Intro stuff 171 and 172 Flashcards
Differentiate endocrine, exocrine, paracrine, autocrine.
where are they made and where do they go
Endocrine –> made in a gland, acts on distant target via circulation
Exocrine –> made in a gland, released locally on tissue via a duct
Paracrine –> made by cells, released into extracellular space and acts locally on nearby cells
Autocrine –> made by gland, acts on gland itself
Which type of secretion is this:
trypsin, an enzyme released by pancreatic exocrine cells, is released into pancreatic ducts and ends up in the small intestine to help break down ingested proteins
exocrine secretion
acts locally on tissue at the end of the duct
Which type of secretion is this:
TGF-beta acts locally on cell divisionof nearby cells
paracrine
acts on surrounding cells/tissues
Which type of secretion is this:
IL-1 binds on the gland that produces it in order to modulate gland function
autocrine
binds on its own gland
What are the three major classes of hormones?
peptides, steroid derivatives, amino acid derivatives
Peptide hormones are initially synthesized as _________ and are __________ to active form. They bind ______________ receptors.
Peptide hormones are initially synthesized as larger peptides and are cleaved to active form. They bind extracellular membrane-bound receptors.
Steroid hormones are initially derived from __________. They bind __________ with translocation to the __________ for _____________.
Steroid hormones are initially derived from cholesterol. They bind cytoplasmic receptors with translocation to the nucleus for DNA binding.
Amino Acid hormones are derived from __________. They bind to _________ receptors where they ___________ and bind to ___________.
Amino Acid hormones are derived from tyrosine. They bind to extracellular membrane-bound receptors where they cross the cell membrane and bind to nuclear receptors.
What are negative feedback loops? Positive feedback?
negative feedback –> an end product of a reaction acts on an earlier stage of the reaction to downregulate it
positive feedback –> an end product of a reaction acts on an earlier stage of the reaction to upregulate it
What is autonomy in the context of endocrine tumors?
endocrine tumors lose some, but not all, of their feedback control
ex. an endocrine tumor may not respond to signals that should downregulate hormone production, but may still respond to signals that upregulate it (and make the tumor worse)
What hormones are produced by the anterior pituitary (6)?
- growth hormone
- prolactin
- leutinizing hormone
- follicle stimulating hormone
- adrenocorticotropic hormone
- thyroid stimulating hormone
What is the effect of the following hypothalamic hormones on growth hormone release:
GHRH (+ or -)
somatostatin (+ or -)
GHRH (+)
somatostatin (-)
What is the effect of the following hypothalamic hormones on prolactin release:
dopamine (+ or -)
VIP (+ or -)
dopamine (-)
VIP (+)
What is the effect of gonadotropin releasing hormone on:
lutenizing hormone (+ or -)
follicle stimulating hormone (+ or -)
lutenizing hormone (+)
follicle stimulating hormone (+)
Tumors of cells producing which hormones correspond to the following syndromes:
a) acromegaly
b) Cushing’s disease
c) prolactinoma
d) hyperthyroidism
a) acromegaly –> growth hormone
b) Cushing’s disease –> ACTH
c) prolactinoma –> prolactin
d) hyperthyroidism –> thyroid stimulating hormone
What hormones are produced by the posterior pituitary (2)? What do they do?
vasopressin: controls water reabsorption by distal tubule
oxytocin: responsible for milk let-down in the puerperium
What subclasses of hormones are produced in the adrenal cortex (3)? What do they do?
glucocorticoids (ex. cortisol) –> withstand stress, increase glucose
mineralocorticoids (ex. aldosterone) –> Na retention, BP elevation
androgens –> causes virilization in women
What hormone is produced by parathyroid glands (1)? What does it do?
parathyroid hormone (made by Chief cells)
stimulates calcium resorption from bone, calcium reabsorption by kidneys, calcium uptake from intestines
Insulin regulates blood glucose levels by stimulating ________ by tissues and inhibiting hepatic __________.
Insulin regulates blood glucose levels by stimulating glucose uptake by tissues and inhibiting hepatic glucose production.
Glucagon __________ hepatic glucose production.
Glucagon stimulates hepatic glucose production.
Where is epinephrine and norepinephrine produced?
sympathetic nervous system and adrenal medulla
What type of gland is a sweat gland?
exocrine gland
sweat glands pour out their secretions onto the surface of the skin and not into the blood, which would have made them endocrine glands
Which of the following hormones is closed in structure to oxytocin?
a) insulin
b) prolactin
c) vasopressin
d) thyroine
e) estradiol
c) vasopressin
two posterior pituitary hormones, vasopressin and oxytocin, are very similar and differ by just two amino acids
Which hormone is secreted in excess in a patient with Cushing’s disease?
ACTH
secreted in excess in patients with Cushing’s disease, leading to hypercortisolism
Which of the following conditions is most likely in the US?
a) hyperparathyroidism
b) type 2 diabetes mellitus
c) obesity
d) osteoporosis
e) Grave’s disease
c) obesity
present in over 35% of the US population
In a patient with Graves’ disease, which is due to an antibody stimulating the TSH receptor, which pattern of hormones would you expect to find?
a) TSH high, free T4 high, T3 high
b) TSH low, free T4 high, T3 high
c) TSH normal, free T4 high, T3 high
d) TSH normal, free T4 high, T3 low
b) TSH low, free T4 high, T3 high
antibody stimulates thyroid to make more thyroid hormones (T3 and T4), which leads to downregulation of TSH via negative feedback
Hypophysiotrophic neurons localized in ________ project to the _________ to secrete ___________ into the _________.
