Growth Hormone And Posterior Pituitary Flashcards
Where is GH released from
Anterior pituitary
What triggers GH to be released from anterior pituitary
GHRH
What is GH release inhibited by
Somatostatin from the hypothalamus
What are the effects of GH
- regulates blood levels of all energy sources
- causes protein synthesis and organ growth
- causes linear bone growth
- produces somatomedins (IGF, insulin like growth factors) whihc function like GH in some target tissues
How is GH released
In a pulsatile fashion throughout life, but slows as you age
What are the two best stimulators for growth hormone q
Exercise and sleep
What are the two best inhibitors for GH
Obesity and old age
What are all the stimulators of GH
- decreased glucose concentration
- decreased free FA cxn
- arginine
- fasting and starvation
- hormones of puberty (estrogen, testosterone)
- exercise
- stress
- stage III and IV sleep
- a-adrenergic agonists
What are inhibitors of GH
- increased glucose cxn
- increased FA cxn
- obesity
- senecence
- somatostatin
- GH
- B-adrenergic agonists
- pregnancy
GH mechanism of action
- binds its receptor and causes phosphorylation of intracellular proteins (STATs)
- these intracellular proteins alter transcription and translation
- alter protein production and expression
What is GH similar to in its mechanism of action
Steroid hormone. It is a peptide
What does GH increase
Blood glucose, amino acid and lipid levels
What is the importance of GH increasing blood glucose, amino acid and lipid levels
- provides energy sources for growth
- has an anti-insulin like effect
Somatomedins (IGF-1) and GH
Increases utilization of these energy sources for growth, acts like insulin
How do GH and somatomedins (IGF-1) work together
To allow for growth of organs, muscle tissue and long bones
Which of the following could be a pathology associated with hypersecertion of growth hormone
Type 2 diabetes
What is growth hormone deficiency usually due to
Pituitary damage
Congenital GH deficiency
- failure to grow and develop normally in first months
- must give GH to allow catch-up growth
GH deficiency in children
- acquired
- short stature, possibly dwarfism if not corrected
- underdeveloped features
- poor bone density
- Low muscle mass
- late to puberty
Deficiency of GH in adults
- acquired
- loss of lean muscle, obesity
- poor bone density
- increased risk of cardiovascular disease
Growth hormone excess
Newborns and children
- pituitary gigantism
- very rare
- increased linear growth
- very tall
- usually early mortality due to overgrowth of organs
Acromegaly
- GH excess after closure of growth plates
- usually a pituitary tumor
- growth of all soft tissues and organs
- cardiovascular issues
- characteristic physical features
- growth of fingers, nose, ears (cartilage)
- no gain in height
- insulin resistance
- if pituitary tumor is large, can cause peripheral vision loss
Why can a pituitary tumor cause a bitemporal vision loss
Compression of the optic chiasm
What is the posterior pituitary
- not glandular tissue
- neurohypophysis
- axons and nerve terminals on neurons in hypothalamus
What hormones does the posteiror pituitary make
It doesn’t make any directly, it only stores some that are made in the hypothalamus
What are the hormones that are stored in the posterior pituitary
Oxytocin and ADH (vasopressin)
What nucleus of the hypothalamus is ADH made in
Supraoptic nucleus
What hypothalamic nucleus is oxytocin made in
Paraventricular nucleus
When is ADH released
When plasma Osm is too high and when effective blood volume is too low
What does release of ADH do
Causes insertion of aquaporins into kidney tubule, allows reabsorption of water-V2 receptor
Besides water retention, what does ADH do
It’s a vasoconstrictor
- V1 receptors
- also called vasopressin for this reason
What are the stimulators factors of ADH
- increases serum Osm
- decreases ECF volume
- AngII
- pain
- nausea
- hypoglycemia
- nicotine
- opiates
- antineoplastic
- drugs
What are some inhibitory factors of ADH
- decreased serum Osm
- ethanol
- a-adrenergic agonists
- ANP
SIADH
- too much ADH
- retain water, cant make dilute urine
Diabetes insipidus
- not enough ADH
- due to lack of ADH-central
- due to lack of V2 receptors-nephrite ic
What is central diabetes insipidus
Not enough ADH due to lack of ADH
What is nephrogenic diabetes insipidus
Not enough ADH due to lack of V2 receptors
What is oxytocin involved with
Reproductive functions
- milk ejection during breast feeding
- contractions of the uterus during birth
What is oxytocin controlled by
Both physical and mental cues
What are some thins that oxytocin can be used for
Induce labor and stop post partum hemorrhage
Stimulators factors for oxytocin
- suckling
- sight, sound, or smell of the infant
- dilation of the cervix
- orgasm
Inhibitory factors for oxytocin
Opioids
