steroids Flashcards
Types of steroid hormones
mineralcorticoids (aldosterone), glucocoticoids ( cortisol) Sex hormones (androgens and estrogens)
Zones of the adrenal cortex
- outermost - Z. Glomerulosa - minerals
- zona fasciulata - cortisol
- Z. reticularis - formation of DHEA
Describe the hypothalamic pituitary adrenal axis
Hypothalamus secretes Corticotropin releasing hormone which stimulates ACTH from anterior pituitary
What is androstendione
it is the precursor for the androgens and estrogens
Enzymes involved in formation of steroid hormones
- CYTp450 SCC
- 3 b hydroxy steroid DH
- 17 (alpha) OH
- 21 OH
- 11 B OH
Mechanism for LH and FSH
G protein coupled - adenylate cyclase
which pathway do growth hormones use?
Jack Stat - associated with TYR K
Effects of growth hormone
1) increase lipolysis
2) protein synthesis
3) Increase glucose
Has direct effects on tissues and indirect effects due to the liver producing IGF-1 which acts on tissues too.
what causes prolactin to be produces
- The absence of dopamine (prolactin inhibitory hormone)
2. Thyrotropin releasing hormone from hypothalamus (prolactin releasing hormone
which molecules are agonists
Angiotensin and vasopression
What decreases ca
calcitonin which is produced by Parafollicular (c cells) of thyroid G
what increases ca
- vitamin D3 and parathyroid hormone
Actions of parathyroid
-Bones -osteoclasts
Kidneys - absorb more ca
- Small intestine - reabsorb more can but u need vitamin D3
What is the role of the kidney in regards to calcium
it activates vitamin D into its more active form (Calcitriol) also is involved in reabsorbing more ca if ca levels are low
Pro-opiomelacortin
a Precursor polypeptide made in pituitary which will give rise to polypeptide hormones such as ACTH.
Which carbons do you start hydroxylating for aldosterone and cortisol
C- 17
A- 21
Structure of thyroid gland
1 unit is called a follicle, cells are called follicular cells and lumen has colloid
which enzyme changes the oxidation state of iodine
Thryoid peroxidase (from I- to 0)
How do t3 and t4 get to their target cell
immunoglobulin binding protein
which pumps/channels are involved in thyroid hormones?
- NA/I symporter
2. NA/K pump
Differences between T4 and T3
t4 can only be made by the thyroid gland, but t3 can come straight from t4 by deiodination using deiodonase (selenium). T3 can also come from the thyroid gland. T3 is the biologically active form- every cell only has receptors t3. t4 is produced in majority!
Functions of t3/4
- uncouplers - free oxidation UCP thermogenin
- increase metabolic rate
- increase HR
Hyperthyroidism
- Fast HR
- Sweating
- lose weight
- restless
- graves disease can be cause by hyperthyroidism, bulging eyes
treatment: Carbimazole
relationship between t3/4 and insulin
antagonists because they increase glucose levels.
Thyroid hormes and DNA
Thyroid hormone receptor is a type of nuclear receptor that is activated by binding a thyroid hormone. TRs are transcription factors which are typically associated with retinoic acid receptors forming heterodimers.
