6 hypothalamus and pituitary hormones Flashcards
hormones of anterior pituitary, and cells:
- somatatrophs-> somatatropin-> GH
- lactotrophs-> prolactin
- corticotrophs-> corticotropin-> ACTH
- thyrotrophs-> thyrotropin-> TSH
- gonadatrophs-> gonadatrophin -> LH, FSH
characteristic of GH and prolactin
single chain polypeptide with disulphide bridges
characteristic of ACTH
small peptide
characteristic of TSH, LH and FSH
glycoprotein with two subunits
what type of hormones are the ones released by anterior pituitary. which is the hormone that isn’t characterised by this?
tropic hormones= have other endocrine glands as target
prolactin is not a tropic hormone
what are the nuclei in hypothalamus effecting anterior pituitary?
what type of neuroendocrine hormones are released?
arcuate nucleus: GnRH and GHRH (LH, FSH and GH). dopamine
preoptic nucleus: GnRH
paraventricular nucleus: CRH (cortisol), TRH (thryoid hormones), somatostatin
releasing factors pass through hypohyseal portal vessels to reach capillary bed of adenohypophysis
prolactin actions
- stimulates mammary glands to produce milk (lactation)
- promotes growth and development of breasts
High [prolactin] inhibit GnRH release (gonadotrophins)
actions of growth hormone
linear growth
metabolism
actions of ACTH: adrenocorticotropic hormone
what is it synthesised from
Stimulates synthesis/ release of cortisol. A small peptide
synthesised from large precursor glycoprotein pro-opiomelanocortin (POMC)
- Undergoes post translational processing which is tissue specific (in ant. pituitary it is cleaved to ACTH)
actions of LH
ovaries & testes (Leydig cells- testosterone)– stimulates steroid hormone synthesis
(f : causes ovulation/ formation of corpus luteum)
action of FSH
ovaries – stimulate follicular development
testes (Sertoli cells) – spermatogenesis
what are the nuclei in hypothalamus that effect posterior pituitary?
paraventricular nucleus: oxytocin and small amount of vasopressin
supraoptic nucleus: cell bodies produce vasopressin
hormones of posterior pituitary
- arginine vasopressin (AVP) (or ADH)
- oxytocin
AVP
- stimulations
- actions
- Stimulated by increase in body fluid osmolality,
fall in blood volume/ pressure, and stress
Actions:
- Blood vessels – vasoconstriction, via V1 receptors (at higher [AVP])
- Kidney (distal convoluted tubules and collecting ducts)- increase permeability and hence re-absorption of water. Via V2-receptors
- Also, stimulate ACTH release (deal with stress)
stimulation of oxytocin
actions
clinical use
Release stimulated by suckling, and by cervical stimulation (parturition)
release is via positive feedback
- Stimulate “milk let-down”, expression of breast milk
- Uterine smooth muscle - contraction
- Maternal behaviour / sexual behaviour/ social bonding ?
- Attachment: oxytocin and vasopressin in feeling of attachment long enough to have children
Clinical use: enhancement and induce labour
