Hypothalamic Pituitary Target Tissue Axis Flashcards
Vascularized (lots of blood flow) region
Median eminence
Region where nerve fibers from each eye cross to opposite half of the brain
Optic chiasm
Provides local delivery of substances at high concentration
Hypothalamic-hypophysial portal system
Adenohypophysis
Anterior pituitary
Neurohypophysis
Posterior pituitary
Which cell produces thyroid stimulation hormone (TSH)?
Thyrotroph
Which cell produces luteinizing and follicle stimulating hormone?
Gonadotrophs
Which cell produces adrenocorticotropic hormone (ACTH)?
Corticotrophs
Which cell produces growth hormone?
Somatotroph
Which cell produces prolactin (PRL)?
Lactotroph
All anterior pituitary hormones are…
Peptides/proteins
Hormones in the somatoomammotropin family of the anterior pituitary
- Growth hormone
- Prolactin
Growth hormone
Stimulates growth (via insulin-like growth factor-1; IGF-1) and affects metabolism
Prolactin
Stimulates milk synthesis and secretion during lactation
Hormones in the glycoprotein family of the anterior pituitary
- Follicle stimulating hormone
- Luteinizing hormone
- Thyroid stimulating hormone
Follicle stimulating hormone
- Stimulates follicular growth and estrogen
production in ovaries - Regulates spermatogenesis in testes
Luteinizing hormone
- Regulates estrogen and progesterone production
in ovaries and luteinization of follicle - Regulates testosterone production in testes
Thyroid stimulating hormone
Stimulates synthesis and secretion of thyroid hormone (T 3 and T 4) by thyroid gland
Hormones in the pro-opiomelanocortin (POMC) family of the anterior pituitary
- Adrenocorticotropic hormone
Adrenocorticotropic hormone
Stimulates synthesis and secretion of cortisol and DHEA (a weak androgen) by adrenal cortex
If a patient had a disease that damaged the corticotropes, which organ would be most affected?
Adrenal glands
AP hormones are synthesized…
on the endoplasmic reticulum
AP hormones are modified…
in the Golgi apparatus
AP hormones are stored…
In vesicles until they are needed
A patient has an ACTH secreting tumor, which causes ACTH to be elevated. You would expect to see a _______ in CRH secretion.
- Decline
- High levels of ACTH can increase cortisol and aldosterone stimulating negative feedback.
Releasing hormones
- Growth hormone releasing hormone (GHRH)
- Thyrotropin releasing hormone (TRH)
- Gonadotropin releasing hormone (GnRH)
- Corticotropin releasing hormone (CRH)
Growth hormone releasing hormone (GHRH)
Stimulates GH synthesis & secretion
Thyrotropin releasing hormone (TRH)
Stimulates TSH synthesis & secretion
Gonadotropin releasing hormone (GnRH)
Stimulates LH and FSH synthesis & secretion
Corticotropin releasing hormone (CRH)
Stimulates ACTH synthesis & secretion
If two hormones have similar structures…
A high enough amount can trigger the other hormones receptors
Inhibiting hormones
- Growth hormone inhibiting hormone (GHIH)
- Prolactin inhibiting hormone; dopamine (PIH)
Growth hormone inhibiting hormone
- Peptide
- Inhibits GH synthesis and secretion
Prolactin inhibiting hormone (PIH); dopamine
- Catecholamine
- Inhibits PRL synthesis and secretion
LH secreted by the anterior pituitary acts on…
the testis
GnRH secreted by the hypothalamus acts on…
gonadotropes in the anterior pituitary
If a patient has a lesion in the paraventricular nucleus, you would expect to see…
- a decline in CRH
- Could be a decline in OT however the supraoptic nucleus also produced OT so it wouldn’t be much
Hormones of the paraventricular nucleus
- TRH
- CRH
- OT
- ADH/VR
Hormones of the preoptic area
- GnRH
Hormones of the supraoptic nucleus
- OT
- ADH/VP
Hormones of the arcuate nucleus
- GHRH
- GnRH
- GHIH
- PIH
Hormones of the ventromedial nucleus
- GHRH
- GHIH
Primary function is to regulate hormone secretion by another endocrine gland
Tropic hormone
Primary effect is on non-endocrine target tissues
Non-tropic hormone
Negative feedback loop
Response of target cell dampens or inhibits initial stimulus
Positive feedback loop
Response of target cell stimulates or enhances initial stimulus
Posterior pituitary hormones
- Oxytocin
- Antidiuretic hormone (ADH); vasopressin (VP)
Oxytocin
- Stimulates smooth muscle contraction
- Breast myoepithelial cells during lactation (milk
ejection) - Uterine myometrium during labor
Antidiuretic hormone
- Stimulates water reabsorption by kidney
- Stimulates arteriole constriction