Introduction to Endocrinology Flashcards
Define Endocrinology
The study of hormones (and gland of origin), their receptors, intracellular signalling pathways and associated disease
Define Paracrine
Acts on adjacent cells
Define Autocrine
Feedback on same cell that secreted hormone
What form of Iodotyrosine is most active
T3
What are thyroid hormones bound to
TBG (Thyroid-Binding Globulin)
Where are thyroid hormones stored
In colloids bound to thyroglobulin
How does Dopamine effect the release of prolactin
Inhibits the release of prolactin
What would happen to prolactin levels if the infundibulum of the pituitary gland was destroyed
Prolactin levels would increase
Does the anterior pituitary gland have an arterial blood supply
Nope
Blood supply of the anterior pituitary gland
Hypothalamus-hypophyseal portal veins
What is the benefit of the hypothalamus-hypophyseal portal veins
Provides a mechanism for hormones of the hypothalamus to directly alter the activity of cells of the anterior pituitary gland by bypassing circulation
What is the benefit of the hypothalamic-pituitary axis
Allows for an amplified response
What cells produce FSH and LH
Gonadotrophs
What cells produce ACTH
Corticotrophins
What cell secrets TSH
Thyrotrophs
Where is prolactin produced
Lactotrophs
Where is GH produced
Somatotrophs
F: FSH L: LH A: ACTH T: TSH P: Prolactin I: Ignore G: GH
What does FSH and LH target
Gonads
What does LH and FSH stimulate together
Germ cell development
What does FSH exclusively stimulate
Release of oestrogen
What does the release of oestrogen stimulate
Release of LH
Role of LH
Stimulates the release of the egg which stimulates progesterone release
Role of progesterone
Results in increased thickening of the uterine wall
How does LH effect males
On leydig cells - testosterone release
How does GH effect an individual
Growth and protein synthesis
How does GH effect blood glucose levels
Increases:
Causes gluconeogenesis
Inhibits Insulin
Lipolysis
Role of GH on the liver
Increases protein synthesis and stimulates production of IGF-1 which acts on skeletons to increase cartilage proliferation
What compound is IGF-1 similar to
Insulin
Role of IGF-1
Basically GH’s servant. It is produced by liver and stimulates body growth in every cell of the body
Where is ACTH produced
Anterior Pituitary Gland
Role of ACTH
Stimulates adrenal cortex to secrete cortisol from zona fasiculata , androgens from zona reticular and adrenaline from adrenal medulla
Where is dopamine produced
Hypothalamus
Does a negative feedback loop exist for prolactin
No, because of the role of Dopamine
Prolactin acts on the hypothalamus to cause the release of dopamine
What happens when GH binds to the hypothalamus
GH causes secretion of somatostatin which is inhibitory
Where is Vasopressin produced
Supraoptic nucleus of the hypothalamus
Where is Oxytocin produced
Paraventricular body
Describe the pathway of from the supraoptic and paraventricular nuclei
Moves down the infundibulum and terminates in posterior pituitary gland
Where are Vasopressin and oxytocin stored
In vesicles and accumulate in axon terminal in the posterior pituitary glands
How does ACTH cause fluid retention
ACTH causes release of aldosterone which causes up regulation of Na+/K+ pumps (3 Na out for 2K in)
Role of Oxytocin in breast milk
Needed for ejection of milk by myoepithelial cells
Role of oxytocin during pregnancy
Stimulates contraction of uterine smooth muscles until baby is born and labour
What is the consequence of oxytocin having a short half-life
More has to be produced on a minute-by-minute basis
What type of receptors do ALL pituitary and hypothalamic hormones act on
G-protein couples receptors
