steroid biosynthesis Flashcards
Progestins
progesteron
synthesized in adrenal glands, ovaries, testes
distributed to uterus
mediates implantation and maintenance of pregnancy
Glucocorticoids
cortisol cortisone, corticosterone
synthesized in adrenal glands, distributed to a large number of tissues and organs (muscle, liver)
increases blood pressure and Na uptake in kidneys
mediates response to stress by increasing protein catabolism and gluconeogenesis and reducing inflammation
mineralocorticoids
aldosterone
11 deoxycorticosterone
made in adrenals, distributed to kidney tubules, colon, and parotid gland, increases Na/H20 retention, K excretion and blood pressure
Estrogens
estradiol and estrone
made in ovaries (major), placenta, adipise tissue
distributed to primary and secondary reproductive organs
mediates feminization, estrous cycle
Lypophilic signal molecules
steroid hormones:
progesterone, estradiol, testosterone, cortisol, aldoesterone, vitamine D
theyroid hormone– thyroxine
retinoids, retinol, retinoic acid
small lipophilic molecules = steroids
i am a peptide that activates expression of desmolase
ACTH: adrenocorticotopic hormone
secreted during stressful situation like hypoglycemia, cold, and exercise
from pituitary gland but turned on by corticotropin releasing hormone from hypothalamus
hypothalamus –> cotricotropin releasing hormone —> pituitary —> ACTH —-> adrenals —> cortisol release
i am a peptide that increases activity of desmolase
LH
hypothalamus –> GnRH –> Pituitary –> LH —> desmolase stimulation of activity
i am a peptide that actives the enzyme aromatase
FSH
promotes spermatogenesis in men
stimulates menstruation in women
Someone is suffering from hypertension and low cortisol
what enzyme is effected
11-beta-hydroxylase, active in both aldosterone and cortisol production pws
Someone is suffering from a loss of sex steroids AND cortisol
what enzyme is affected
17-alpha-hydroxylase
someone is suffering a defect in 3 beta hydroxysteroid dehydrogenase, which lipophilic compounds are prevented from being synthesized?
all of them EXCEPT FOR ESTRONE
aldosterone
promotes na/h2o retention
reduced levels = too much salt
excessive levels = conn syndrome, increased blood volume, hypertension
cortisol
also known as hydrocotisone
anti inflammatory and autoimmune properties
stimulates breakdown ofm uscle, gluconeogenesis and glycogen synthesis
Conn syndrome
elevated levels of aldosterone, increased blood volume and hypertension follow
Cushing syndrome
elevated levels of cortisone
increased fat on face and trunk
can be caused by tumors in the pituitary or adrenal tumors or too much administration of cortiosteroids
effects ACTH feedback system
glucocorticoids and immune functioning
like cortisol
inhibits immune system by inducing i-kbalpha inhibitory protein. necessary for IL-2 synthesis, so decreased clonal expansion of B lymphocytes
promotes T cell apoptosis
inhibits both humoral and adaptive branches
mineralcorticoids target tissues….
kidneys, colon, parotid gland
contain a receptor that has equal affinity for mineral as glucocorticoids
because they want to avoid Na/Water retention, they must metabolize cortisol further via 3-beta-hydroxysteroid dehydrogenase
Cortisol
has affinity for minteralcorticoid receptors 100 time ore concentral than mineralcorticoids, so target tissues further metabolize it to cortisone, a compound with a much less affinity
REAL LICORICE CAN LEAD TO HYPERTENSION BECAUSE IT INHIBITS 3-beta-HYDROXYSTEROID DEHYDROGENASE
Vitamin D
the effects are attributed to its
active form: calcitriol
Vit D2
ergocalciferol
Vit D3
cholcalciferol
where are VD3 and VD2 found?
fish, eggs, plants, vitamin d fortified foods
Vit D is produced
through diet or through UV rays
Calcitriol
active form of VD, derived from VD2 and VD3
also known as 1,25-dihydroxycholcalciferol
V D deficiencies related to
lung diseases, autoimmune diseases, malabsorption, cancer, infections, mental sickness
osteomalacia, rickets, bone stuff
cholcalciferol
cholecalciferol inactive form of VD3
derived from 7-dehydrocholesterol via UV irradiation in the skin
in intestinal cells from ergocalciferol (Vit D2)
7-dehydrocholesterol
produced in skin
UV rays break B ring —> cholecalciferol
ergocalciferol
in intestinal cells, Vit D2 —> cholecalciferol
25 hydroxylase
in liver it hydroxylates cholecalciferol D3 to 25-hydroxycholecalciferol
1-alpha-hydroxylase
in the kidneys this enzymes converts 25 hydroxycholecalciferol to 1,25 dihydroxycholecalciferol
calcitriol in the body?
stimulates intestine to absorb calcium and phosphate
increases kidney absorption, promotes calcium resorption from the bone
resulting effect is an elevation in blood Ca and phosphate levels
PTH and calcitonin are peptide signals
common inherited defect that leads to salt wasting, hypotension, hyperglycemia due to INCREASED PRODUCTION of cortisol.
causes virilism in women due to increased flow of intermediates into adrenal androgens
21-hydroxylase
11 beta hydroxylase deficiency
hypertension due to increased accumulation of 11 deoxycorticosterone
