Hypothalamus and pituitary

Question 1

What are the sections of the adenohypophysis

Answer 1

pars distalis

pars tuberalis

Question 2

What are the sections of the neurohypophysis

Answer 2

pars nervosa

infundibulum

Question 3

What are the cell types in the adenohypophysis and what do they secrete

Answer 3

Corticotrophs = ACTH (adrenocorticotropic hormone)
Gonadotrophs = FSH (follicle stimulating hormone) + LH (lutenizing hormone)
Lactotrophs = Prolactin
Somatotrophs = GH 
Thyrotrophs = thyroid stimulating hormone (TSH)

Question 4

How is oestrogen production controlled in females?

Answer 4

FSH and LH are released from the ant. pituitary.

Graffian follicles (from which oestrogens are released) are matured into corpus luteum (from which both oestrogens and progesterone are released).

Oestrogen then feeds back to inhibit the ant. pituitary release of TSH and LH.

Progesterone feeds back to the ant. pituitary to inhibit the release of TSH and LH, but also the hypothalamus to inhibit the release of GnRH

Question 5

How is testosterone production controlled in males?

Answer 5

FSH and LH are released from the ant pituitary.

Leydig cells then release testosterone which feeds back to the ant. pituitary

Question 6

What structure in the cell becomes matured in the process of producing oestrogens and progesterone in the female?

Answer 6

Graffian follicles mature into the corpus luteum

Graffian follicles release oestrogen
Corpi luteum release oestrogen and progesterone

Question 7

What hormones control the release of prolactin?

Answer 7

Inhibitory:
prolactin inhibition factor (PIF)
dopamine (D2)

Excitatory:
prolactin releasing hormone (PRH)
thyrotropin releasing hormone (TRH)

Question 8

How does dopamine inhibit prolactin release?

Answer 8

Hypothalamus released dopamine, which travels down the pituitary stalk inhibiting the release of prolactin from the ant. pituitary

Question 9

How is prolactin release controlled?

Answer 9

The anterior pituitary releases prolactin and the posterior pituitary releases oxytocin.

Prolactin causes milk gland cells in the breasts to produce milk.
Oxytocin causes contraction of myoepithelial cells therefore causing milk ejection.

Suckling of a child stimulates nipple mechanoreceptors which cause the inhibition of the release of dopamine (inhibitory to PRL release) from the hypothalamus therefore increaseing PRL release. Also mechanoreceptor stimulation causes an increase in the release of oxytocin via stimulating the release of oxytocin releasing factors in the hypothalamus. (so basically the mechanoreceptors promote the production/release of milk via feedback to the hypothalamus)

Question 10

What is hyperprolactinaemia?

Answer 10

High prolactin levels causing galactorrhoea, gynaecomastia, infertility in both males and females.

Prolactin supresses the menstrual cycle leading to infertility in females.

Question 11

How can hyperprolactinaemia be treated?

Answer 11

As dopamine released from the hypothalamus inhibits prolactin release, D2 agonists are used as treatment such as:

bromocriptine + cabergoline

Question 12

What can hypersecretion of GH cause?

Answer 12

Gigantism before/after fusion of epiphyses

Question 13

What can hyposecreteion of GH cause?

Answer 13

Short stature before fusion of epiphyses

Adult GH deficiency after fusion of epiphyses

Question 14

How can acromegaly be treated?

Answer 14

Trans-sphenoidal surgery
D2 agonists such as bromocriptine/carbegoline
somatostatin such as octreotride,
lanreotide (SST2>SST5), pasireotide (SST5>SST2)

Question 15

What somatostatins can be given to treat acromegaly?

Answer 15

Octreotide
Lanreotide (SST2>SST5)
Pasireotide (SST5>SST2)

Question 16

Where are posterior pituitary hormones made?

Answer 16

Supraoptic nucleus (SON) and paraventricular nucleus (PVN)

SON produces ADH (arginine vasopressin, ADP), PVN is more diverse.