Pituitary Gland Flashcards
(44 cards)
what’s the other name for the pituitary gland? where is it normally located?
hypophysis
sella turcica, a depression in the sphenoid bone
pituitary gland has a close anatomic relationship to the _____, _____, and ______.
optic chiasm, hypothalamus, brain
what are the two components of the pituitary gland?
- adenohypophysis (anterior pituitary)
- neurohypophysis (posterior pituitary)
what are the two components of the adenohypophysis?
- pars distalis
- pars intermedia
what does the pars distalis do?
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)
what does the pars intermedia do?
melanotrophs = predominant cell (POMC –> MSH)
ACTH production in dogs
what does the neurohypophysis do?
oxytocin, ADH
neurons originate in the hypothalamus
what disorder of the neurohypophysis do we have to know?
diabetes insipidus
what are the two categories of disorders of the adenohypophysis, and what falls under each category?
- hypopituitarism
- aplasia & prolonged gestation
- pituitary cysts (Pituitary dwarfism)
- non-functional tumors that destroy the pituitary - hyperpituitarism –> functional (hormone-secreting) tumors
- corticotroph (ACTH-secreting) adenomas
- melanotroph adenomas of the pars intermedia
- somatotroph adenomas
why does hypopituitarism cause aplasia and prolonged gestation?
parturition requires intact hypothalamic-pituitary-adrenocortical axis
in regards to aplasia and prolonged gestation, what is an example of a cause of hypopituitarism and what does it result in?
Veratrum californicum (skunk cabbage)
ingestion day 14 of gestation causes a neural tube defect
numerous craniofacial defects (cyclopia)
aplasia or malformation of the adenohypophysis
poor little dude was born this way! what might his mother have done during gestation to make him like this?
ate Veratrum californicum on day 14 of gestation
what causes a pituitary cyst?
failure of the oropharyngeal ectoderm of Rathke’s pouch to differentiate into the pars distalis
what does a pituitary cyst cause?
juvenile panhypopituitarism (pituitary dwarfism)
what breed is predisposed to pituitary cysts and what does it do in that breed?
German shepherds (autosomal recessive)
failure to grow, retention of puppy coat
hypoadrenocorticism, hypothyroidism
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?
juvenile panhypopituitarism/pituitary dwarfism caused by a pituitary cyst
what’s the lesion?
pituitary cyst
nonfunctional pituitary neoplasms most often occur in what species?
dogs and cats
what are the clinical signs of nonfunctional pituitary neoplasms due to?
hypo function of pituitary and diminished target organ function
CNS compression
what are the clinical signs of a nonfunctional pituitary neoplasm that is caused by CNS compression?
weakness, ataxia, blindness, diabetes insipidus
what are the clinical signs of a nonfunctional pituitary neoplasm that is caused by hypo function of pituitary and diminished target organ function?
hypothyroidism
hypoadrenocorticism
gonadal atrophy in intact animals
what’s the lesion
nonfunctional pituitary adenoma
Corticotroph, or adrenocorticotropic hormone-secreting adenomas are common in what species?
dogs, increasingly cats
where do corticotroph or ACTH-secreting adenomas occur?
in the corticotroph cells of pars distalis or intermedia in dogs
