SM_172b: Hypothalamus-Pituitary Basic Flashcards
Unlike the nervous system, endocrine system is ____
Unlike the nervous system, endocrine system is anatomically discontinuous
Compare the nervous and endocrine systems
Nervous and endocrine systems
- Nervous: electrical and chemical communication, endocrine: only chemical
- Nervous: reacts and stops quickly, endocrine: reacts slowly and effect is long lasting
- Nervous: response declines, endocrine: response persists
- Nervous: targeted and specific, endocrine: general and widespread
Describe the anterior and posterior pituitary
Anterior and posterior pituitary
Describe hypothalamo-anterior pituitary-target organ relationships
Hypothalamo-anterior pituitary-target organ relationships
Hypothalamic hormones control the hormones released from the ____
Hypothalamic hormones control the hormones released from the pituitary
Hypothalamus stimulates pituitary with ____ hormones or blocks the pituitary with ____ hormones
Hypothalamus stimulates pituitary with releasing hormones or blocks the pituitary with inhibitory hormones
_____ and _____ act on hypothalamic pulse generators to affect pituitary hormone release
Sleep-wake homeostasis and circadian rhythms act on hypothalamic pulse generators to affect pituitary hormone release
- Circadian rhythms: suprachiasmatic nucleus
Hormone secretion is pulsatile based on ____
Hormone secretion is pulsatile based on circadian rhythms
_____ in gonadotropin secretion occurs with change from pulsatile to continuous GnRH administration
Decrease in gonadotropin secretion occurs with change from pulsatile to continuous GnRH administration
Describe prolactin secretion
Prolactin secretion
- Hypothalamus stimulates pituitary via TRH and VIP
- Pituitary secretes prolactin
- Acts on breast and other tissues
- Positive feedback on hypothalamus
Describe growth hormone regulation
Growth hormone regulation
- Hypothalamus secretes GHRH
- Pituitary secretes GH
- Acts on liver and bones
- IGF-1 secreted which inhibits hypothalamus and pituitary
Binding to the extracellular domain of the growth hormone receptor causes ___
Binding to the extracellular domain of the growth hormone receptor causes dimerization of receptor subunits for cross phosphorylation
Insulin-like growth factors have high identity in the ___ and ___ chains
Insulin-like growth factors have high identity in the A and B chains
_____ bind circulating IGF with high affinity and specificity
Insulin-like growth factor binding proteins bind circulating IGF with high affinity and specificity
- Act as carriers of IGF in plasma
- Prolong the half-life of IGF in circulation
- Regulate IGF access to receptor in extracellular fluid
Plasma IGF-I and GH concentrations increase during ____
Plasma IGF-I and GH concentrations increase during prepubertal period
Inactivation of ____ or ____ in men leads to greater height
Inactivation of estrogen receptor or aromatase in men leads to greater height
Describe hormones involved in growth
Hormones involved in growth
- Thyroid hormone: growth severely stunted in hypothyroid children
- Insulin: deficiency often blocks growth, hyperinsulinism spurs excessive growth
- Androgens: play role in pubertal growth spurt, stimulate protein synthesis in many organs, effect depend on presence of growth hormone, depend on aromatization to estrogens
- Estrogens
Hypothyroid children have ____ growth
Hypothyroid children have stunted growth
Growth hormone acts in ____, ____, ____, and ____
Growth hormone acts in linear growth, bone, muscle, and adipose tissue
- Linear growth: promotes epiphyseal growth (IGF-1)
- Bone: increases osteoclast differentiation / activity, increases osteoblast activity, increases bone mass by endochondral bone formation
- Muscle: increases amino acid transport, increases nitrogen retention, increases lean tissue and increases energy expenditure
- Adipose: acute insulin-like effects
Dual effector theory of growth hormone states ____
Dual effector theory of growth hormone states growth hormone stimulates the differentiation of prechondrocytes and the local expression of IGF-1, which increases clonal expansion of chondrocytes
Glycoprotein hormones include ____, ____, ____, and ____
Glycoprotein hormones include TSH, FSH, LH, and HCG
Describe hypothalamic-pituitary-thyroid regulation
Hypothalamic-pituitary-thyroid regulation
Describe hypothalamic-pituitary-ovarian regulation
Hypothalamic-pituitary-ovarian regulation
Describe hypothalamic-pituitary-testicular regulation
Hypothalamic-pituitary-testicular regulation
Describe hypothalamic-pituitary-adrenal regulation
Hypothalamic-pituitary-adrenal regulation
Pro-opiomelanocortin necessitates ____
Pro-opiomelanocortin necessitates proteolytic processing
- Suppresses appetite
Vasopressin and oxytocin are synthesizes as ____
Vasopressin and oxytocin are synthesizes as precursor
Plasma vasopressin ____ as thirst increases
Plasma vasopressin increases as thirst increases
____ and ____ are principles regulating vasopressin secretion
Plasma volume and plasma osmolarity are principles regulating vasopressin secretion
Vasopressin ____ at physiologic (low) concentrations
Vasopressin reduces urinary water excretion at physiologic (low) concentrations
(antidiuretic)
- V2 receptors
Vasopressin ____ and ____ at pathologic (high) concentrations
Vasopressin increases release of Factor VIII and VWF at pathologic (high) concentrations
- V1 receptors
Vasopressin promotes insertion of _____ into luminal membrane, increasing _____ permeability
Vasopressin promotes insertion of Aquaporin 2 channels into luminal membrane, increasing water permeability
- Water passes through cell into interstitium driven by an osmotic gradient
Urine osmolarity ____ and urine flow _____ as plasma vasopressin increases
Urine osmolarity increases and urine flow decreases as plasma vasopressin increases
____ and ____ regulate oxytocin secretion
Suckling and cervical stretch receptors
Oxytocin causes ____ and ____
Oxytocin causes myoepithelial cell contraction and milk ejection
- Suckling is a major stimulus for oxytocin release
- Sensory receptors in nipple connect with nerve fibers to the spine -> impulses relayed through brain to PVN -> cholinergic synapses fire on oxytocin neurons and stimulate release
____ and ____ are hormones involved in childbirth
Estrogen and oxytocin are hormones involved in childbirth
- Positive feedback: contractions stimulate more contractions
