Hypothalamic Pituitary Relationships And Biofeedback Pt. 1 Flashcards
What will a tumor of the pituitary gland cause?
Will put pressure on optic nerves
Can present w/ visual problems, dizziness
How is the posterior pituitary gland connected to the Hypothalamus?
Via hypophyseal stalk
And via neural signal hypothalamic-hypophyseal tract
What makes up the
Hypothalamic-hypophyseal tract?
Axons from SON and VPN carrying ADH and Oxytocin
What is the anterior pituitary gland?
Collection of endocrine cells derived from primitive foregut
What does the anterior pituitary secrete?
GH FSH LH ACTH TSH MSH Prolactin
How is the ANterior pituitary connected to the hypothalamus?
Via hypothalamic-hypophyseal portal blood vessels
What is in the ACTH family?
When is it released?
corticotrophs (ACTH)
When when CRF comes from hypothalamus
What is CRF?
Corticotropin releasing factor
What is in the TSH, FSH, LH family?
Thyrotrophs -TSH
Gonadotrophs- FSH and LH
What is TSH released from Thyrotroph cells?
When TRH come from hypothalamus
Thyrotrophin releasing hormone
When are FSH and LH released from Gonadotroph cells?
When GnRH comes from hypothalamus
Gonadotrophin releasing hormone
What is in the GH, Prolactin family?
Somatotropin - GH
Lactotrophs - Prolactin
What releases GH from Somatotropic cells?
When GHRH comes from hypothalamus
Growth hormone releasing hormone
What will inhibit the release of GH from somatotropic cells?
Inhibited when Somatostatin comes from hypothalAmus
Somatostatin = growth hormone inhibiting hormone
What is Prolactin released from lactotrophic cells?
When TRH is elevated
(Thyrotrophin releasing hormone)
Otherwise it is ALWAYS INHIBITED
What inhibits the release of Prolactin from Lactotrophic cells?
When Prolactin-inhibiting factor (PIF) comes from the hypothalamus
What is a primary endocrine disorder?
◦ Low or high levels of hormone due to defect @ PERIPHERAL ENDOCRINE GLAND
What is a secondary endocrine disorder?
◦ Low or high levels of hormone due to Defect @ PITUITARY GLAND
What is a tertiary endocrine disorder?
◦ Low or high levels of hormone due to Defect @ hypothalamus
What are the different HP axes?
HP-gonad
HP-liver
HP-prolactin
HP-thyroid
HP-adrenal
In the HP-Gonad axis what is the hypothalamic hormone?
GnHR
Gonadotrophin releasing hormone
In the HP-Gonad axis, what are the pituitary hormones released?
LH (lutenizing hormone)
FSH (Follicle stimulating hormone)
What can inhibit the release of GnHR?
◦ Extreme energy deficits
(anorexia nervosa or starvation)
◦ Extreme exercise
◦ Depression
What characterizes the release of GnRH?
Pulsatile release
What is the function of FSH and LH?
‣ Promotes Estrogen and progesterone secretion in Females
‣ promotes Testosterone production in Males
A normal men’s rural cycle is dependent upon what?
LH
FSH
What is the target of LH?
In males?
Females?
Males:
LH—> Leydig cell —> testosterone
Females:
LH —> Theca cell —> Androgens
What is the target of FSH?
In males?
Females?
Males:
FSH —> Sertoli cells —> Androgen binding protein & inhibin
Females:
FSH —> Granulosa cells —> Progestins, estrogens, inhibin
What will androgen binding protein do?
Bind testosterone and do spermatogenesis
How is the HP-gonad axis regulated in males?
‣ Testosterone from Leydig cell will feedback = Inhibit Pituitary LH and Hypothalamus GnRH
‣ Inhibin from Sertoli cell will feed back and inhibit pituitary FSH
How is the HP-gonad axis regulated in women?
- Progesterins & Estogens inhibit pituitary LH and FSH and Hypothalmaus GnRH
- Inhibin from Granulosa Cell inhibits pituitary FSH
What produces GH?
Somatotropes
What are the direct targets of GH?
Liver and bone
What is the pathway for Growth Homrone?
GH —> GH R. —> jak stat signaling
What inhibits GH?
Somatostin (GHIH)
IGF-1
What will stimulate the release of GH?
‣ Fasting/hunger/starvation ‣ Hypoglycemia ‣ Hormones of puberty ‣ Exercise ‣ Sleep ‣ Stress
What are the 3 functions of GH?
Growth (Hypertrophy of cells)
Cell reproduction (Hyperplasia)
Metabolism
What are the hypothalamic hormones secreted in the Growth Hormone pathway?
Growth hormone releasing hormone (GHRH)
GHIH (will inhibit release of GH from anteiror pit.)
What will act as negative feedback to the Growth Hormone Releasing HORmone in the Hypothalamus?
Growth hormone
In the Growth hormone pathway, what does the Liver secrete?
Insulin-like growth factor (IGF-1)
What is the function of IGF-1?
What is another name for it?
Stimulates hypertorphy and hyperplasia
Somatomedins C
What are the feedback mechanisms of IGF-1?
+ to GHIH
- to GH
If the release of GHRH is defective, what is the tx?
What kind endocrine disorder is this?
Soma relain
Tertiary endocrine disorder (defect @ hypothalamus)
If GH is too low, what is the treatment?
What kind endocrine disorder is this?
Somatotropin
Somatrem
Secondary endocrine disorder (pituitary defective)
If the liver fails to release IGF-1 when stimulated by GH, what is the treatment?
Mecasermin
What could cause the liver to not release IGF-1?
What kind endocrine disorder is this?
GH deficiency
GH abs
Primary endocrine disorder
If you are in a Fed state, what happens to IGF-1 and GH?
What are the results?
