Chem Basis: Steroids 1
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Chem Basis: Steroids 1
Chem Basis Steroids
Chem Basis: Steroids
Chem Basis: Steroids
The Steroids are a group of substances of ______________origin.
both plant and animal
All steroids possess what characteristics?
Tetracyclic backbone/skeleton derived from cyclopentanohydrophenathrene
Among the steroids are substances of very considerable medicinal importance such as:
________________may be considered the starting point with some of it synthesized in the cortex from acetate.
Some cholesterol used in steroid synthesis in the adrenal cortex is derived endogenously from what?
__________________ probably represents the major source of cholesterol for the biosynthesis of the various steroids.
Exogenous dietary cholesterol
Corticosteroids are classified into two groups, what are they?
What are the Adrenocorticoid hormones?
Describe the Hypothalamic/pituitary control of Glucocorticoids:
: CRF (corticotrophin releasing factor)
: ACTH (adrenocorticotropic hormone)
: Synthesizes and releases GC
What is the general action of GCs in the peripheral tissues?
Production of glucose from non-sugar sources
Inhibit the use of glucose in the tissues
Describe the physiological control of Mineralcorticoids:
Octapeptide angiotensin II
Stimulates synthesis of permease called
: antiduiretic-induced protein (AIP)
What is the general action of MCs in the peripheral tissues?
REtation of Na
K and H excretion
Maintain blood volume
What group of patients should MCs be avoided in?
What group of patients requires supplementation of MCs?
Describe how Glucocorticoids and mineralocorticoids act on the receptor/cell?
Pass through cell membranes into the cytosol and bind to intracellular receptor proteins
Form a steroid-receptor complex
Translocation to nucleus
The portion of MC or GC receptors that binds to _____ is highly conserved, and looks the same regardless of receptor type.
The domain that binds the ________ is different from one type of steroid to the next.
GC receptors are believed to interact with which face of the glucocorticoid structure?
MC receptors are believed to interact with which face of the mineralocorticoid structure?
What general effects are Corticosteroids used for?
____________ activity of corticosteroids is considered undesirable therapeutically.
What are the general therapeutic uses of Corticosteroids?
How do GCs have Anti-inflammatory activity?
GCs stimulate the synthesis of Lipocortin, which inhibits phospholipase A2
PLA2 cleaves AA from Phospholipids resulting in inflammatory prostaglandins
What diseases are treated by the anti-inflammatory effects of GCs?
How do GCs inhibit the immune system?
Inhibit Interleukin-1 (IL-1)
Impacts proliferation of B-lymphocytes
Inhibits activation of T-lymphocytes
Decreased IL-2 production
TNF is decreased
In what group of patients should Immunosuppressant GCs be avoided in?
Those with an infection
How do GCs prevent allergic activity?
Inhibit synthesis and release of histamines
Why do GCs need weaning during D/C?
Hypothalamic-Pituitary-Adrenal axis suppression occurs with use
Under what conditions do you not need to wean patients off of Glucocorticoids?
Short treatments of 7-10 days
What are the side effects of GC therapies?
Increased infection risk
Increased K secretion
Increased Ca excretion
Describe the basic skeleton structure which steroid hormones are derived from:
Tetracyclic (four rings, three cyclohexane and one cyclopentane)
What is the most stable conformation, chair or boat, of cyclopentanoperhydrophenanthrene?
What is a sterol?
Cyclopentanoperhydrophenanthrene w/ hydroxyl groups
What is a sterid?
Cyclopentanoperhydrophenanthrene basic hydrocarbon structure
What is a Steroid?
Cyclopentanoperhydrophenanthrene w/ more carbonyl groups
All steroids have one or two angular methyl groups at what locations?
C13 and or C10
: C18 (at C13) and C19 (at C10)
Some steroids have an additional carbon chain attached at what point?
Under what conditions can a steroid have a two carbon chain at 17 Beta?
Must have C13 and C10 methyls
What are the two carbons attached at 17 Beta named?
C20 and C21
Which is the A ring?
Which is the B ring?
Which is the C ring?
Which is the D ring?
In the corticoids and sex steroids, the A/B ring fusion and the C/D ring fusion are most commonly ______________, making the entire steroid structure very flat.
What is the allo conformation of a steroid?
A/B is trans (C/D is also trans)
What is the “Normal” conformation of the steroid?
A/B is cis (C/D is still trans)