3. Hypothalmic-Pituitary Relationships Flashcards
(33 cards)
What 2 things are secreted by the majority of the cell bodies in the supraoptic nuclei?
Antidiuretic hormone (ADH).
Neurophysin II.
What is the elementary precursor for oxytocin?
What is the elementary precursor for ADH?
Preprooxyphysin.
Prepropressophysin.
Recall the pathway for GH regulation and check it against the pathway on the reverse.
What is more important for the regulation of ADH, blood volume or osmolarity?
Osmolarity. Only a 1% change is required to cause an effect, whereas a 10% change in blood volume is necessary.
What is released by a lactotroph?
What hypothalamic hormone triggers its release?
Prolactin.
TRH.
How does growth hormone promote growth?
What specific cell type is responsible for growth hormone’s effect on bones?
Increases protein synthesis (organ growth).
Increases uptake of amino acids.
Stimulates synthesis of DNA, RNA, and new proteins.
Increases metabolism in and proliferation of chondrocytes.
Chondrocytes are responsible for growth hormone’s effect on bones.
What cell population does corticotropin-releasing hormone act upon?
What hormone is ultimately released as a result?
Corticotrophs.
ACTH
How might damage to the pituitary gland cause diabetes insipidus?
Damage to the cells which release antidiuretic hormone.
How can we differentiate between central vs. nephrogenic diabetes insipidus?
In central diabetes insipidus ADH will be low, and patient will respond to desmopressin.
In nephrogenic diabetes insipidus, ADH will be high and patient will not respond to desmopressin.
What are the diabetogenic effects of growth hormone?
Causes insulin resistance.
Decreases tissue glucose uptake and utilization.
Increases lipolysis and adipose tissue.
Results in increased blood insulin levels (which causes the insulin resistance).
What are the three families of anterior pituitary hormones?
The ACTH family.
The FSH, LH, and TSH (FLaT) family.
Prolactin and GH family.
What molecule mediates growth hormone’s growth effects?
Somatomedins.
What cells of the hypothalamus produce the most oxytocin?
Cells of the paraventricular nucleus.
What is affected in a primary / secondary / tertiary endocrine disorder respectively?
Primary disorder: peripheral endocrine gland defect.
Secondary disorder: pituitary gland defect.
Tertiary disorder: hypothalamus defect
Why do we look at IGF-I levels when suspecting a diagnosis of acromegaly?
Because growth hormone leads to the secretion of IGF-I, which should then inhibit growth hormone secretion. If both growth hormone secretion and IGF-I secretion are high, something else is stimulating growth hormone secretion.
Also, growth hormone levels can fluctuate throughout the day, whereas IGF-I levels remain constant.
Which of the anterior pituitary hormones have an α/β subunit?
The FLaT family:
follicle stimulating hormone, luteinizing hormone, and thyroid stimulating hormone.
What would we expect to see (increase or decrease) in the levels of growth hormone, somatomedin, and insulin during periods of fasting?
Growth hormone increases.
Somatomedin decreases (to decrease the growth effects of growth hormone).
Insulin decreases.
What is the difference between central and nephrogenic diabetes insipidus?
In central diabetes insipidus, either the hypothalamus or the posterior pituitary is damaged, and ADH is not being produced.
In nephrogenic diabetes insipidus kidneys are unable to respond to the elevated levels of plasma ADH. Drugs like lithium and kidney disease/damage will result in nephrogenic DI.
What pathologies can cause a growth hormone deficiency?
Decreased secretion of growth hormone releasing hormone (hypothalmic dysfunction).
Decreased growth hormone secretion.
Failure to generate somatomedins.
Growth hormone or somatomedin resistance (deficiency of receptors).
How might damage to the anterior pituitary cause loss of pigmentation?
Damage to ACTH secreting cells (corticotropic cells) can cause lack of pigmentation due to a loss of melanocyte stimulating hormone (MSH)
What cell type is the most significant in the anterior lobe of the pituitary?
The somatotroph population.
What does somatostatin do to the pituitary gland?
Inhibits somatotrophs from producing growth hormone.
What is the effect of damage to growth hormone secreting cells of the anterior pituitary in adults?
No effect.
How does hyperprolactinemia affect FSH and LH?
Hyperprolactinemia causes prolactin to negatively feedback, through a long feedback loop, to the hypothalamus – decreasing the amount of gonadotropin releasing hormone reaching the anterior pituitary, and therefore reducing the amount of prolactin secreted – as well as the amount of follicle stimulating hormone and luteinizing hormone.
