Intro stuff 171 and 172 Flashcards by Emily Zaniker

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

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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

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Which type of secretion is this:

TGF-beta acts locally on cell divisionof nearby cells

paracrine

acts on surrounding cells/tissues

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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

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What are the three major classes of hormones?

peptides, steroid derivatives, amino acid derivatives

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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.

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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.

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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.

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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

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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)

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What hormones are produced by the anterior pituitary (6)?

growth hormone
prolactin
leutinizing hormone
follicle stimulating hormone
adrenocorticotropic hormone
thyroid stimulating hormone

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What is the effect of the following hypothalamic hormones on growth hormone release:

GHRH (+ or -)

somatostatin (+ or -)

GHRH (+)

somatostatin (-)

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What is the effect of the following hypothalamic hormones on prolactin release:

dopamine (+ or -)

VIP (+ or -)

dopamine (-)

VIP (+)

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What is the effect of gonadotropin releasing hormone on:

lutenizing hormone (+ or -)

follicle stimulating hormone (+ or -)

lutenizing hormone (+)

follicle stimulating hormone (+)

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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

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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

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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

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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

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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.

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Glucagon __________ hepatic glucose production.

Glucagon stimulates hepatic glucose production.

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Where is epinephrine and norepinephrine produced?

sympathetic nervous system and adrenal medulla

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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

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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 ## Footnote *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 ## Footnote *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 ## Footnote *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 ## Footnote *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 ## Footnote * 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 ## Footnote * 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*