endocrine receptors Flashcards
endocrine
autocrine
paracrine
what is a hormone
any substance elaborated by one cells to regulate another cell via autocrine, paracrine, or endocrine route
how does the hypothalamus integrate nervous and endocrine activities together
- secretion of regulatory hormones
controls activity of anterior pituitary hormones - synthesis of hormones
- direct neural control function
what is the endocrine director
hypothalamic control
T/F external cues such as light/dark evoke fluctuations in hormone secretions
T
there is diurnal control of hormone levels
other than circadian rhythm what else influences hormone levels ?
the rate at which they are eliminated by the body
what are the 3 classes of hormones
steroids - cholesterol backbone eg oestrogen
amine-derived eg adrenaline
peptides eg oxytocin
what are steroids
derived from cholesterol
synthesis rates control the amounts
they are not stored
lipophilic > so are transported in the blood by binding to carrier proteins > then the free/unbound steroids are biologically active
what are amine hormones
hydrophilic
are transported unbound in blood plasma
however thyroid amines are bound to carrier proteins
they are derived from amino acids
secreted from thyroid and adrenal medulla
stored in vesicles in the cytoplasm
what are peptide hormones
vast majority
hydrophilic and are transported unbound in blood plasma
secreted by pituitary, parathyroid, heart stomach liver and kidneys
held together by disulphide bonds
what does cortisol binding globulin bind
cortisol in a selective manner
what does thyroxine binding globulin bind
thyroxine (T4)
what does sex steroid binding globulin bind
testosterone and oestradiol
