Where does steroid synthesis occur?
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In the mitochondria and endoplasmic reticulum (ER).
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Where does steroid synthesis occur?
In the mitochondria and endoplasmic reticulum (ER).
Where does synthesis and secretion occur in the body?
In the adrenal cortex.
What happens in CYP 17 deficiency?
Lack of production of cortisol and androgens. Overproduction of aldosteron.
What happens in enzyme deficiency of CYP 11?
buildup of aldosterone precursor which inappropriately binds aldosterone receptor leading to hypertension. Since cortisol is not produced, there is no negative feedback leading to prolonged HTN.
What are the building blocks formed from Mevalonate?
Isoprene/terpene units.
What is the initial rate-limiting reaction in steroid synthesis?
Cholesterol → Pregnenolone.
What is the nature of cholesterol in terms of hydrophobicity?
Mostly hydrophobic.
What are androgens derived from cholesterol?
Testosterone.
What accumulates in the case of CYP 21 deficiency?
17-α-hydroxyprogesterone and sometimes Dehydroepiandrosterone (DHEA). leads to overproduction of androgens
What is Cushing Syndrome characterized by?
Chronic overexposure to cortisol.
How many carbon atoms are in the units that combine to form squalene?
30 carbon atoms (6 five-carbon units or isoprene/terpene).
What is the basic structure of cholesterol?
Hydrophobic ring system with an alkyl chain.
What are mineralocorticoids derived from cholesterol?
Aldosterone.
What is the role of ACTH in the adrenal cortex?
To produce glucocorticoids, specifically cortisol.
What hormones are unable to be synthesized due to enzyme deficiencies in CYP21 of Congenital Adrenal Hyperplasia?
Mineralocorticoids and glucocorticoids.
What metabolic condition can result from Cushing Syndrome?
Glucose intolerance, potentially leading to diabetes mellitus (DM).
What processes occur after the formation of Lanosterol to produce cholesterol?
Oxidation and ring cyclization followed by carbon removal. FORMS CHOLESTEROL
What happens when Vitamin D binds to cell surface receptors?
The receptors become activated and induce gene expression.
What property does cholesterol have due to its structure?
It is ambipathic, as it can be attached to hydrophilic groups.
What is one function of cholesterol in cell membranes?
Cell membrane stabilization.
What property can cholesterol acquire?
Can become amphipathic.
What are the two main types of corticosteroids?
Glucocorticoids and mineralocorticoids.
What does lanosterol make and what is the pathway?
Makes VITAMIN D
lanosterol —> 7-dehydrocholesterol + UV —> cholecalciferol (VITAMIN D) —> 25-hydroxycholecalciferol —> (in the liver) 25-hydrocholecalciferol —> (in the kidney) 1,25-dihydroxycholecalciferol.
What are glucocorticoids derived from cholesterol?
Cortisol.
What does aldosterone do?
Released in response to low Na/K ratio.
Stimulates Na and water uptake and K excretion.
Increases blood pressure.
What sex hormones are made from steroidogenesis?
Estrogens and Androgens
What is the primary action of aldosterone in the kidneys?
To resorb more Na+, restoring equilibrium.
What is a notable physical symptom of Cushing Syndrome?
Fat distribution in the face, neck, and trunk.
What is formed after irreversible reactions from squalene?
Lanosterol.
What hormone is released by the hypothalamus in response to stress?
Corticotropin-releasing hormone (CRH).
What condition is characterized by increased adrenal gland growth due to backup of intermediates?
Congenital Adrenal Hyperplasia.
What triggers the production of aldosterone?
A low Na+/K+ ratio.
How is dietary cholesterol digested and absorbed?
Through the lipid pathway.
What is the basic structure of cholesterol?
A 4-ring 'nucleus' + hydrocarbon chain + 3-OH (sterol)
How does cortisol regulate hormone production?
By providing negative feedback to inhibit CRH and ACTH production.
What do estrogen do?
control menstrual cycle
part of the secretory phases of uterus and mammary glands
involved in implantation and matruation of fertilized ovum
What electrolyte imbalance is associated with Addison Disease?
Hyperkalemia.
What are the corticosteroids synthesized from cholesterol?
Coritsol (glucocorticoids) and aldosterone (mineralcorticoids)
What does cortisol do?
Stress response
increases gluconeogenesis via cAMP and PKA pathways
decreases inflammatory/immune response
What are estrogens derived from cholesterol?
Estradiol.
What type of molecules are steroid hormones?
Signaling molecules.
What happens to sodium and water in urine in Addison Disease?
Loss of Na and water while retaining K+ and H+ ions due to aldosterone deficiency.
What is HMG-CoA reduced to in cholesterol synthesis?
Mevalonate.
What is endogenous cholesterol?
Cholesterol synthesized in the body, particularly in the liver.
What does CRH stimulate the pituitary gland to release?
Adrenocorticotropic hormone (ACTH).
What do androgens do?
makes testosterone mainly
stimulates spermatogenesis
promotes anabolism
What condition is characterized by a deficiency in aldosterone production?
Addison Disease.
What condition can result from deficiencies in enzymes involved in steroid synthesis?
Congenital adrenal hyperplasia (CAH).
What are some symptoms of Addison Disease related to blood pressure?
Reduction in blood pressure, lightheadedness, and loss of consciousness.
What are some mental symptoms associated with Cushing Syndrome?
Mental symptoms can include mood swings and depression.
What are sources of cholesterol?
Dietary and Endogenous
