Another term for pituitary gland.
Name the parts of the Hypophysis (Pituitary Gland).
- Anterior Pituitary (adenohypophysis)
- Intermediate lobe (pars intermedius)
- Posterior Pituitary (neurohypophysis)
What is the adenohypophysis derived from?
Rathke's Pouch (pharynx)
What is the Neurohypophysis derived from?
hypothalamus (neural tissue)
Name the 6 hormones secreted by the Anterior Pituitary. (All protein type hormones)
- 1. Growth hormone (GH)
- 2. Adrenocorticotropin (ACTH)
- 3. Thyrotropin (thyroid stimulating hormone)(TSH)
- 4. Luteinizing hormone (LH)
- 5. Follicle stimulating hormone (FSH)
- 6. Prolactin
What does GH stimulate?
What does Adrenocorticotropin (ACTH) stimulate?
- corticol secretion from adrenal cortex.
- made by the anterior pituitary to signal adrenal cortex.
What does Thyrotropin (TSH) stimulate?
- Thyroid hormone secretion from thyroid gland.
- Made by anterior pituitary gland.
What does Luteinizing hormone (LH) stimulate?
- testosterone secretion in male
- ovulation and luteal function in female
What does follicle stimulation hormone (FSH) stimulate?
regulates follicular growth in female
What does prolactin stimulate?
mammary development and function.
What 2 hormones are secreted by the Neurohypophysis?
- 1. Anti-diuretic hormone (Vasopressin)(ADH)
- 2. Oxytocin
Where are ADH and oxytocin made?
The hypothalamus by the parventricular nucleus and the supraoptic nucleus.
What does ADH (vasopressin) stimulate?
causes water conservation
What does oxytocin stimulate?
- expulsion of fetus in parturition
- milk let-down
- regulation of corpus luteum
A blood system carries hormones down from the hypothalamus through the ____________________________________ to the anterior pituitary.
Hypothalamic-Hypophyseal Portal system
The hypothalamic-hypophyseal portal system originates in the __________________________, where neurons from the hypothalamus release their hormones into the portal system.
Name examples of hormones delivered via the hypothalamic-hypophyseal portal system.
What are the releasing hormones carried by the hypothalamic-hypophyseal portal system?
- 1. Corticotropin releasing hormone (CRH) *Corticotropin aka ACTH
- 2. Thyrotropin releasing hormone (TRH) *thyrotropin aka TSH
- 3. Growth hormone releasing hormone (GHRH)
- 4. Gonadotropin releasing hormone (GnRH)
What are the inhibiting hormones carried by the hypothalamic-hypophyseal portal system?
- 1. Somatostatin-inhibits GH release
- 2. Dopamine-inhibits Prolactin release
GH is very species specific and is mostly an ___________________ hormone but does have some _____________ effects.
What does GH do?
- Frees up energy
- GH goes up when you don't eat to release stored energy
GH levels increase in response to energy deficient states, name those states.
- 1. Starvation: protein deficiency, hypoglycemia, low free fatty acid levels.
- 2. Stresses: exercise, trauma, surgery, fever
- 3. Low energy states: sleep
What are the Indirect Anabolic effects of GH?
- 1. acts on the liver to cause Insulin Growth Factor (IGF-1) secretion: inhibits somatostatin release
- *IGF-1 stimulates protein synthesis, chondrogenesis, and growth (increase muscle mass, decreased muscle breakdown)
What are the Direct Catabolic effects of GH?
- 1. insulin antagonism
- 2. hyperglycemia and lipolysis
- "frees up energy"
Name some GH disorders.
- acromegaly-excess GH
How does Acromegaly effect cats?
usually associated with a GH-secreting pituitary tumor. GH excess almost always has diabetes mellitus.
What are the clinical manifestations of Acromegaly(GH disorder)?
- poorly regulated diabetes
- wide interdental spaces
- large tongue
- enlarged head
Most hormones are under positive control but ______________ is mainly controlled by negative inhibition of ________________.
ADH is synthesized in the supraoptic nucleus of the hypothalamus and released by the posterior pituitary. ADH secretion is stimulated by what?
- increased plasma osmolality sensed by osmoreceptors in the hypothalamus (increased plasma osmolality=increased ADH
- *low blood pressure you want to conserve water to help increase pressure.
ADH increases the permeability of the renal ______________________ to water by activating water channels called ______________________.
- collecting duct
What causes Central diabetes insipidus?
- lack of ADH release by the posterior pituitary
- ex. head trauma or tumor
What causes Nephrogenic diabetes insipidus?
renal collecting duct cells are unresponsive to ADH
Follicular cells of the thyroid gland produces what?
Parafollicular cells (c cells) of the thyroid gland produces what?
large glycoprotein molecule that is the major component of colloid and is the precursor for all thyroid hormones.
What is the enzyme that iodinates the tyrosine molecules and conjugates the MITs and DITs?
What are the effects of TSH?
- Turns on Iodine trapping
- Synthesis of T4 and T3
- endocytosis of colloid
- secretion of T4 and T3