2-2-16-Hypothalamic-Pituitary Relationships (Lopez) Flashcards
The relationship between the hypothalamus and the anterior pituitary is ___
The relationship between the hypothalamus and the posterior pituitary is ___
Both neural and hormonal
Neural
The anterior pituitary is connected to the hypothalamus by ___
Hypothalamic-hypophysial portal vessels
The ___ provide most of the blood supply to the anterior pituitary
hypothalamic-hypophysial portal vessels
___ is when you have low or high levels of hormone due to a defect in the peripheral endocrine gland (i.e., thyroid gland)
Primary endocrine disorder
___ is when you have low or high levels of hormone due to a defect in the pituitary gland
Secondary endocrine disorder
____ is when you have low or high levels of hormone due to a defect in the hypothalamus
Tertiary endocrine disorder
In the anterior pituitary,
\_\_\_ releases ACTH \_\_\_ releases TSH \_\_\_ releases FSH and LH \_\_\_ release GH \_\_\_ releases prolactin
Corticotroph=ACTH Thyrotroph=TSH Gonadotroph=FSH and LH Somatotroph=GH Lactotroph=Prolactin
List the hypothalamic releasing hormone for the secretion of:
a-TSH B-ACTH C-LH, FSH D-GH E-Prolactin
A-TRH B-CRH C-GnRH D-GHRH E-PIF (dopamine) or TRH (elevated)
The anterior lobe hormones can be separated into these organizational families based on structural and functional homology
- ACTH family
- TSH, FSH, and LH family
- GH and prolactin family
___ has melanocyte-stimulating hormone activity
ACTH
In ___ disease, ACTH levels increase and skin pigmentation is a symptom of this disorder
Addison
ACTH stimulates these 2 zones of the adrenal gland:
Medulla and Cortex
The actions from GH result from 2 different effects:
___ has an effect on the target tissues (e.g., skeletal m., liver, adipose)
__ is mediated by the production of somatomedins in the liver (e.g., IGF-1)
Direct
Indirect
This particular action/effect from GH causes an increase in [blood glucose] which can cause insulin resistance, decreased glucose uptake and utilization by target tissue, increased lipolysis in adipose. The result is an increase in blood insulin levels.
Diabetogenic effect
This particular action of GH leads to an increased uptake of AA’s, stimulation of synthesis of DNA, RNA, and protein, and is mediated by somatomedins.
Increased protein synthesis and organ growth
This particular action of GH stimulates synthesis of DNA, RNA, protein, is mediated by somatomedins, and increases metabolism in cartilage-forming cells and chondrocyte prolfieration
Increased linear growth
Acromegaly can be a result of what?
GH excess
GH excess is mostly due to a GH-secreting pituitary adenoma
What happens if you have GH excess before puberty?
What happens if you have GH excess after puberty?
Gigantism
Increased periosteal bone growth, increased organ size, increased extremities size, coarsening of facial features, insulin resistance, and glucose intolerance
___ supports the actions of estrogen and progesterone
Prolactin
List 3 actions of prolactin:
Breast development: at puberty –> stimulate proliferation and branching of mammary ducts; during pregnancy –> stimulate growth and development of the mammary alveoli
Lactogenesis–> induce synthesis of lactose, casein, and lipids
Suppression of ovulation –> inhibits synthesis and secretion of GnRH
___ is a condition of inadequate or absent production of the anterior pituitary hormones.
Panhypopituitarism
What are some causes of hypopituitarism?
