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GH is released from the ________ in response to GHRH from the _________, causing the release of _______.
anterior pituitary; hypothalamus; IGF-I
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Prolactin is released from the _______ in response to ________ from the hypothalamus.
anterior pituitary; TRH
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ACTH is released from the ________ in response to ______ release from the hypothalamus; it affects the _______, causing it to release _______.
anterior pituitary; CRH; adrenal gland; hyrocortisone
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TSH is released from the _________ in response to _______ from the hypothalamus; it affects the _______, causing it to release _______.
anterior pituitary; TRH; thyroid gland; thyroxine
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LH/FSH are released from the __________ in response to ________ released from the hypothalamus.
anterior pituitary; GnRH
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Vasopressin is released from the _________ in response to _______ from the hypothalamus; it affects the ________, causing...
posterior pituitary; vasopressin; kidney; decrease in urine volume
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Oxytocin is released from the ________ in response to _______ from the hypothalamus.
posterior pituitary; oxytocin
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The pars nervosa differentiates from _________.
nervous tissue
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The pars distalis differentiates from _______.
ectoderm
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The pars intermedia differentiates from ____________.
ectoderm/nerve junction
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In what species is the pars intermedia more developed/important?
species that seasonally change hair coat or color (ex. horses, frogs)
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What hormones are in the somatotrophin-lactogen group?
prolactin, growth hormone
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What hormones are in the two subunit group?
LH, FSH, TSH
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What hormones are gonadotropins?
LH and FSH
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When POMC is in the pars intermedia, it is cleaved to _________; when it is in the pars distalis, it is cleaved to ________.
MSH; ACTH
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Growth hormone aka=
somatotropin
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GH is secreted from the __(2)__ in endocrine concentrations.
placenta and pituitary
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Describe the negative feedback mechanism of GH.
GH inhibits the release of hypothalamic GHRH; IGF-I released in response to GH stimulates the release of somatostatin, which inhibits pituitary release of GH
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An increase in glucose causes a(n) ________ in GH.
decrease
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An increase in amino acid conc. causes a(n) ______ in GH.
increase
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An increase in exercise causes a(n) ________ in GH.
increase
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An increase in sleep causes a(n) ________ in GH.
increase
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An increase in stress causes a(n) ________ in GH.
decrease
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An increase in ADH causes a(n) ________ in GH.
increase
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An increase in ghrelin causes a(n) ________ in GH.
increase
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GH secretion is maximal during ________, especially in _________.
sleep; growing stock
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What is unique about GH release?
it occurs in short bursts
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GH has direct actions via ____________; it has indirect actions via ___________.
GH receptors on target cells; IGF-I (insulin-like growth factor I)
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What are the biological actions of GH?
bone growth, protein, carb, and fat metabolism, lactation
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GH antagonizes _________.
insulin
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BST.
bovine somatotropin- milk production
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_______ inhibits prolactin secretion.
Dopamine
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_________ stimulates prolactin secretion.
Thyrotropin-releasing hormone (TRH)
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__________ drugs increase milk production by disinhibiting prolactin.
Dopamine antagonistic
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Other than the pituitary, what is the other source of prolactin?
placenta during pregnancy
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Describe the feedback regulation of prolactin.
prl inhibits its own synthesis and secretion by affecting the pituitary and by causing dopamine release from the hypothalamus
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An increase in estrogen causes a(n) __________ in prolactin.
increase
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Suckling of young causes a(n) _________ in prolactin.
increase
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Pregnancy causes a(n) _________ in prolactin.
decrease
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Sleep causes a(n) __________ in prolactin.
increase
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What are the biological actions of prolactin? (3)
mammary growth, lactation, maintenance of CL (rats), paternal behavior
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_________ stimulates release of TSH (thyroid stimulating hormone) from the _________.
Thyrotropin releasing hormone (TRH); anterior pituitary
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________ decreases TSH release.
Somatostatin
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Describe the negative feedback regulation of TSH.
TSH causes release of T3 and T4, which in turn reduce secretion of TRH from the hypothalamus AND TSH secretion from the anterior pituitary
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Cold stress causes a(n) ________ in TSH.
increases
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Estrogen causes a(n) ________ in TSH.
increase
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Glucocorticoids cause a(n) ________ in TSH.
decrease
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GH causes a(n) ________ in TSH.
decrease
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What are the biological actions of TSH?
stimulates synthesis and secretion of thyroid hormone in the thyroid
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Dog pars intermedia tumors make _______; horse oars intermedia tumors make ________.
ACTH; MSH
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CRH from the _________ stimulates ______ synthesis, which is cleaved to ________ in the ________ and secreted.
hypothalamus; POMC; ACTH; anterior pituitary
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Describe feedback regulation of ACTH.
