C1. Steroids and Hormones Flashcards
what are steroids?
A class of compounds defined by a specific
structure of 17 carbon atoms in four rings.
What are hormones?
A class of signalling molecules which regulate
physiology and behaviour in organisms.
What are steroid hormones?
A signalling molecule which has a specific
structure of 17 carbon atoms in four rings.
what are the different types of hormones?
-steroids
-proteins and peptides (Insulin, Glucagon, Oxytocin)
-amino acid derivatives (Norepinephrine, Melatonin, Thyroxine)
-Eicosanoids (Prostaglandin)
Types of steroid hormones?
-Corticosteroids (Glucocorticoids, Mineralocorticoids)
-sex hormones (androgens, estrogens, progestogens)
ONE NOTE
What is insulin?
Insulin is a peptide hormone which promotes the absorption of glucose into cells and subsequent conversion into fats such as glycogen
What is glucagon?
Glucagon is a peptide hormone which promotes glycogenolysis, converting glycogen into glucose which is released into the bloodstream.
what does endocrine mean?
Signal carried in the bloodstream.
What does paracrine mean?
Intercellular.
What does autocrine mean?
Affects the cell that secreted it.
what does intracrine mean?
Intracellular.
what is an agonist?
Activates a receptor to produce a response
What is an antagonist?
Blocks action of an agonist.
What is a inverse agonist?
Induces an opposite response to agonist.
what is a Selective Receptor Modulator?
makes up different effect in different tissues
Describe steroids
-Steroids vary by the position and
nature of the attached groups.
-Small modifications can have
huge effects on biological
activities.
steroid numbering
ONE NOTE
are steroids planar?
no
Describe cholesterol
-Forms 30% of the cell
membrane and modulates
fluidity.
-Biosynthetic precursor for:
▪ Steroid hormones
▪ Vitamin D
▪ Bile acids
STRUCTURE ON ONE NOTE
Describe steroid signalling
Glucocorticoid receptors are transcription factors that are
activated upon hormone binding. Glucocorticoid hormones activates glucocorticoid receptor.
-Glucose cortex steroid
what are corticosteroids?
A class of steroid hormones that are produced in the adrenal gland.
describe glucocorticoids
-Glucocorticoid receptors are gene specific transcription factors that are released from the cytoplasm upon hormone binding
-Affect metabolism of carbohydrates, fats and proteins.
-eg. Cortisol/Hydrocortisone
-Synthetic: Beclometasone, Dexamethasone
Describe mineralocorticoids
-Regulate electrolytes in the body by acting on ion transport in
kidneys
-eg. Aldosterone
can steroid hormones and peptide hormones enter the cell?
-Steroid hormones are generally membrane-permeable due to their
lipophilicity.
-Peptide hormones cannot enter the cell because they are too
hydrophilic.
Describe lipophilicity
-refers to the ability of a molecule to dissolve in lipids.
-In medicinal chemistry the two adjectives to describe the scale are
lipophilic (more lipid soluble) and polar (more water soluble)
Describe the troubles with lipophilicity and polarity
-If a drug is too polar, it cannot passively diffuse across the lipophilic
cell membrane.
-If a drug is too lipophilic, it is more susceptible to metabolism (and
other disadvantages).
how does a peptide hormone cause a change in transcription the nucleus?
It binds to a receptor on the outside of the cell membrane and this causes changes on the inside of
the cell - signal transduction
sex hormones?
-androgens (testosterone)
-estrogens (estradiol)
-progestogens (progesterone)
synthetic sex hormones?
-Synthetic androgens (testosterone esters, nandrolone esters)
-synthetic oestrogens (Ethinylestrogen)
-Synthetic progestogens (progestins)-
synthetic estrogens?
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