Hypothalamus & Pituitary Flashcards
(22 cards)
What are majority cells in anterior pituitary
Somatotrophs making growth hormone
How does hypothalamus control growth hormone
and prolactin
TRH for thyroid hormone also encourages release of prolactin. Dopamine discourages.
GNRH and somatostatin encourage release and stop release of growth hormone respectively
What is a tropic hormone
goes to other cells to cause release of hormone there
Which are the two nontropic hormones of the anterior pituitary
MSH and prolactin (don’t cause release of another hormone)
Role of LH and FSH in males
LH - testosterone secretion in Leydig cells. Testosterone feeds back and stops further production of GnRH which releases FSH and LH.
FSH helps spermatogenesis in Sertoli cells - inhibin prevents further action via negative feedback.
Outline control of prolactin release in females (2)
Suckling activates mechanoreceptors, which feedback to hypothalamus and a) INHIBIT dopamine release in hypothalamus, so prolactin is produces, acts on milk gland cells and syntheses milk and b) OXYTOCIN is released, acting on myoepithelial cells around ducts, causing milk ejection
What is hyperprolactinaemia and what’s the treatment for it
Galactorrea (producing milk even when not pregnant in females) and gynacomastia in males and females (breast growth).
treatment - d2 agonist, activate dopamine which inhibits prolactin
What’s the use of prolactin in new mothers
Suppresses menstrual cycle so she won’t become pregnant whilst nursing newborn child
How does growth hormone act
can act directly on tissues that have a receptor for it to then stimulate gene transcription, and also on insulin growth like factor
Function of growth hormone (3)
mobilize glucose when it’s low, increase size of viscera, growth of long bones until epiphyseal plates fuse
Treatment for acromegaly
D2 agonist because tumours usually have D2 receptors, not because dopamine usually affects growth hormone. can also use somatostatin - lanreotide, pasireotide
How can we spot acromegaly based on levels of growth hormone on graph
don’t have pulsatile release, don’t get increase in sleeping time whereas normally GH is undetectable and is only high during sleep time
Does growth hormone make you taller
No, it accelerates the speed at which you would’ve reached your maximum height
Roles of oxytocin
Milk ejection, during labour - uterine smooth muscle develops receptors for it so helps contraction to give birth to baby. Also role in social behaviour
DIfference in hormone release between anterior/posterior pituitary
Anterior: neurosecretory cells release hormone into portal vein, travels down to anterior pituitary, down portal circulation.
posterior: neurosecretory cells have endings in posterior pituitary so release contents directly into portal vein
What does MSH do
stimulate melanocytes in skin and hair
How is hormone production controlled in males
GnRH –> LH & FSH –> testosterone & inhibin –> -ve feedback
Outline how release of growth hormone is controlled
GnRH –> stimulates GH release which then stimulates release of insulin growth like factor from liver and other tissues and this causes growth. Somatostatin inhibits this
4 physiological factors that stimulate growth hormone secretion
exercise, sleep, stress, postprandial glucose decline
Pharmacological factors that encourage growth hormone secretion (2)
amino acid infusion, drug induced hypoglycaemia
What are lanreotide, pasireotide for
Treating acromegaly because somatostatins inhibit GH release, good if person not eligible for trans-sphenoidal surgery
Acromegaly causes increase in what kind of tissue
soft
