corticosteroids Flashcards
hormones the hypothalamus secretes
oxytocin antidiuretic hormone (ADH)
Where are hypothalamus hormones stored?
in the posterior pituitary
What does the hypothalamus do to the posterior pituitary?
directs it to release hormones
What is the pituitary gland controlled by?
hypothalamus
What is the pituitary gland protected by?
sella turcica (bony structure)
What is located above the pituitary gland?
the optic chiasm
What does the optic chiasm do?
carries visual information to the brain for interpretation
2 lobes of the pituitary
anterior lobe
posterior lobe
What hormones does the pituitary secrete?
GH luteinizing hormone adrenocorticotropic hormone (ACTH) prolactin thyroid-stimulating hormone (TSH) follicle-stimulating hormone
What does GH do?
stimulates increase in size of muscles and bones
What does leutinizing hormone do?
females - stimulates ovulation and oestrogen production
males - stimulates testosterone production
What does adrenocorticotropic hormone do?
stimulates the adrenal cortex to release its hormones
What does prolactin do?
stimulates milk production from the mammary glands
What does thyroid stimulating hormone do?
stimulates the thyroid gland to release its hormones
What does FSH do?
females - stimulates oestrogen production and maturation of the ova
males - stimulates sperm production
Where does ACTH work?
adrenal cortex
Where does GH work?
bones and muscles
weight of the human adrenals?
8 - 10g
composition of the adrenal gland
- outer cortex with 3 zones (reticularis, fasciculata and glomerulosa), produce steroids
- inner medulla that synthesises/stores/secretes catecholamines
What system acts on the adrenal medulla?
sympathetic nervous system
What does the adrenal medulla secrete?
adrenaline and noradrenaline
What does the release of adrenaline cause?
vasodilation
tachycardia
insulin resistance
What does the release of noradrenaline cause?
vasoconstriction
What hormone from the pituitary acts on the zonae fasciculata and reticularis?
ACTH
What do the zonae fasciculata and reticularis secrete?
androgens
cortisol
What are androgens responsible for?
pubic hair and libido
What is cortisol responsible for?
metabolic regulation
immunomodulation
cardiovascular regulation
CNS actions
What does the zona glomerulosa secrete?
mineralocorticoids
What do mineralocorticoids do?
increase BP
Na retention
K wasting
metabolic alkalosis
daily secretions of cortisol
5 - 30mg
daily secretions of corticosterone
2 - 5mg
daily secretions of aldosterone (mineralocorticoids)
5 - 150mcg
androgen hormone? and daily secretions?
DHEA
15 - 30mg
progestogen hormone and daily secretions?
progesterone
0.4 - 0.8mg
oestrogen hormone and daily secretions?
oestradiol
trace amounts
symptoms of Cushing’s syndrome?
euphoria buffalo hump thinning of skin thin arms/legs intracranial hpt moon face, red cheeks increased abdominal fat easy bruising poor wound healing osteoporosis increased appetite obesity increased susceptibility to infection
What is cholesterol the precursor of?
vitamin D and bile acids
How are steroid hormones bound in the blood?
to carriers
name of the steroid carrier
CBG corticosteroid binding globulin
Advantages of steroids being bound when in the blood
enzymatic degradation
extended half life
How is the half life of steroids extended when bound to carriers?
it blocks their entry into target cells because carrier proteins are liphopholic and can’t diffuse through the cell membrane
What do steroids bind to in the target cell?
region in DNA called GRE (glucocorticoid response element)
M/A of steroid when it diffuses into target cell
- unbound hormone binds to cytoplasmic receptor
- goes to nucleus where it binds to region in DNA called GRE (glucocorticoid response element)
- interaction of steroid and GRE activated gene transcription
- mRNA produced
- mRNA moves to cytoplasm
- translation produces new proteins for cell processes and alters protein synthesis to produce a biologic effect
When are the highest/lowest levels of cortisol secretion?
highest - morning on waking
lowest - midnight
