introduction to endorinology Flashcards
exocrine
epithelial lining forms ducts
endocrine
sheets of cells secrete hormones into the bloodstream
how is communication between glands & other tissues achieved?
but the secretion of a hormone into the blood stream & transport to a target site
how is specificity of signalling achieved?
- chemically distinct hormones
- specific receptors for each hormone
- distinct distribution of receptors across target cells
hypothalamus
highest level of the endocrine system, major centre of pituitary control
parathyroid
calcium
adrenal gland
aldosterone
testes
steroid precursors & testosterone
thyroid
thyroxine
what are the 3 main classes of chemical natural hormones?
- glycoproteins & peptides
- steroids
- tyrosine & tryptophan derivatives
which is the most diverse class of the chemical natural hormones?
glycoproteins & peptide
what does the glycoprotein & peptides class encompass?
amino acid chains of variable length, can be simple or contain disulphide bonds or be multiple chains
give an example of the glycoproteins & peptides
oxytocin
insulin
what are steroids derived from?
cholesterol
give an example of tyrosine & tryptophan derivatives
adrenaline
thyroid hormones
melatonin
describe the synthesis, storage and attitude to water of amines?
pre-synthesised stored in vesicles
hydrophilic
when are amines released from their vesicles?
in response to stimuli by calcium dependent exocytosis
how are amines mainly transported?
“free” in plasma
what’s special about the vesicles that store hormones?
usually protected from effects of that hormone
describe the synthesis, storage and attitude to water of peptides & proteins?
pre-synthesised usually from a longer precursor & stored in vesicles, hydrophilic
when are peptides & proteins usually released from their vesicle?
in response to stimuli by calcium dependant exocytosis
how are peptides & proteins transported?
“free” in plasma
what is the major trigger for the release of insulin?
the sensing of glucose in the intracellular space between beta cells of the pancreas
describe the synthesis, storage and attitude to water of steroids?
synthesised & secreted upon demand, hydrophobic
what do the stimuli of steroid synthesis increase?
increase cellular uptake & availability of cholesterol & increase the rate of conversion of cholesterol to pregnenolone
what is the rate limiting step of steroid synthesis?
the conversion of cholesterol to pregnenolone
how are steroids transported?
mainly found to plasma proteins