Increased carbs and proteins —> GH
GH —> liver —> IGF-1
Mitogenesis, lypolysis, differentiation
What will a fed state, cause in bone?
‣ Osteoblasts production
‣ Collagen production
‣ Bone matrix production
What will happen to IGF-1 and GH, if you are in FED state but with NO Protein?
Results?
Increased carbs —> insulin available
But no AAs available
GH = INHIBITED
Liver —X—> IGF-1
Lipogenesis, carb storage (weight gain)
What happens to IGF-1 and GH, if you are in FASTING STATE?
Causes?
Results?
Decrease carbs —> inadequate insulin
Increased use of Proteins —> AAs available
Causes peripheral metabolism to use LIPIDS as ENERGY source now
Lyolysis, ketogenic metabolism, diabetogenic (insulin insensitivity)
How does GH promote lipolysis but also promote insulin insensitivity?
Raises blood glucose by DECREASING peripheral glucose uptake
Stimulates hepatic gluconeogenesis
How does GH have a Diabetogenic effect?
Decreased glucose uptake and utilization by target tissues
Increases lipolysis in adipose tissue
Increases blood insulin levels = raises blood glucose levels
—> insulin resistance
How does GH increase protein synthesis and organ grwoth?
Increase uptake of AAs
Stimulates synthesis of DNA, RNA, and proteins
(Mediated by IGF-1)
How does GH increase linear growth?
Increases metabolism in cartilage forming cells and chondrocyte proliferation
Thru stimulating DNA, RNA, and Protein synthesis (mediated by IGF-1)
When is GH primarily released?
What can mess w/ GH secretioN?
During sleep
Sleep disturbances
When will GH peak during the day?
W/ exercise
When will GH have its peak in life?
During puberty
What can cause a GH deficiency?
- decreased secretion of GHRH due to hypothalamic dysfunction
- Decreased GH secretion
- Failure to generate somatomedins
- GH or somatomedin resistance (deficiency of receptors)
What can cause a GH excess?
• Grwoth hormone secreting pituitary adenoma
What are the consequences of GH excess
BEFORE puberty?
AFTER puberty?
Before = gigantism
After = acromegaly
What is acromegaly?
◦ Rare disease
◦ Characterized by xs growth of soft tissue, cartilage, & bone in face, hands and feet
◦ Develop gradually
What is acromegaly caused by?
◦ Caused by prolonged and excessive secretion of Growth Hormone (GH) in adult life AFTER closure of bone epiphyses
What is the test for Acromegaly?
What will be elevated?
‣ Evaluated serum GH and IGF-1 levels
‣ Failure to suppress GH production in response to an oral load of glucose
‣ Pituitary enlargement on MRI
When is secretion of prolactin increased?
5th week of pregnancy
What is the unique characteristic about Prolactin secretion?
◦ PRL is under tonic inhibition by hypothalamic dopamine
What is the function of Prolactin?
Stimulate and maintain lactation
Suppresses GnRH
• Thus inhibiting LH and FSH
◦ Decreases reproductive function
◦ Suppresses sexual drive
What are the stimulatory factors for PRL secretion?
‣ Pregnancy (estrogen) ‣ Breast-feeding (Suckling) ‣ Sleep ‣ Stress ‣ TRH
What are the inhibitory factors for PRL secretion?
‣ Dopamine
‣ Dopamine agonists
‣ Somatostatin (GHIH)
‣ Prolactin via negative feedback
What is prolactinoma caused by?
Sxs?
pituitary adenomas (mostly causes Prolactinoma (60%))
Sxs related to hormones action on body (suppression of GnRH - no periods?)
What hyperpituitarism cause?
GH, PRL, LH & FSH, ACTH, TSH
- Xs of GH = acromegaly/gigantism
- Xs of PRL = prolactinoma
- XS of LH and FSH = non functioning adenoma
- XS of ACTH (cortisol) = Cushing’s Disease
- XS of TSH = Secreting adenoma
What can hypopituitarism cause?
GH, FSH/LH, TSH, ACTH, ADH
‣ GH = kids short, adults no effect
‣ FSH/LH = infertility, hypogonadism in males and females (reduced sperm count, menstrual irregularity)
‣ TSH = hypothyroidism
‣ACTH = loss of pigementation, hypoadrenalism
‣ ADH = Diabetes insipidis
What can cause hypopituitarism?
Brain damage
Pituitary tumors
Non pituitary tumors (Craniopharyngioma)
Infections
Sheehan syndrome
Aids
Pitutiary hyplasia/aphasia
Genetic disordes
What is Sheehan syndrome?
Results in?
In pregnancy
Pitutiary enlarged, vulnerable to infarction
Results: HYPO-pituitarism
What makes oxytocin?
Paraventricular Nucleus of the HYpothalamus
Dennis was wroooooong
Where are the cell bodies of ADH neurons?
In the SON nuclei of the hypothalamus
Where are the cell bodies of Oxytocin neurons?
In Paraventricular nucleus of hypothalamus
How is oxytocin secreted?
Where is it secreted to?
In hypothalmaus, pro-oxyphysin is cleaved and packed into vesicles
Travels via hypothalamic-hypophyseal tract to posterior pituitary
To breast and uterus
What are the 2 functions of oxytocin?
- Milk ejection
2. Uterine contraction
What produces breast milk? What ejects breast milk?
- Prolactin
2. Oxytocin
What is Milk letdown?
Stimulated by?
Oxytocin stimulates contraction of myoepithelial cells lining milk ducts to eject milk
What is the stimulus for milk ejection?
Suckling
Sight/sound/smell of infant
What is the stimulus for uterine contraction by oxytocin?
Dilation of cervix or organism
What is pitocin?
Synthesized Oxytocin that can be administered to induce labor
