Overview Flashcards
Murphy readers
a substance produced by cells which has a specific regulatory effect on the activity of a specific organ/ organs at a distant site
hormone
a type of extracellular signaling in which the secreting cell and target cell are the same
autorcrine
a type of extracellular signaling in which the signaling molecule binds to its receptor on nearby cells and affects their function
paracrine
a type of extracellular signaling in which a hormone that has a specific effect on another organ at a distant site is secreted into the blood
endocrine
-of or pertaining to nourishment or growth
trophic
What are the three structures that compose the pituitary gland?
pars distalis (adenohypophysis)
pars intermedia
pars nervosa (neurohypophysis)
The pars distalis (PD) is the largest part of the pituitary gland and secrets the most trophic hormones. What does the PD produce?
LH
FSH
ACTH/MSH
GH
TSH
prolactin
The pars intermedia (PI) forms the junction between the pars distalis and neuohypophysis. What hormones dose it produce?
ACTH
MSH
**in dogs and horses
The neurohyophysis (PN) is an extension of the overlying hypothalamus. Which hormones does it secrete?
ADH
oxytocin (produced, but not made here)
What structure separates the pars distalis from the intermedia?
Rathke’s pouch
**in most species except the horse
What are the 3 endocrine cell populations, located in the pars distalis and pars intermedia, that secrete the pituitary hormones? How can they be used to differentiate between the distalis and intermedia?
acidophils, basophils, chromophobes
the pars intermedia has more prominent basophils and lacks acidophils, generally
a congenital syndrome that is most commonly identified in GSDs that occurs due to the failure of oral ectoderm to differentiate and mature into trophic hormone-secreting cells of the pars distalis
most consistent feature results from a congenital growth hormone deficiency; however, secretory production of TSH, prolactin, FSH and LH have also been found to be drastically reduced
juvenile panhypopituitarism (pituitary drwarfism)
***other affected dog breeds include Spitz, Toy Pinschers and Karelian Bear dogs
T/F: eACTH production is often low in circulation in dogs with pituitary dwarfism.
F - both plasma ACTH and cortisol levels generally remain WNL
What 2 hormones are secreted by the posterior pituitary? What is the most clinically relevant syndrome due to a lesion in the neurohypophysis?
ADH, oxytocin
Diabetes insipidus (neurogenic diabetes insipidus)
T/F: Tumors of the pars nervosa are very rare in comparison to the pars distalis and intermedia.
T- Ex. pituicytoma, a type of astrocytoma
