Flashcards in Ex 4 - Pituitary and Adrenal Glands Deck (20):
What are hormones comprised of?
Proteins, aa derivatives, or steroids
Describe hormone release
1. Immediate release (preformed substrate)
2. Stimulation of synthesis and delayed release
Describe hormones as controlling elements
The hormone that is produced acts as its own negative feedback loop
Describe hormones as controlled variables
Secondary hormones feedback to primary endocrine organs to shut down production of 'primary' hormones
What bone is poorly formed in the head of the horse?
(allows for compression of the overlying structures)
Sella turcica bone
Name 3 regions in the pituitary gland
1. Pars nervosa
2. Pars intermedia
3. Pars distalis
What are the 3 cells of the pars distalis?
- Growth hormone (major counter regulatory hormone to insulin)
- lack secretory content
What is released from the pars intermedia?
Melanocyte-stimulating hormone (MSH)
*important in the dopamine regulatory pathway and pathogenies of equine PPID
What are the 3 zones of the adrenal cortex (outer to inner)? and what hormones do each release?
1. Zona glomerulosa = salt
- mineralocorticoids (e.g. aldosterone)
2. Zona fasciculata = sugar
- glucocorticoids (e.g. cortisol)
3. Zona reticularis = sex
- androgens (e.g. DHA)
*Remember GFR = layers
What stimulates the release of ADH?
Hyperosmolarity and hypovolemia
ADH and Nephrogenic diabetes insipidus
Kidney's don't respond to ADH
Mineralcorticoid regulation (aldosterone)
Release stimulated by falling or rising BP and high K+
Promotes salt retention and promotes RAAS activation
What is the primary function of Gucocorticoids?
induce hepatic gluconeogenesis
- inhibits glucose uptake and metabolism in peripheral tissues
- synergies with glucagon actions
- directly increases lipolysis and redistributes fats
What are some other functions of glucocorticoids?
- promotes protein catabolism
- promotes diuresis (increases GFR)
- prevents arachidonic acid metabolism
- surpasses lymphocyte and MO fxn
How do animals with glucocorticoid abnormalities present?
1. Pot belly appearance
3. PU/PD (ADH is inhibited)
4. Secondary infections (immune system suppressed)
Four major mechanisms of Endocrine dz
1. Primary hyperfunction (most common)
- commonly caused by neoplasia
2. Primary hypofunction
3. Secondary hyper function
4. Secondary hypo function
- loss of a trophic stimulus leads to a loss of stimulation/feedback & atrophy
- target tissue is unable to respond to hormone --> endocrine organ works harder --> eventually fails
Almost always due to some proliferative disease
Usually a degenerative or hypo plastic process
How do we classify lesions?
- neoplasia (functional)
- neoplasia (non-functional)