The Endocrine System Flashcards
Regulates:
growth and development reproduction blood pressure concectration of ions behaviour
using hormones
basic principles:
- secreted from
- transported by
hormones secreted from endocrin tissues or glands intor extracellular fluid
transported by blood
endocrine receptors
on cell surface, in cytyocol, in nucleus
exert action via signal transduction
within seconds - adrenaline
hours or days - protein synthesis
3 classes of hormones:
peptide
amino acid derived
steroids
peptide hormones
- syntheisis
- secretion
- receptors
- response time
- from amino acids, usually in endocrine tissues
- secretory granules, exocytosis
- cell membrane GPCRs
- seconds/mins
amino acid dervieved hormones
- syntheisis
- secretion
- receptors
- response time
- derivatives of tyrosine e.g. adrenaline, needs specfic enzymes
- vesicles via exocytosis (excpet for thyroid hormones = use facilitated transport)
- cell surface receptors (thyroid = intralcellular receptors)
- secs/mins (thyroid = hrs/days)
steroid hormones
- syntheisis
- secretion
- receptors
- response time
- metabolites of cholesterol, needs specifc enzymes
- lipid soluble, can move across membrane (final stages of production only occur when they need ti be relased as they cant be stored)
- diffuse into cells and bind to intracell receptors
- hrs/days
7 classic endocirne glands
pituitary - in hypothalamus, anterior and posterior
thyroid - above trachea
parathyroids - posterior to thyroid (4 glands)
adrenals - cortex and medulla
ovaries
testes
endocrine pancreas - releases hormones vs exocrine pancreas = digestion
endocrine tissues = hypothalamus, kidneys, GI tract, heart, liver, adipose tissue
blurred lines - paracrine factors and neuropeptides
thyroid gland
requires iodine - essential trace element to produce pro hormone by follicular cells, stored in colloid extracellularly as prohormone until needed
when needed prohormone taken back up into follicular cells and converted into thyroid hormones - T3 and T4
exit via facilitated transport and enter interstitial fluid
hormonla actions: via nuclear receptors, regulate transcription of proteins, essential for development, growth and metabolism
parathyroid gland
contains 2 cell types: oxyphil and cheif cells
syntheises and secretes peptide hormone via secretory granules into intersitial fluid
hormonal actions = moves through blood to target -
intestines = inc Ca absorption
kidneys = inc tubular Ca reabsorption
bone = inc Ca absorption
cheif cell feedback system
if Ca is too high, receptor on cheif cells causes downstream cascade = prevents parathyroid granules from being released = negative feedback
adrenal gland
- cortex - 3 layer
1 - zone reticularis = releases steroid hormones
2 - zone fasciculata = glucocorticoid e.g. cortisol, can inc blood plasma glucose available
3 - zone glomerulosa = mineralocorticoid e.g. aldosterone
adrenal gland
medulla
chromaffin cells release adrenaline
releases catecholamines - adrenaline, noradrenaline
blood enters via artery and works way down through vessels to vein and cortisol moves down to medulla, it can stimulate chromaffin cells to make adrenaline
ovaries
cells in developing follicles of ovary produce oestrogen and progesterone
oestrogen stimulates celluar proliferation of endometrium
progesteron stimulates secretion and maturation of tissues
testes
leydig cells produce testosterone
sittmulates protein synthesis
can lead to development and growth
