Hormone Synthesis and Action Flashcards
What hormones are synthesised by the hypothalamus?
ADH
oxytocin
What hormones are synthesised by the anterior pituitary gland?
ACTH GH FSH LH TSH
What hormones are synthesised by the posterior pituitary gland?
none
What hormones are synthesised by the thyroid?
triiodothyronine, T3
thyroxine, T4
calcitonin
What hormones are synthesised by the adrenal medulla?
adrenaline
noradrenaline
What hormones are synthesised by the adrenal cortex?
mineralcorticoids
glucocorticoids
androgens
What hormones are synthesised by the ovaries?
oestrogen
progesterone
What hormones are synthesised by the testes?
testosterone
What hormones are synthesised by the parathyroid glands?
PTH
What hormones are synthesised by the pineal gland?
melatonin
What hormones are synthesised by the Islets of Langerhans?
insulin
glucagon
somatostatin
Compare the endocrine and nervous systems in terms of:
- chemical coordinator
- speed of effect
- duration of effect
- localisation of effect
- hormone / neurotransmitter
- slow / fast
- longlasting / short-lived
- widespread (blood) / localised (NT secreted onto cell
What is the functional grouping of endocrine glands called?
Example?
The endocrine axis
e.g. hypothalamo-pituitary-adrenal axis
Describe the hypothalamic-pituitary axis in terms of the thyroid gland
- neurones in the hypothalamus secrete thyrotropin releasing hormone (TRH)
- stimulate anterior pituitary gland to released thyroid stimulating hormone (TSH)
- TSH binds to receptors on follicular cells of thyroid, stimulating synthesis and release of thyroid hormones
- both TRH and TSH are inhibited by negative feedback when blood concs of thyroid hormones increase
What are the 3 main groups of hormones?
peptide hormones
steroid hormones
amine hormones
Facts about peptide hormones
Made of chain of amino acids
Water soluble
Pre-prohormone –> prohormone –> hormone
Synthesis and secretion of peptide hormones
- transcription of gene
- pre mRNA
- splicing
- translation
- post-translational modification in golgi
- packaged in secretory granules
- exocytosis
Steroid hormone synthesis and secretion
- made from cholesterol
- synthesised de novo, in SER
- diffuses out of cell as lipid soluble
What is cholesterol converted into first? This is the rate limiting step.
Where does this take place?
Where does it then move to?
Pregnenolone
P formed in the mitochondria
Moves to SER for processing into hormone
What regulates the movement of cholesterol in mitochondria?
What regulates their activity and processing of cholesterol?
steroid acute regulatory protein
ACTH
What determines the course of pregnenolone?
Tissue specific and cell specific enzymes
How are steroid hormones excreted?
eliminated by liver/kidney by inactivating metabolic transformations and excretion in urine or bile
What are amine hormones?
What are they examples of?
Tyrosine derivatives bound together
Small, non polar, soluble in plasma membranes
T4, contains 4 iodine atoms
T3, contains 3 iodine atoms
Synthesis of T4 in the thyroid
- thyroglobulin synthesised in RER, exocytosed into colloid
- iodide pumped into cell
- iodide oxidised to iodine
- thyroglobulin iodinated
- In conjugation, adjacent tyrosyl residues are paired together
- complex reenters cell by endocytosis
- proteolysis liberates T3 and T4
