Endocrine system Flashcards
what are the components of the endocrine system
pituitary, thyroid, parathyroid, adrenal glands, pancreas, ovary/testes
endocrine vs exocrine glands
endocrine –> secretions into blood
exocrine –> secretion into ducts
what are paracrine and autocrine actions
paracrine –> acts on adjacent cells
autocrine –> acts on cell which secreted hormone
water soluble hormones vs fat soluble hormones
water soluble
- travels unbound
- binds to surface receptor of interactions
- short half life
- fast clearance
fat-soluble
- travels by protein binding
- diffuses into cell for interactions
- long half life
- slow clearance
give an example of a peptide hormone
insulin, LH, FSH
what are characteristics of peptide hormones (polarity, storage and release)
hydrophilic
stored in secretory granules
released in pulses or bursts
what is proinsulin made of
C-peptide and insulin joined by cystine bonds
How does the insulin receptor work
binding of insulin to the alpha domain leads to phosphorylation of tyrosine kinase and leads to cascade reactions which drive glucose uptake
what type of hormone is dopamine
amine
what do you call thyroid hormones
iodothyronines
how is thyroid hormone synthesised and released
SYNTHESIS
thyroid follicular cells secrete thyroglobulin into colloid
iodine gets incorporated in thyroglobulin –> iodothyrosines
conjugation of iodotyrosines gives rise to T3 and T4
RELEASE
hypothalamus produces thyrotropin releasing hormone
this causes pituitary to release thyroid stimulating hormone
TSH binds to TSHR (receptor) and stimulates movement of colloid into follicular cell where T4 and T3 get cleaved from thyroglobulin
which is the active form? iodide or iodine
iodine
iodide –> dide for DEAD
how do nuclear receptor hormones work? give examples
they directly bind to DNA and affect transcription –> they function as transcription factors
Oestrogen, Thyroid Hormone, Vitamin D
what transports Vit D and How does it function as a hormone
it is transported by Vit D binding protein
it enters the cell directly in the nucleus to stimulate more absorption of calicum and phosphate
how do steroid hormones act?
diffuse through plasma membrane (hydrophobic)
bind to receptor
receptor hormone complex enters nucleus and binds to GRE
binding to a DNA region promotes transcription of that gene to mRNA
mRNA leads to protein synthesis
which hormones have a circadian rhythm
cortisol
prolactin
GH
LH
FSH
melatonin
what hormones are secreted by the posterior pituitary
oxytocin and ADH
what are the functions of oxytocin
lactation and uterus/cervical dilation
if a patient has abnormal hormonal tests what is the next test you would perform
MRI of pituitary
what are the functions of growth hormone
growth promotion and metabolism
what effect does growth hormone have on insulin and why
inhibiting –> promotes fat and carbohydrate metabolism
what effect does GH have on blood glucose
increase blood glucose
what effect does GH have on the liver and other tissues
Production of IGFs (insulin like growth factors)
leads to cell proliferation and cell growth
draw the HPT axis
hypothalamus > TRH . ant pituitary > TSH > Thyroid gland > Thyroid hormones > Target cells
negative feedback loops:
TSH inhibits hypothalamus and Thyroid hormones inhibit the ant pituitary and the hypothalamus