Principles of Endocrine Disease and Its Assessment Flashcards
what are the three level the endocrine system split into?
primary - end organ
secondary - pituitary
tertiary - hypothalamus
what are the types of endocrine disease?
hyper-functioning
hypo-functioning
eu-functioning
what is the role of the hypothalamus?
integration of signals and conversion of them to a chemical messenger
what amplifies signals from the hypothalamus?
pituitary gland containing hormones that get diluted and travel around the body
where do the hormones act?
end organs
what do end organs do?
switch off production of the central hormones = negative feedback
why is the area around the pituitary important?
the hypothalamus is above then there is the optic chiasm and pituitary stalk. These structures get compressed if there is a tumour
what is the cavernous sinus?
its just below hypothalamus containing cranial nerves supplying extra-ocular muslces.
what happens if the extra-ocular muscles are squished?
double vision and loss of sight from compression of optic chiasm
how can you see the hypothalamus?
from a saggital section with the pituitary fossa sitting on top of the sphenoid sinus
what do hormones act as?
receptors: surface or nuclear
what is different about peptide hormones?
they are charged and act as surface receptors
what are steroid hormones like?
they are aliphatic (fat soluble) so act on nuclear receptors
what is most hormone release like?
pulsatile and varies during the day
what is a dynamic test?
shows meaning of the two extremes shown in a one off blood test
apart from causing secretion from target hormone what else do hormones do?
cause growth of the target organs. therefore the target organ shrinks if hormone taken away
what is principle of endocrine testing based on?
law of mass action
how is endocrine testing carried out?
coloured dyes. Radioactive Immunoassay (RIA)
how is RIA carried out?
we have a binding site, usually an antibody and then the hormone. Forms an equilibirum in a test tube, so there will be some bound horomone-antibody and some free.
there is a radioactive tracer bound to the hormone
how do you measure the RIA results?
- make sure every binding site is full of the marker
what is the first stage of measurment?
- construct a curve of known amounts of un-labelled hormone which will displace labeled hormone and drop the radioactivity
how do we assess the radioactivity?
via centrifuge. the bound stuff falls to the bottom and you measure the radioactivity in there. unknown samples are then compared
what are the two types of assays used?
- total hormone assay
- free hormone assay
total hormone assay
cheap, easy but have physiological problems as in plasma most hormone is bound to a binding protein (designed to protect hormone from enzymatic breakdown until reaches target site)
