Endocrine 3 - Hypothalamus and Pituitary Flashcards
Paraventricular and supraoptic nuclei are known as _________ neurons that secrete _______ and _______, respectively.
they are known as magnocellular neurons that secrete oxytocin and ADH, respectively.
When the stalk between the hypothalamus and pituitary is disrupted, are all posterior hormones lost forever?
No, the anterior ones are, but the neurons to the posterior pituitary will regrow and re-synapse.
What are the neurophysin peptides and what do they do?
They are large segments of the precursor peptide of oxytocin and ADH that serve to protect oxytocin and ADH from degradation in the bloodstream.
What stimulates ADH release? What does it do?
Low plasma volume or high plasma osmolarity triggers its release. It acts on kidney CD cells to increase H2O permeability –> increased BP and volume.
What stimulates oxytocin release? What does it do?
Parturition, orgasms stimulate its release. It acts on the breast and uterus, stimulates smooth muscle contraction.
Is ADH release more sensitive to plasma osmolarity, or low pressure/volume?
Osmolarity
Are the effects of ADH on urine volume much more sensitive at very low levels of ADH?
Yeah
What receptors and 2nd messengers do oxtyocin and ADH use?
7-transmembrane receptors –> G-alpha protein –> cAMP –> insertion of aquaporins in the cell membranes.
Name the five anterior pituitary cell types and what each one secretes.
- Corticotroph –> ACTH
- Gonadotroph –> LH/FSH
- Thyrotroph –> TSH
- Lactotroph –> PRL
- Somatotroph –> GH
Does GH promote tissue growth directly?
Nope.
GH binds to liver cells –> IGF-1 –> tissue growth
Why are people taller now? Why are New Guinea highlanders short?
People are taller now because we eat more arginine. New Guinea highlanders have a low affinity GH receptor on liver cells.
Is GH-induced lipolysis mediated by IGF-1?
Nope. GH binds directly to adipose cells –> lipolysis
What can excess GH do to glucose metabolism?
It makes people insensitive to insulin.
During what part of the sleep cycle are GH levels the highest? What about cortisol?
GH levels are highest ~1 hour after going to sleep. Cortisol levels are highest after you wake up (~9-10 hours after going to sleep, cuz you need to mobilize glucose from fasting overnight).
Does nipple stimulation increase prolactin production?
In females yeah
What are the three glycoprotein hormones of the anterior pituitary? What do they all have in common? What differentiates them from each other?
TSH, LH, FSH
They all have a common alpha chain, but the beta chain is what confers specificity and interacts with the receptor.
What three things are derived from POMC?
- ACTH
- alpha-MSH
- beta-Endorphin
Where is somatostatin made and what does it do?
Made by delta cells in the GI tract as well as in the hypothalamus. It inhibits secretion of GH and TSH.
Where does CRH come from and what does it do?
Hypothalamus, stimulates release of the POMC-derived hormones (a-MSH, B-Endorphin, ACTH)
Where does TRH come from and what does it do?
Hypothalamus, stimulates release of TSH and prolactin
Where does dopamine come from and what does it do?
Hypothalamus, inhibits release of prolactin.
Define the following feedback loops: ultrashort, short, long.
Ultrashort is when the tissue that releases a hormone is negatively regulated by that exact hormone.
Short is when the immediate target tissue’s product downregulates the initial source (when AP hormones feedback on the hypothalamus).
Long is when the final target organ’s products feedback to the upstream organs.
What is brain derived neurotrophic factor (BDNF)?
Its made in the hypothalamus and is a negative regulator of food intake.
Name a hormone that participates in ultra-short negative feedback.
Somatostatin
Is oxytocin associated with social bonding and blah blah?
Yeah
Growth hormone:
A. is also known as somatomedin
B. is secreted in response to somatostatin
C. has both anabolic and catabolic actions
D. is related in structure to progesterone
E. enhances insulin action
C. has both anabolic and catabolic actions
Preproopiomelanocortin
A. is made by cells in the hypothalamus
B. contains the hormones TSH and LH
C. stimulates the adrenal cortex to make aldosterone
D. is made by cells in the posterior pituitary
E. contains the hormones ACTH and b-endorphin
E. contains the hormones ACTH and b-endorphin
GH inhibition of GHRH release is an example of?: A. short loop negative feedback B. long loop negative feedback C. short loop positive feed back D. long loop positive feedback E. ultrashort loop negative feedback
A. short loop negative feedback
An example of long loop negative feedback is:
A. IGF-1 stimulation of somatostatin release
B. cortisol stimulation of CRH release
C. IGF-1 stimulation of GHRH release
D. prolactin stimulation of dopamine release
E. SST inhibition of TRH secretion
A. IGF-1 stimulation of somatostatin release
