Physio: Hypothalamus and Pituitary Flashcards
Which neurosecretory neuron produced hormones going the posterior pituitary
magnocellular
Which neurosecretory neuron produced hormones going the anterior pituitary
parvocellular
Which hormones are produced by the magnocellular neurons
ADH and Oxytocin
which part of the pituitary gland does it go down to and how?
posterior pit.
ADH and Oxytocin (produced in the neurosecetory cells go down axon to axon endings
Where does ADH go and stimulate
kidney tubules
where does Oxytocin go and stimulate
smooth muscle of uterus
mammary glands
Which hormones are produced by the parvocellular neurons
Release and release-inhibiting hormones
The most important stimulation of ADH release is controlled by …
serum osmolarity
increase in osmolarity, increases ADH release
What other conditions increase ADH release
pain/nausea, hypoglycemia, nicotine/opiates
what substances decrease ADH release
ethanol, ANP
what does ADH do to the kidneys
increases water reabsorption
what does ADH do to the vasculature
increases vasoconstriction via Ca2+
what condition is associated with excess ADH release
SIADH
- tumor production of AVP
- reduced urine, hyponatremia
what condition is associated with decreased ADH release
Diabetes insipidus
- central
- nephrogenic
- excessive thirst (water intake)
Review: central diabetes insip
Neurogenic - decreased hypothalamic release of ADH
underlying cause: trauma, inflammatory, cancer
Responds to desmopressin
Review: nephrogenic DI
decreased renal responsiveness
due to: congential, lithium, or hypokalemia
no response to desmopressin
what are the physical stimulations for the release of oxytocin
suckling of the teat
dilation of the cerix
ORGASM!
what are the physiological role of oxytocin
- contraction of myoepitheial cells of the breast –> ejection of breast milk
- contraction of uterus cells to induce labor –> up-reg of receptors (pos. feedback)
- regression of uterus after delivery
- increases ACTH release by CRH
- vasoconstriction
- stim prolactin release
- elevated during orgasm –> intensifies it
- regulate ejaculation
name the three basophil adenohypophysis and what they secrete?
thyrotropes - TSH
corticotropes - ACTH
gonadotropes - FSH and LH
name the 2 acidophil adenohypophysis and what they secrete?
somatotropes - GH
lactotropes - prolactin
name the 4 stimulatory hypothalamic-releasing hormones (HRH)
CRH, TRH, GHRH, GnRH (LHRH)
name the 2 inhibitory HRH
somatostatin, dopamine
a peptide hormone that binds to a cAMP-dependent GPCR
CRH
what increases ACTH release
- phy and emotion stress
- ADH/AVP.
- sleep-wake cycle–> pulsatile changes peaking in the morning and falling during sleep
what decreases ACTH release
glucocorticoids
stimulates TSH release via a IP-3 dependent pathway
TRH
what increases TSH release
- cold temperature
- sleep-wake cycle–> pulsatile changes peaking in the morning and falling during sleep
what decreases TSH release
- somatostatin
- Thyroid hormone
what other hormonal release does TRH stimulate, what inhibits it
prolactin
dopamine
peptide hormone that causes the secretion of LH and FSH via IP3 dependent pathway
GnRH
polypeptide hormone secreted by lactotropes
prolactin
TRUE or FALSE: during preggers, estrogen increases lactotropes and prolactin gene expression
TRUE
… and … effect the release of GH through what pathway
GHRH…somatostatin
via cAMP-dependent pathway
what inhibits GH release
- high concentration of plasma GH
- high concentration of plasma IGF-1
What factors increase GH release
phy or emotional stress vigorous exercise decrease blood glucose low plasma free fatty acids age starvation/fasting protein deficiency Ghrelin increased arginine Hormones: estrogen, androgens, thyroid
what factors decrease GH release
obesity
increase in blood glucose
what pathway produces IGF-1
tyrosine kinase dependent pathway which is activated via the JAK2 receptor in liver
what does GH do
increases lypolysis, lean body mass (via protein syn), IGF-1 production
decreases movement of glucose into cells
what does IGF-1 do
- increases protein syn in chondrocytes –> increases linear growth of bones
- increases lean body mass
- increases organ size
what is panhypopituitarism
- disease of hypothal or ant.
- congential or destructive
- trauma, ischemia
- isolated GH or gonadotropin deficiency
hypopituitarism in children
Dwarfism: proportional reduction in size (dec GH)
mental retardation: (dec TSH)
lack of sexual devel: (dec FSH, LH)
hypopituitarism in adults
- hypothyroidism
- depressed glucocorticoid production
- loss of sexual fxn
Hyperpituitarism: excess GH
- gigantism
- acromegaly
what is gigantism
found in ADOLESCENCE
- over activity in acidophils d/t adenoma
- s/s: hyperglycemia and diabetes
- may develop panhypopituitarism if tumor destrys gland
what is acromegaly
found in ADULT
- acidophilic tumor after puberty
- no incr in height BUT bones thicker (hands/feet) and soft tissue growth (nose, forehead, jaw, cartilage)
- s/s: cardiac hypertrophy, visual impairemnt
Hyperpituitarism: excess GH
- gigantism
- acromegaly
what is gigantism
found in ADOLESCENCE
- over activity in acidophils d/t adenoma
- s/s: hyperglycemia and diabetes
- may develop panhypopituitarism if tumor destrys gland
what is acromegaly
found in ADULT
- acidophilic tumor after puberty
- no incr in height BUT bones thicker (hands/feet) and soft tissue growth (nose, forehead, jaw, cartilage)
- s/s: cardiac hypertrophy, visual impairemnt
most common pituitary tumor
prolactinomas due to excess prolactin
what can cause hyperprolactinemia
dopamine antagonist drug treatment
pituitary dwarfism- hyposecretion
- growth is severely impaired
- metabolically normal
- tendency for hypoglycemia and insulinopenia
what disorder is associated with GH insensitivity
Levi-Laron dwarfism
- GH receptor defective
- failure to generate IGF’s