2. Into to HPA

Question 1

where is the pituitary located?

Answer 1

area of brain directly below hypothalamus
connected to the brain by the infundibulum
divided into anterior and posterior portions

Question 2

what does the posterior pituitary gland secrete?

Answer 2

secretes ADH, oxytocin (peptide hormones)
peptide hormones
synthesised by neurons of the hypothalamus as inactive precursors
converted to active form in posterior pituitary

Question 3

what is the hypothalamico-neurohypophyseal tract?

Answer 3

tract connecting hypothalamus and posterior pituitary gland

inactive hormones transported to pituitary

Question 4

posterior pituitary gland

Answer 4

stores inactive hormones, prepares them for release

Question 5

antidiuretic hormone

Answer 5

secretion is influenced by plasma osmolarity
stimulation of v2 receptors causes translocation of aquaporins to membrane of the kidney tubule - water reabsorption
stimulation of v1 receptors causes vasoconstriction (not in physiological concentrations)

Question 6

oxytocin

Answer 6

acts via IP3 to cause contraction of smooth muscle of breast and uterus
secretion is stimulated by stimulation of genitals/nipples
synthesis increases during pregnancy (+ increase in oxytocinase)
most important during pregnancy/lactation
can be administered to induce labour

Question 7

anterior pituitary gland

Answer 7

more complicated than posterior physiology

up-growth from the plate

Question 8

what does the anterior pituitary gland secrete?

Answer 8

growth hormone
prolactin 
thyroid stimulating hormone (TSH)
adrenocorticotrophic hormone (ACTH)
follicle stimulating hormone (FSH)
luteinising hormone (LH)

Question 9

what is the hypothalamico-adenohypophyseal portal vessel?

Answer 9

tract along which hypothalamus secretes releasing hormones to control anterior pituitary secretions
not connected to systemic circulation

Question 10

what types of cells are there in the anterior pituitary gland?

Answer 10

thyrotrophe cells - TSH 
corticotrophe - ACTH 
gonadotrophe - FSH
somatotrophe - GH
lactotrophe  - prolactin

Question 11

clinical investigations

Answer 11

start with signs and symptoms
follow with biochemical tests
follow with imaging (MRI)
after imaging, visual field test

Question 12

what can be measured?

Answer 12

TSH, FT4
cortisol 
LH and FSH
prolactin 
testosterone, 'periods'

Question 13

prolactin

Answer 13

peptide hormone
synthesised in somatotrophe cells
secretion under hypothalamic control
promotes lactation and breast tissue development

Question 14

how does the hypothalamus control prolactin secretion?

Answer 14

prolactin release inhibiting factor = dopamine
suppresses prolactin synthesis
TRH stimulates synthesis

Question 15

how is prolactin secretion stimulated?

Answer 15

mild stress
nipple stimulation
coitus

Question 16

growth hormone

Answer 16

synthesised in somatotrophe cells
secretion controlled by hypothalamus
primary effect = promote linear growth in adolescence
increases protein synthesis and collagen deposition, mediated by nucleus
foetal growth relatively independent
involved in tissue turnover and repair
can act as second messenger in some tissues - produced in liver (insulin like growth factor 1/2)

Question 17

how does the hypothalamus control growth hormone secretion?

Answer 17

growth hormone releasing hormone (GHRH) - more important

growth hormone release inhibiting hormone (GHRIH, somatostatin)

Question 18

how is growth hormone secretion stimulated?

Answer 18

decreased carbohydrates and fatty acids

increased amino acids