Hypothalamus & Pituitary Flashcards
List 6 hormones produced by the anterior pituitary.
prolactin,FSH,LH,ACTH, GH,TSH
List the hypothalamic releasing/inhibiting hormones and give their chemical nature&function
- Corticotrophin releasing hormone= 41 Amino acids
- Gonadotrophin releasing hormone= 10AA’s
- prolactin releasing hormone
- prolactin inhibitory factor= dopamine
- growth hormone releasing hormone=40/44 AA’s
- growth hormone release inhibiting hormone (somatostatin)= 14AA’S
- Thyrotropin releasing hormone=3AA’s
List the cell types present in the anterior pituitary
corticotroph, gonadotroph, lactotroph/mammotroph, somatotroph,thyrotroph
What is the role of portal vessels in the transport of trophic hormones?
Portal vessels carry trophic hormones directly to the anterior pituitary
What is the role of neurons in the transport of trophic hormones?
Neurons synthesizing trophic hormones release them into capillaries of the portal system
What is the role of endocrine cells in the transport of trophic hormones?
Endocrine cells release their hormones into the second set of capillaries for distribution to the rest of the body.
What are some of the actions of prolactin?
- In pregnancy promotes additional breast development and suppresses menstrual cycle
- Post-partum stimulates milk production
What can hyperprolactinaemia cause?
- galactorrhea-milk secretion from breast
- gynaecomastia-excess breast growth in males
- infertility in males& females
What treatments are available for hyperprolactinaemia?
Dopamine inhibits prolactin secretion via D2 receptors. So treatment involves D2 agonists cabergoline& bromocriptine
What are some of the actions of growth hormone
- growth of long bones until fusion of epiphyses
- increase in size of viscera
- anti-insulin effects
- metabolic effects related to growth
- anabolic for protein
- catabolic for fats and carbohydrates
What is the chemical structure of prolactin
198 AA’s
What is the chemical structure of GH
191 AA’s
What clinical conditions may result from hypersecretion of GH
- gigantism BEFORE fusion of the epiphyses
- acromegaly AFTER fusion of the epiphyses
What clinical conditions may result from hyposecretion of GH
- short stature BEFORE fusion of the epiphyses
- adult growth hormone deficiency AFTER fusion of the epiphyses
When are the most frequent episodic peaks of GH secretion?
At night time, when you are sleeping.
What treatments are available for acromegaly?
- Trans-sphenoidal surgery ( cos its usually due to a tumor)
- D2 agonists: bromocriptine/carbegoline
- long acting somatostatin analogues SSTR2 agonists: octrotride,lanreotide
- SSTR5 agonists agonist: pasireotide
What are the treatments available for small stature?
-treat with recombinant hGH (somatropin) or recombinant hIGF-1 (mecasermin)
What are the structural characteristics of posterior pituitary hormones?
- composed of 9 AA’s each and have two differences between them in their polypeptide chains
- synthesised with neurophysin as precursor in cell bodies in SON and PVN of hypothalamus
- associated with neurophysin I (oxytocin) or neurophysin II (arginine vasopressin =AVP/ADH)
- 80% SON neurons release AVP, PVN more diverse.
What are the actions of ADH?
Maintains BP via actions on….
- fluid balance: increased water re-absorption (V2)
- blood vessels: vasoconstriction (V1)
What are the actions of oxytocin?
- Uterus: causes contraction
- Mammary gland: milk ejection
- LOVE HORMONE( responsible for human behaviors associated with relationships and bonding.)
- Most commonly used to help mothers produce contractions in labor and control bleeding
- Positive feedback mechanism
Which hormones are stored and released by the posterior pituitary
Oxytocin& ADH
What is the function of aromatase
- An enzyme that converts androgens into oestrogens
- Aromatase is mainly produced by fatty tissue
What properties do insulin & GH share
- Protein anabolic properties
- Other than that they pretty much have opposite effects
