ESR. 002. Hypothalamo-pituitary complex

Question 1

what type of projection go to the posterior pituitary

Answer 1

axonal projections from key nuclei in the hypothlamus

Question 2

what type of projection go to the anterior pituitary

Answer 2

chemical projections via fenestrated capillaries

Question 3

where is the pituitary gland situated

Answer 3

in the sphenoid bone
under the optic chiasm
above the roof of the mouth
third ventricle sits above

Question 4

what connects the hypothalamus to the pituitary gland

Answer 4

pituitary stalk

Question 5

what part of the pituitary gland makes up the majority its mass

Answer 5

anterior pituitary

Question 6

describe the embryoligical development of the gland

Answer 6

posterior pitutiary - down growth of neural tissue (diencephalon)
anterior pituitary - upgrowth of Rathkes pouch (roof of mouth)

Question 7

what hormones travel from hypothalamus to posterior pituitary

Answer 7

oxytocin and ADH - made by neurones in hypothalamus

Question 8

what nuclei are found in the hypothalamus that make post pit hormones

Answer 8

PVN, supraoptic, suprachiasmatic

Question 9

what is the name of the tract that carried the hormones to post pit

Answer 9

hypothalamis-hypophyseal tract ( via the infundibulum)

Question 10

which artery picks up the hormones from the post pit

Answer 10

inferior hypophyseal artery

Question 11

what is the name of the protein that carries the hormones to the post pit

Answer 11

neurophysins

Question 12

where are neuropeptides formed that go to ant pit

Answer 12

primary capillary plexus in the hypothalamus

Question 13

what is the name of the tract that carried the hormones to ant pit

Answer 13

hypophyseal portal system

Question 14

what makes up the majority of the ant pit

Answer 14

pars distalis

Question 15

what three cell types are found in the pars distalis

Answer 15

acidophils - stain red or orange
basophils - stain blue
chromophobe - do not stain

Question 16

what do acidophils produce

Answer 16

polypeptide hormones
somatoropes - make GH
lactotropes - make prolactin

Question 17

what do basophils produce

Answer 17

glycoprotein hormones
thyrotropes - TSH
gonadotropes - LH, FSH
corticoropes - ACTH

Question 18

what do chromophobes produce

Answer 18

nothing

Question 19

what is the action of TSH

Answer 19

synthesis and secretion of thyroid hormones

Question 20

action of gonadotrophs LH and FSH

Answer 20

steroid biosynthesis and germ cell maturation

Question 21

action of ACTH

Answer 21

steroid biosynthesis in adrenal cortex

Question 22

action of GH

Answer 22

growth via insulin like growth factor IGF-1 (in the liver)

Question 23

action of prolactin

Answer 23

lactation

Question 24

what is the general structure of TSH, LH and FSH

Answer 24

heterodimeric glycoproteins
common alpha subunit
each has a specific beta subunit

Question 25

what is the structure of ACTH

Answer 25

39aa fragment of POMC | POMC also makes melanocortisone skin pigment and endorphins in the same process

Question 26

what is the general structure of GH and prolactin

Answer 26

190aa peptides internal di-sulfide bonds they have homologous receptors

Question 27

what is the pars intermedia

Answer 27

the intermediate lobe between the anterior and posterior lobe closely associated with pars nervose and separated from the pars distalis by the hypophyseal cleft

Question 28

what is the function of the intermediate lobe

Answer 28

very little function in humans | secretes melanocyte stimulating hormone?

Question 29

where are the anterior pituitary releasing/inhibiyory hormones released to to reach there

Answer 29

the median eminence of the third ventricle

Question 30

what receptor do hypothalamic releasing hormones act on

Answer 30

GPCR - AC-cAMP-PKA-CREB pathway for CRH and GHRH - Ca2+/PLC pathway for GnRH and TRH

Question 31

how is prolactin release controlled

Answer 31

under dominant negative control by dopamine (from arcuate nucleus)

Question 32

how does pituitary stalk damage affect prolactin secretion

Answer 32

will increase prolactin secretion in women we see increased prolactin and increased lactation sex drive change increased breast tissue

Question 33

how can functional disconnection of pituitary gland occur

Answer 33

``` cranial trauma pituitary tumour inflammation midline defects eg septo-optic dysplasia defects in migration of hypothalamic neurones eg Kallmans syndrome ```

Question 34

how can hyposecretion of anterior pituitary hormones

Answer 34

adenohypophyseal cells sensitive to irradiation - particularly the somatotrophs

Question 35

what is the most common functional pituitary tumour

Answer 35

prolactinoma - causes galactorrhea - infertility due to suppression of the HPG axis

Question 36

what is Cushings disease caused by

Answer 36

ACTH - hypersecretion from pituitary corticotrophs or ectopic - from small cell lung tumours

Question 37

how many amino acids make up oxytocin

Answer 37

9

Question 38

what are the cellular actions of oxytocin on the boob

Answer 38

stimulation of milk ejection | target myoepithelial smooth muscle cells around alveoli of mamillary gland

Question 39

what are the cellular actions of oxytocin on the uterus

Answer 39

stimulate uterine smooth muscle contractions at birth during late gestation get an increase in oxytocin receptors in uterine smooth muscles (causes irritability) positive feedback nb - fergusson reflex

Question 40

what are the actions of oxytocin on maternal behaviour

Answer 40

nurturing attachment to baby