
nausea
salt cravings
painful muscles and joints
what is cushing syndrome?
adrenal cortex hyperplasia caused by a pituitary tumor
(NOT a congenital adrenal hyperplasia)
what are the symptoms of cushing syndrome?
upper body obesity
excess fat in neck
rounded face
slender arms and legs
fragile, easily bruised skin
weakened bones
high blood pressure
increased thirst, anxiety, depression, and irritability
what are the three clinical forms of congenital adrenal hyperplasias?
salt-losing
simple virilizing
attenuated
what is the most common cause of congenital adrenal hyperplasias?
defect in 21-hydroxylase (CYP21A2)
what is the major feedback inhibitor of ACTH?
cortisol
how do symptoms manifest in the salt-losing form of congenital adrenal hyperplasia?
deficiency in 21-hydroxylase leads to deficiency in glucocorticoids and mineralocorticoids

lack of cortisol drives ACTH release from anterior pituitary

increased 17alpha-hydroxyprogesterone diverted to androgens (causing masculinization)

lack of aldosterone and cortisol drives salt loss
what is the first sign of a congenital adrenal hyperplasia?
ambiguous female genitalia at birth
how are symptoms manifest in the simple virilizing form of congenital adrenal hyperplasia?
21-hydroxylase deficiency not as severe as salt-losing form

aldosterone synthesis compensates for salt loss

ACTH high (because cortisol is not produced in sufficient quantity to inhibit anterior pituitary), which drives excess 17alpha-hydroxyprogesterone to produce androgens, which then masculinize female genitalia
how are symptoms manifest in the attenuated form of congenital adrenal hyperplasia?
21-hydroxylase deficiency is only mild, so there is a small excess in production of androgens
what are the symptoms of the attenuated form of congenital adrenal hyperplasia?
symptoms manifest at puberty

hirsutism
amenorrhea
ovarian cysts
what is hirsutism?
excessive growth of thick dark hair in locations where hair growth in women usually is minimal or absent (e.g. face, chest, areolae, axillae)
what hormone is the primary hormone for secondary sex characteristics in females?
progesterone
which hormones regulate ovarian cycles?
progesterone
estradiol
from where is progesterone secreted?
made directly from pregnenolone and secreted from corpus luteum
what are the actions of progesterone?
responsible for changes in luteal phase of menstrual cycle

differentiation factor for mammary glands
from where is estradiol secreted?
produced in and secreted from ovaries
where is testosterone synthesized?
95% - Leydig cells of testes
5% - adrenal cortex
what is secreted by leydig cells of the testis?
testosterone
dihydrotestosterone
androstenedione
dehydroepiandrosterone (DHEA)

estradiol, estrone, pregnenolone, progesterone, 17alpha-hydroxypregneolone, 17alpha-hydroxyprogesterone
what is dihydrotestosterone?
DHT

a degradation byproduct of testosterone, which is also a potent androgen
what are the functions of testosterone?
differentiation of external and internal male genitals
stimulates skeletal muscle growth
growth of larynx
stimulates pubic, axillary, facial hair
social behavioral changes
what are the two endocrine axes which control testicular function?
hypothalamic - pituitary - leydig cell axis

hypothalamic - pituitary - seminiferous tubule axis
what is the hypothalamic - pituitary - leydig cell axis?
hypothalamus secretes GnRH

GnRH stimulates release of LH by gonadotrophs in anterior pituitary

LH enters Leydig cells and leads to androgen release

androgens (mainly estradiol) feedback inhibit hypothalamus
how does LH cause androgen release?
bind G-protein coupled receptor in Leydig cells which leads to increased cAMP, and then to androgen release
what is the principal inhibitor of GnRH?
estradiol
what is the hypothalamic - pituitary - seminiferous tubule axis?
hypothalamus secretes GnRH

GnRH stimulates release of FSH by gonadotrophs in the anterior pituitary

FSH binds to sertoli cells, and induces production of androgen-binding protein
what is the function of androgen-binding protein?
keeps high concentration of testosterone in seminiferous tubules, increasing spermatogenesis
what is Kleinfelter's syndrome?
XXY males

most common hypogonadism
what is bilateral anorchia?
male (XY) with no distinguishable testicular tissue
what is cryptorchidism?
unilateral or bilateral absence of testes in the scrotum
what is gynecomastia?
unilateral or bilateral breast enlargement in males, caused by imbalance in estrogen/androgen levels
what are the functions of the estrogens?
maturation of female sex characteristics, genital and breast development
growth of endometrial lining
alteration of fat distribution, decrease lipid oxidation, increase TG synthesis
decrease bone resorption by antagonizing parathyroid hormone
what are the functions of progesterone?
glandular development in breast
cyclic glandular development of endometrium
increases body temperature
alters respiratory function
what is the function of androgens in females?
principally testosterone and dihydrotestosterone

normal hair growth

conversion to estrogens
what is the hypothalamic - pituitary - ovarian cell axis?
hypothalamus secretes GnRH

GnRH stimulates release of LH and FSH by gonadotrophs in anterior pituitary

LH induces androstenedione and testosterone synthesis in thecal cells

FSH stimulates aromatase activity in granulosa cells (converting androgens to estrogens)
where are the estrogens from thecal cells secreted?

where are the estrogens from granulosa cells secreted?
thecal cells secrete estrogens into circulation

granulosa cells secrete estrogens into follicular fluid
what is amenorrhea?
lack of menstruation

(could have physical or hormonal causes)
what is gonadal agenesis?
female hypogonadism
what is Turner's syndrome?
gonadal dysgenesis due to 45,X karyotype