ACTH stimulates glucocorticoids that inhibit CRH release from the hypothalamus and ACTH from the pituitary
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What are the biological actions of ACTH?
stimulates synthesis and secretion of glucocorticoids from the adrenal
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What are the biological actions of MSH?
stimulates pigment in melanocytes
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What are the biological actions of beta-LPH (which originates from POMC)?
stimulates lipolysis in fat cells
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Excessive ACTH.
cushings dz
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Deficient ACTH.
addisons dz
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Pituitary dwarfism is caused by ______________, which leads to failure of __________.
juvenile-onset panhypopituitarism; development of the adenohypophysis
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What are the clinical signs of juvenile onset hypopituitarism? (5)
failure to attain somatic maturation (dwarfism), retention of juvenile hair coat, alopecia, shrill bark, skin lesions
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With juvenile onset panhypopituitarism, there is deficiency of __(4)__ and subnormal secretion of __(3)__.
GH, TSH, ACTH, GTH [trophic hormones]; thyroxine, cortisol, sex steroids [target organ hormones]
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With juvenile onset panhypopituitarism, there is lack of ______ and subsequently ________, leading to small stature.
GH (somatotrophin); IGF-1
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How does stress cause alopecia?
stress decreases GH--> GH is required for hair growth
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What gene is deleted in dogs, leading to pituitary dwarfism?
LHX3
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How is hypothyroidism released to panhypopituitarism in adult animals?
chronic hypothyroid--> atherosclerosis of internal carotid--> pituitary ischemia--> secondary pituitary ischemic necrosis--> panhypopituitarism
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How is hypophysitis related to panhypopituitarism?
inflammation/swelling of pituitary--> pituitary surrounded by bone and tissue has no where to go--> necrosis--> panhypopituitarism
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What are the pathogenic mechanisms of hypophysitis? (6)
meningitis, encephalitis, otitis media, sinusitis, osteomyelitis, septicemia (indirect)
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Describe the features of pituitary adenomas. (4)
benign, slow growth, compression of adjacent structures, extension along lines of least resistance
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What are the 2 types of pituitary adenomas?
functional (hormone-producing), non-functional
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Are functional or non-functional pituitary adenomas more difficult to diagnose?
non-functional are more difficult to diagnose and worse prognosis because they don't show clinical signs until they are huge
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A functional chromophobe adenoma derives from ___________ and is located in the _____________; it causes hypersecretion of _________, leading to __________; the syndrome associated with this is ____________.
pituitary corticotrophs; pars distalis/intermedia; ACTH; adrenal cortex hyperplasia; Cushing's disease
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A non-function pituitary adenoma is a potential cause of ___________; it causes it's worst effects due to being a ___________.
adult-onset panhypopituitarism; space-occupying lesion
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What are the functional disturbances associated with adult-onset panhypopituitarism? (5)
gonadal atrophy, thyroid follicular cellular atrophy, adrenal cortical atrophy, hypoglycemia, PU/PD (no ADH)
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What are the clinical signs of pituitary chromophobe adenoma in a parakeet? (6)
impaired vision, exophthalmos, disturbance in balance, seizures, polydipsia, diarrhea
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PPID in horses is a disease of ______.
age
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Par intermedia tumors of horses make...
MSH, endorphins (affected horses are more chill than normal)
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Clinical signs of PPID in horses.
failure to shed haircoat, long/matted hair
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Describe juvenile-onset hyperfunction of STH-secreting acidophils. What causes it? (2)
gigantism; somatotroph hyperplasia, somatotroph adenoma
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Describe adult-onset of growth-hormone excess. What causes it in dogs? (3)
acromegaly;acidophil adenoma, iatrogenic GH (progestagen for estrus control), prolonged luteal phase (luteal cysts)
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What are the clinical signs of acromegaly in dogs? (7)
excessive skin folds, abnormal hair growth, respiratory stridor (increased soft tissue), abdominal enlargement, PU/PD, expansion of interdental space, fatigue
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Describe the diabetogenic action of GH excess. (5)
down regulate insulin receptors, progressive hyperglycemia, glycosuria, beta cell hyperplasia, insulin-resistance
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Feline acromegaly is caused by __________.
acidophil adenom (somatotrophs of pars distalis)
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How do you diagnose acidophil adenoma in cats?
measure IGF-1
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Describe a prolactinoma in a rat. (2)
cystic hyperplasia, mammary gland development
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Craniopharyngioma occurs in _____ animals; it leads to... (3) [rare]
young; pituitary dwarfism; panhypopituitarism; CNS deficits
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Diabetes insipidus is a syndrome resulting from deficient _________, resulting in ____________.
ADH from pars nervosa; failure of active water resorption
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