Brain damage–> traumatic brain injury, subarachnoid hemorrhage, irradiation, stroke
Pituitary tumors–> adenomas
Non-pituitary tumors–> cranipharyngioma: most common tumor affecting the HP axis in children
Infections–> meningitis, encephalitis, hypophysitis
Infarction–> sheehan syndrome: pituitary in pregancy is enlarged and more vulnerable to infarction
Autoimmune disorders, pituitary hypoplasia or aplasia, genetic or idiopathic causes
___ syndrome is when the pituitary gland is enlarged and more vulnerable to infarction during pregnancy
Sheehan
Most pituitary tumors are ___ and occur spontaneously
pituitary adenomas
___ adenomas release an active hormone in excessive amounts into the bloodstream. The pt usually experience symptoms related to the hormone action in the body
Hormone-producing pituitary
A prolactinoma is a tumor that overproduces prolactin and is associated with ____
Hypogonadism and galactorrhea
Acromegaly and gigantism are caused by an excess of ___
GH
___ is caused by a pituitary tumor stimulating an overproduction of cortisol
Cushings disease
The precursor peptide of ADH is ___
The precursor peptide of Oxytocin is ___
Preprossophysin
Prepro-oxyphysin
___ is the major hormone concerned with the regulation of body fluid
ADH
Prepropressophysin to Propressophysin in the hypothalamus –> Goes down hypothalamic-hypophyseal tract (axons of neurons) to the posterior pituitary –> ADH in the posterior pituitary –> when needed, ADH into the bloodstream –> target tissues of kidneys and blood vessel
What are triggers of ADH secretion?
- Decreased BP –> cardiac and aortic baroreceptors –> sensory neuron to hypothalamus
- Decreased arterial stretch due to low blood volume –> atrial stretch receptors –> sensory neuron to hypothalamus
- Increased osmolarity –> hypothalamic osmoreceptors –> interneuron to hypothalamus
These all act on hypothalamic neurons that synthesize ADH –> ADH released from posterior pituitary
Secretion of ADH is most sensitive to ___ changes. An increased of only 1% of this factor will increased ADH secretion
Osmolarity
Aquaporin-2 channels can be found on the ___ membrane and Aquaporin-3 channels can be found on the ___ membrane
Aq2=Apical
Aq3=Basolateral
Too little water will result in ___ levels of ADH in the bloodstream
Too much water will result in ___ levels of ADH in the bloodstream
Increased
Decreased
When the hypothalamus detects too little water, the pituitary gland releases ADH, the kidneys remove less water from the blood and the urine becomes ___
More concentrated
Will also increase thirst levels as plasma [ADH] exceed ~295 mOsm
WHen the hypothalamus detects too much water in the blood, the pituitary gland releases less ADH, the kidneys remove more water from blood and the urine becomes ____
More dilute
___ is characterized by a lack of an effect of ADH on the renal CD which causes frequent urination and a large volume of dilute urine
Diabetes Insipidus
___ results from damage to the pituitary and destruction of the hypothalamus that leads to a lack of or decrease in plasma ADH
Central DI
___ is caused by drugs such as lithium or chronic disorders such as polycystic kidney disease and sickle cell anemia. The kidneys are unable to respond to ADH (Increased plasma ADH)
Nephrogenic DI
Desmopressin can be used to treat ___ DI
Central DI–> Desmopressin does not work for Nephrogenic DI
Desmopressin prevents water excretion
Plasma ADH levels are expected to be lower than normal in ___
Plasma ADH levels are expected to be higher than normal in ___
Central DI
Nephrogenic DI
___ is characterized by excessed ADH secretion, excessive water retention, and/or hypoosmolarity fails to inhibit ADH release
SIADH
How do you treat SIADH?
Fluid restriction
IV hypertonic saline
V2 receptor antagonist
Demeclocycline
Predict anatomic/physiologic changes as a result of pituitary failure and the following hormones: A-GH B-FSH/LH C-TSH D-ACTH E-ADH
A-Children: short stature, Adults: no effect
B-Infertility, hypogonadism, reduced sperm count in men; Menstrual irregularity in women
C-Hypothyroidism
D-Loss of pigmentation, hypoadrenalism
E-Diabetes insipidus
___ is a collection of axons whose cell bodies are located in the hypothalamus
Posterior pituitary –> secretes neuropeptides
- Supraoptic nucleus (primarily ADH)
- Paraventricular nucleus (primarily oxytocin)
SIADH is characterized by ___
Euvolaemia –> Total body water is increased but normal total body sodium