Hypophysiotrophic neurons localized in hypothalamic nuclei project to the median eminence to secrete peptide and bioamine releasing and inhibiting hormones into the proximal end of the hypothalamic-pituitary portal vessels.
Neurohypophysial neurons originate in the ________ and _______, traverse the _________, and release _______ and ________ from nerve endings in the __________.
Neurohypophysial neurons originate in the supraoptic and paraventricular nuclei, traverse the hypothalamic-pituitary stalk, and release vasopressin and oxytocin from nerve endings in the posterior pituitary.
Which pituitary hormone is under tonic inhibition by the hypothalamus?
prolactin
all others are stimulated –> cutting the pituitary stalk leads to hypopituitarism, but hyperprolactinemia
Where does the anterior lobe of the pituitary derive from?
Rathke’s pouch, invagination of the oral ectoderm
Where does the posterior lobe of the pituitary derive from?
evagination of the neural ectoderm of the ventral diencephalon
What cells secrete prolactin?
pituitary lactotrophs in the anterior pituitary
What is the primary action of prolactin?
stimulates breast epithelium to proliferate and induces milk production in puerperium
Prolactin is under continuous ________ from the hypothalalmus by ________.
Prolactin is under continuous inhibition from the hypothalalmus by dopamine.
Which peptides and hormones lead to increased stimulation of prolactin?
peptides: TRH, VIP but only when dopamine is low
hormone: estrogen (during pregnancy)
What cell secretes growth hormone?
somatotrophs of anterior pituitary
What is the primary action of growth hormone?
linear growth at growth plates of bones
increases osteoclast differentiation/activity, osteoblast activity, and bone mass
Why don’t people continue getting taller forever?
growth hormone levels gradually decrease with age, and later actions are mostly related to maintaining lean body mass and inhibiting fat
What is the relationship between insulin-like growth factor I and growth hormone?
they both lead to growth, negatively regulates growth hormone
What cells produce thyrotropin?
thyrotrophs in anterior pituitary
What is the structure of thyrotropin (TSH)? What is its effect on thyroid function?
glycoprotein heterodimer (alpha and beta subunits)
TSH stimulates thyroid function (T3 and T4)
What are the negative regulators of thyrotropin (TSH)?
somatostatin
elevated T3 and T4 levels (negative feedback loop)
What cells produce FSH and LH?
gonadotrophs in anterior pituitary
What is the effect of FSH on the ovaries? Testes?
ovaries: binds receptors on granulosa cells, leading to estrogen synthesis and follicle growth
testes: binds receptors on sertoli cells, leading to spermatogenesis and inhibin-related proteins
FSH secretion is stimulated by ________ and inhibited by _________.
FSH secretion is stimulated by GnRH and inhibited by inhibin.
What is the effect of LH on the ovaries? Testes?
Ovary: binds theca cells to stimulate production of androgens and steroid precursors
Testes: bind receptors on leydig cells to stimulate testosterone production
What is ACTH derived from? Where is the precursor produced?
POMC
POMC is produced in brain neurons
ACTH stimulates adrenal cortex to produce ____________.
ACTH stimulates adrenal cortex to produce cortisol and adrenal androgens.
Where are vasopressin and oxytocin synthesized?
magnocellular neurons in supraoptic and paraventricular nuclei of hypothalamus –> transported to the posterior pituitary
What is the function of vasopressin?
binds receptors in renal collecting ducts and making them permeable to water –> water is reabsorbed from the urine back to the blood to maintain serum osmolality
What are the major controllers of vasopressin secretion?
osmoreceptors in the hypothalamus (hyperosmolality = stimulates release, hypoosmolality = suppresses release)
baroreceptors in chest (overrides osmotic regulation in severe cases of blood loss)
neural input (in response to pain, stress, medications)
Serum sodum reflects serum osmolality and is controlled only by _________, which is controlled by _______________.
Serum sodum reflects serum osmolality and is controlled only by water balance, which is controlled by vasopressin and thirst.
What is the function of oxytocin? What are triggers of its release?
binds receptors in breast leading to contraction of myoepithelium and ejection of milk
release stimulated by suckling or vaginal stretch during delivery
Which pituitary hormone has the strongest diurnal rhythm?
ACTH
ACTH and cortisol have marked diurnal variation –> lowest levels at midnight and highest in the morning
Which pituitary hormone is tonically suppressed by the hypothalamus?
a) ACTH
b) TSH
c) GH
d) PRL
e) Oxytocin
d) PRL
- prolactin is tonically inhibited by dopamine, which is released into the hypothalamic-pituitary portal vessels where it travels down to act on lactotrophs*
- all other pituitary hormones are tonically stimulated*
A patient is ill and becomes severely dehydrated and hypotensive but is able to drink water. What will his serum sodium levels be?
a) increased
b) decreased
c) unchanged
b) decreased
- severe volume loss and hypotension stimulates vasopressin release, leading to water reabsorption*
- the fact that he can drink water would decrease serum osmolality (usually leading to less water retention), but in this case the volume loss overrides osmolality status*
