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425 - sys path > Pituitary Gland > Flashcards

Pituitary Gland Flashcards

1
Q

what’s the other name for the pituitary gland? where is it normally located?

A

hypophysis
sella turcica, a depression in the sphenoid bone

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2
Q

pituitary gland has a close anatomic relationship to the _____, _____, and ______.

A

optic chiasm, hypothalamus, brain

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3
Q

what are the two components of the pituitary gland?

A
  1. adenohypophysis (anterior pituitary)
  2. neurohypophysis (posterior pituitary)
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4
Q

what are the two components of the adenohypophysis?

A
  1. pars distalis
  2. pars intermedia
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5
Q

what does the pars distalis do?

A

variety of cells that produce trophic factors
each cell type is under the control of a releasing hormone from the hypothalamus

acidophils (GH, PRL), basophils (TSH, FSH, LH), chromophobes (ACTH)

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6
Q

what does the pars intermedia do?

A

melanotrophs = predominant cell (POMC –> MSH)
ACTH production in dogs

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7
Q

what does the neurohypophysis do?

A

oxytocin, ADH
neurons originate in the hypothalamus

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8
Q

what disorder of the neurohypophysis do we have to know?

A

diabetes insipidus

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9
Q

what are the two categories of disorders of the adenohypophysis, and what falls under each category?

A
  1. hypopituitarism
    - aplasia & prolonged gestation
    - pituitary cysts (Pituitary dwarfism)
    - non-functional tumors that destroy the pituitary
  2. hyperpituitarism –> functional (hormone-secreting) tumors
    - corticotroph (ACTH-secreting) adenomas
    - melanotroph adenomas of the pars intermedia
    - somatotroph adenomas
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10
Q

why does hypopituitarism cause aplasia and prolonged gestation?

A

parturition requires intact hypothalamic-pituitary-adrenocortical axis

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11
Q

in regards to aplasia and prolonged gestation, what is an example of a cause of hypopituitarism and what does it result in?

A

Veratrum californicum (skunk cabbage)
ingestion day 14 of gestation causes a neural tube defect
numerous craniofacial defects (cyclopia)
aplasia or malformation of the adenohypophysis

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12
Q

poor little dude was born this way! what might his mother have done during gestation to make him like this?

A

ate Veratrum californicum on day 14 of gestation

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13
Q

what causes a pituitary cyst?

A

failure of the oropharyngeal ectoderm of Rathke’s pouch to differentiate into the pars distalis

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14
Q

what does a pituitary cyst cause?

A

juvenile panhypopituitarism (pituitary dwarfism)

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15
Q

what breed is predisposed to pituitary cysts and what does it do in that breed?

A

German shepherds (autosomal recessive)

failure to grow, retention of puppy coat
hypoadrenocorticism, hypothyroidism

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16
Q

the dog in the back is normal and the dog in the front is abnormal. they are from the same litter. what might be going on?

A

juvenile panhypopituitarism/pituitary dwarfism caused by a pituitary cyst

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17
Q

what’s the lesion?

A

pituitary cyst

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18
Q

nonfunctional pituitary neoplasms most often occur in what species?

A

dogs and cats

19
Q

what are the clinical signs of nonfunctional pituitary neoplasms due to?

A

hypo function of pituitary and diminished target organ function

CNS compression

20
Q

what are the clinical signs of a nonfunctional pituitary neoplasm that is caused by CNS compression?

A

weakness, ataxia, blindness, diabetes insipidus

21
Q

what are the clinical signs of a nonfunctional pituitary neoplasm that is caused by hypo function of pituitary and diminished target organ function?

A

hypothyroidism
hypoadrenocorticism
gonadal atrophy in intact animals

22
Q

what’s the lesion

A

nonfunctional pituitary adenoma

23
Q

Corticotroph, or adrenocorticotropic hormone-secreting adenomas are common in what species?

A

dogs, increasingly cats

24
Q

where do corticotroph or ACTH-secreting adenomas occur?

A

in the corticotroph cells of pars distalis or intermedia in dogs

25
Q

corticotroph or ACTH-secreting adenomas cause what clinical syndrome? is this common?

A

hyperadrenocorticism (Cushing’s disease)
yes common - 85-90% of HAC due to pituitary tumors

26
Q

what are the gross lesions of corticotroph or ACTH-secreting adenomas?

A

bilateral adrenocortical hypertrophy/hyperplasia (zona fasiculata and zona reticularis)

27
Q

what’s the lesion?

A

corticotroph or ACTH-secreting adenoma

28
Q

what is the most common pituitary tumor of horses?

A

melanotroph adenoma of the pars intermedia

29
Q

what clinical syndrome does a melanotroph adenoma of the pars intermedia cause?

A

pituitary pars intermedia dysfunction (PPID)

30
Q

true or false: PPID is the same as Cushing’s disease of horses

A

FALSE!

31
Q

melanotroph adenomas of the pars intermedia are ____ tumors, meaning they cause ____ production of POMC and its derivatives.

A

functional, excessive

32
Q

the clinical syndrome caused by melanotroph adenomas of the pars intermedia is mainly the result of what?

A

hypothalamic/neurohypopheal dysfunction

33
Q

tell me some clinical signs of PPID in horses. you need to know the first one for sure.

A

hypertrichosis
polyphagia
hyperglycemia/glucosuria
PU/PD
weight loss of abnormal distribution of fat
intermittent hyperpyrexia
hyperhidrosis
laminitis

34
Q

this is your horse Gordon. What is causing this clinical sign?

A

melanotroph adenoma of the pars intermedia causing pituitary pars intermedia dysfunction (PPID)

35
Q

this is a horse skull. what is the lesion?

A

melanotroph adenoma of the pars intermedia

36
Q

somatotroph adenomas are primarily in what species?

A

cats

37
Q

what is acromegaly?

A

hyper secretion of growth hormone (GH) aka somatotrophin

38
Q

true or false: somatotroph adenomas cause acromegaly

A

true

39
Q

tell me how a somatotroph adenoma causes diabetes mellitus

A
  1. somatotroph adenoma
  2. hypersecertion of GH
  3. increased IGF-1 secretion by liver
  4. proliferation of ST and bony tissues AND insulin-resistant diabetes mellitus
40
Q

feline hypersomatotropism caused by somatotroph adenomas can result in what clinical signs?

A

broad face, inferior prognathia, clubbed feet, plantigrade stance

41
Q

what are the two forms of diabetes insipidus?

A
  1. hypophyseal or central form
  2. nephrogenic form
42
Q

what is the hypophyseal or central form of diabetes insipidus ?

A

inadequate production of ADH

compression/destruction of the neurohypophysis or hypothalamus

43
Q

what is the nephrogenic form of diabetes insipidus?

A

inability of target cells in kidney to respond to normal to increased levels of ADH

44
Q

diabetes insipidus causes what important clinical sign?

A

inability to concentrate urine

produce large vols of dilute urine, PU/PD

425 - sys path (38 decks)

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