Systems endocrinology Flashcards
What is the basic structure of cholesterol?
Has a polar head group (1), a steroid body (2) and a hydrophobic side chain (3)
Is cholesterol a hormone?
NO
What part of cholesterol makes it relatively insoluble?
Fatty tail/ hydrophobic side chain
What are the 3 main types of adrenal steriords and what is their function?
Mineralocorticoids (salt and water retention)
Glucocorticoids (glucose synthesis, protein and lipid metabolism and inflammation)
Adrenal androgens (foetal steroids and growth)
What are the 3 types of sex steroids?
Androgens
Oestrogen
Progesterones
What vitamin is also a steroid hormone?
Vit D
What do all adrenal and gonadal steroids have in common with structure?
4 rings of carbon
What is the specific modification that makes cortisol different to other steroids?
11 beta hydroxyl group
What is the specific modification that makes cortisol different to other steroids?
11 beta hydroxyl group
What is the specific difference that makes aldosterone different to other steroids
Group on 17th carbon
How do steroid hormones work and what is their time of action?
- Classic receptors in the cytoplasm get activated by steroid binding- translocate to nucleus. This causes mRNA to be made, which leaves nucleus and promotes protein synthesis at the cytoplasm
- Is a slow action- > 30 mins- 48 hours
- There is another mechanism- non genomic mechanism, steroid hormones act directly on receptors e.g. ion channels in the plasma membrane.
- This is rapid signalling, < 1 min
What makes steroid hormones more soluble than cholesterol?
A hydrophobic 6 carbon chain is removed whilst making the steroid
At what area do most steroids have a varied substituent?
C-17
What enzymes are involved in steroid synthesis?
Cytochrome P450’s
Steroid dehydrogenases or reductases
What is the function of steroid dehydrogenases and reductases?
To convert inactive forms of steroid into active forms
How is cortisol changed from its active form to inactive form?
Cortisol= active
Cortisone= inactive
What happens to cortisol levels in disease state?
Free cortisol will rise
When does synthesis of cortisol occur?
In the adrenal gland, after it has been stimulated by ACTH
Where is most cortisol converted to cortisone in the body?
The liver
What percentage of cortisol binds to proteins in the circulation?
90%
What vertebrae are the adrenal glands located at?
12th thoracic vertebrae
Where is the location and other name for the adrenal glands?
Positioned bilaterally and anteriorly on the superior poles of the kidney- triangular in shape
Also called suprarenal glands
What are the two areas of the adrenal glands and what do they produce?
Cortex= 80-90% of gland. Makes steroid hormones
Medulla= makes catecholamines
What are the two areas of the adrenal glands and what do they produce?
Cortex= 80-90% of gland. Makes steroid hormones
Medulla= makes catecholamines