L02 - Intro to Hypothalamic-Pituitary Axis

Question 1

What connects pituitary gland and hypothalamus

Answer 1

Infundibulum

Question 2

What is posterior pituitary gland sometimes called

Answer 2

Neurohypophysis

Question 3

What hormones are secreted by posterior pituitary

Answer 3

ADH and oxytocin

Question 4

What are ADH and oxytocin synthesised by exactly? Transported? Stored?

Answer 4

Syn by Hypothalamus neurones: supraoptic nuclei and paraventricular nucleus

Transported via hypothalamiconeurohypophyseal tract

Stored in post pit

Question 5

What does ADH do? What happens at v high conc? Disorders?

Answer 5

v2 activation - translocation of AQ in kidney tubule. water absorption
v1 - very high - vasoconstriction

Disorders of fluid balance

Question 6

What does Oxytocin do?

Stimulation?

Answer 6

IP3 –> contaction of sm, muscle of genital tract (uterus) and breast

stim by genital and nipple stimulation.

Increases during pregnancy (with oxytocinase)

Parturition - uterus muscle contraction to expell infant. positive feedback with cervix stimulation

Lactation - suckling stimulates

Question 7

What hormones do the anterior pituitary gland secrete

Answer 7

Growth hormone
Prolactin
TSH
ACTH
FSH
LH

Question 8

In anterior pituitary gland, which cells produce which hormones?

Answer 8

Thyrotrope cells –> TSH
Corticotrope cells –> ACTH
Gonadotrope cells –> FSH

Question 9

What do releasing hormones travel in?

Answer 9

From hypothalamus to ant pit.

hypothalamicoADENOhypophyseal portal vessel.

Do not enter systemic circulation

Question 10

Diagnostic hormone tests

Answer 10

measuing releasing hormones and the effects of administering hormones - negative feedback

dinural rhythms - timing of tests is important

Question 11

What hormones can you measure

Answer 11

• TSH and FT4 (free non protein bound thyroxin)
• Cortisol
• LH and FSH
• Prl
• “Testosterone / Periods”

Question 12

How to test hypothalamus function

Answer 12

STimulate secretion - ACTH

SUPRESS secretion - Dexamethasone suppression

Question 13

What else can you test for after biochem tests? why and what for?

Answer 13

Imagine and visual field tests

Test for bilateral hemianopsia - enlargement of pit gland can compress optic chiasm

Question 14

Prolactin
Secreted by?
Controlled by?
Stimulated by?
Role?

Answer 14

Anterior pituitary - lactotrophe cells.

Hypothalamic control - Prolactin inhibiting factor - Dopamine.

TRH stimulates prolactin synthesis.

Stim by mild stress, nipple stimulation, coitus

Role - promote lactation and dev of breast tissue.

important after puberty. during and after pregnancy

Question 15

GROWTH HORMONE
Secreted by?
Controlled by?
Stimulated?
What else can it act as?
Effect?

Answer 15

Secr. by Anterior pituitary - SOMATOTROPHE cells

Controlled by Hypothalamus - GFRH and GFIH, somatostatin
——-GHRH more important

Stim by decreased FA & carb, increased amino acids

Can act as 2ary messenger in some tissues, produced by liver

Insulin like growth factor 1 & 2

Effect is to promote growth in adolescence by increased protein synthesis and collagen deposition. Also involved in tissue turnover and repair.