Endocrine Physiology Flashcards
G-protein-coupled receptors:
GTP is stimulated by: _________ and inhibited by _________ and __________
Stimulated by Guanine nucleotide exchange factors (GEFs)
Inhibited by GTPase-accelerating proteins (GAPs) and RGS proteins (regulation of G protein signaling)
Signal transduction systems used by all hypothalamic hormones except CRH:
IP3/DAG
Signal transduction system used by:
ADH (V2 receptor: collecting duct of kidneys)
cAMP
Signal transduction system used by:
ADH (V1 receptor: blood vessels)
IP3/DAG
Signal transduction system used by:
Leptin, IGF-1, Insulin, EPO, GH, Prolactin
Tyrosine kinase
Signal transduction system used by:
ANP, EDRF, nitric oxide
cGMP
Signal transduction system used by: Angiotensin II (epithelial cells)
cAMP
Signal transduction system used by: Angiotensin II (vascular smooth muscle)
IP3/DAG
Signal transduction system used by:
Catecholamines (B1 and B2 receptors)
cAMP
Signal transduction system used by:
Catecholamines (A1 receptors)
IP3/DAG
Signal transduction system used by:
CRH
cAMP
Signal transduction system used by:
Glucagon, Somatostatin, PTH, HCG, Calcitonin, ACTH, LH, FSH, TSH, secretin
cAMP
Signal transduction system used by:
GnRH, TRH, GHRH, oxytocin
IP3/DAG
Transport of steroid hormone
Bound to proteins
Active form of steroid hormones
Free, unbound form
Main site of inactivation of hormones
Liver
Mechanism for removal of hormones
Liver, kidneys
Number of hormone receptors - constant or variable?
Variable
Minimum amount of hormone to produce effect
1 picogram per mL
Onset of hormone effects
seconds to months
What type of hormone interaction?
Epinephrine and NE on the heart
Synergistic, additive (simultaneous, same effect)
What type of hormone interaction?
FSH and testosterone effects on spermatogenesis
Synergistic, complementary (different time, same effect)
What type of hormone interaction?
Cortisol on Epinephrine and NE on blood vessels
Permissive
What type of hormone interaction?
T3 on epinephrine on lipolysis
Permissive
What type of hormone interaction?
Estrogen on prolactin effects on the breasts during pregnancy
Antagonistic
Hormone has biologic actions that directly or indirectly inhibit further secretion of the hormone
Negative feedback
Hormone has biologic actions that directly or indirectly stimulate further secretion of the hormone
Positive feedback
Give an example of negative feedback that does not utilize the HPA:
Insulin
Give 3 examples of positive feedback involving hormones:
- Estrogen induced LH and FSH surge
- Oxytocin during labor
- Oxytocin during lactation
Decrease in receptor number or receptor affinity by decreased synthesis, increased degradation or inactivation
Down-regulation
Increase in receptor number or receptor affinity by increased synthesis, decreased degradation or inactivation
Up-regulation
The pituitary gland lies in the sella turcica, and connected to the ______ of the hypothalamus via pituitary/hypophysial stalk
median eminence
Transmit hypothalamic hormones to the pituitary without passing through the systemic circulation
Hypothalamic-hypophysial portal blood vessels
The anterior pituitary is derived from the:
oral ectoderm (Rathke’s pouch)
FSH, LH, ACTH, TSH and MSH are what kind of cells?
basophilic cells
GH and prolactin are what kind of cells?
acidophilic cells
The posterior pituitary is derived from the:
neural ectoderm (neural outgrowth of the hypothalamus)
Hormones from the posterior pituitary (pituicytes):
Vasopressin, oxytocin
If the pituitary stalk is damaged, all anterior pituitary hormones would decrease, except:
Prolactin
In terms of number, what are the top 2 cells in the anterior pituitary?
Somatotropes (40%), Corticotropes (20%)
What are the “3 families” of hormones in the anterior pituitary?
TSH, LH, FSH (same alpha unit, unique beta unit)
MSH, ACTH (derived from POMC)
GH, Prolactin
Growth hormone is release in pulsatile fashion every __ hours
2 hours
Nocturnal peak of growth hormone is:
1 hour after stage 3 or 4 sleep
Differentiate somatotropin from somatostatin from somatomedin
Somatotropin: growth hormone
Somatostatin: stops growth hormone
Somatomedin: IGF-1
What are the direct actions of Growth hormone?
- Increases blood glucose levels
- Increased protein deposition in muscles and other tissue
- Increased lipolysis
- Increased IGF-1 production
- Possible anti-aging effects
What is the indirect action of growth hormone (via IGF-1)?
Increases bone length and bone thickness
Secretion of growth hormone requires normal plasma levels of what hormone?
Thyroid hormone
Achondroplasia is the most common cause of dwarfism. It is caused by a defect in:
FGF receptor 3
Stimulates milk production by synthesis of lactose, casein, lipids; inhibits ovulation or spermatogenesis by decreasing GnRH; stimulates breast development during puberty and pregnancy
Prolactin
What is one possible side effect of anti-psychotic drugs that involve prolactin?
Amenorrhea-Galactorrhea
What stimulates prolactin?
Pregnancy (estrogen), breast feeding
What inhibits prolactin?
Dopamine, bromocriptine