endocrinology- basic principles :0 Flashcards
examples of protein and polypeptide hormones
- growth hormones
- prolactin
- insulin
- oxytocin
these are hormones encoded by genes made up of amino acid chains of various lengths
examples of amino acid derived hormones?
- tyrosine
- adrenaline
- tryptophan
- melatonin
much smaller hormones
examples of steroid hormones?
- cholesterol
- testosterone
- oestradiol
where are steroid hormones usually synthesised?
- adrenal glands
- reproductive organs
what are the 4 main groups of hormone receptors?
- G protein coupled receptors
- Receptor Tyrosine Kinase (RTK) Families
- Receptors associated with tyrosine kinase activity
- Steroid hormone receptors
what similar features do all G-protein couples receptors share?
all have:
- an extracellular domain
- an intracellular domain
- 7 transmembrane domain
what does the extracellular domain in G protein coupled receptors do?
ligand binding
what does the intracellular domain in a G couples protein receptor do?
activates intracellular signalling cascade
what type of receptor is the insulin receptor?
receptor tyrosine kinase families
where are steroid hormones receptors usually found?
-intracellular either in cytoplasm or nucleus
what will the ability to accurately measure hormone levels depend on?
-pattern of secretion
-the presence of carrier hormones
-interfering agents
-stability of hormones
-absolute concentration
!!major determinant= rate of secretion!!
what would a raised TSH suggest?
hypothyroid
what would a suppressed TSH suggest?
hyperthyroid
why might it not be reliable to measure TSH levels in unwell patient?
their TSH levels may fall and then rise later on
would taking a random cortisol test be a good indication of HPA axis function?
no, cortisol varies so much throughout the day, it would be better to take it at 9am
-need dynamic testing to really tell HPA axis function
what is HPA axis?
-its a term used to represent the interaction between the hypothalamus, pituitary gland and adrenal glands and plays an important role in stress response
what is the formal diagnostic test for cushings syndrome?
low dose (1mg overnight) dexamethasone suppression test and if there is a failure to suppress then it is cushings
