Major Endocrine Glands and Classification of Hormones Flashcards Preview

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Flashcards in Major Endocrine Glands and Classification of Hormones Deck (23)
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what is the definition of a hormone

any substance elaborated by one cell to regulate another


in what different ways can hormones be delivered to cells

autocrine, paracrine or endocrine


what is the biologic response of a hormone generally the response of

amplification of a signal transduction cascade


what is the main control centre of the endocrine system

hypothalamus(the endocrine director)


in what ways does the hypothalamus integrate activities of nervous and endocrine systems

secretion of regulatory hormones(control anterior pituitary), synthesises hormones(transported to posterior pituitary), direct neural control(secretion of adrenaline and noradrenaline)


describe the diurnal(circadian rhythm) control of hormones

external cues(light/dark) evoke fluctuations in hormone secretion, also effected by rate at which they are eliminated from body


what type of actions can hormones have

complementary actions and antagonist actions


give an example of complementary actions of hormones

sympathetic response and the action of cortisol, adrenaline and glucagon on blood glucose levels


give an example of antagonist action of hormones

hormonal control of glucose homeostasis, (insulin and glucagon have opposing actions)


what 3 classes are hormones grouped into based on their structure

steroids(eg oestrogen/testosterone), amine-derived(eg adrenaline), proteins(eg oxytocin)


describe the properties of steroid hormones

lipids, derived from cholesterol, hydrophobic, once synthesised they are secreted, no storage, synthesis rate controls amount


how are steroid hormones transported

in blood plasma by carrier proteins(90%), or as free hormones which are biologically active


describe the general steroid hormone action

bind to nucleus receptors, an activated hormone-receptor complex forms in the nucleus, which binds to DNA + activates specific genes, results in production of key proteins


describe the transport of catecholamine and thyroid amine hormones

catecholamine = hydrophilic and unbound, 'free' in blood plasma
thyroid = bound to carrier proteins


where are amine hormones secreted from

thyroid and adrenal glands


what receptors do amine hormones bind to evoke response

membrane-bound receptors(eg ligand-gated ion channels or GPCR)


how are some amine hormones(eg adrenaline) stored

as vesicles in the cytoplasm


how are peptide hormones transported in the blood

unbound, 'free', they are hydrophilic


what glands are peptide hormones secreted by

pituitary, parathyroid, heart, stomach, kidneys, liver


what are peptide hormones synthesised as and where are they stored

synthesised as precursor molecules and stored secretory vesicles


what type of hormone are the majority

peptide hormones


what effects are provided by the binding of hormones to carrier proteins

facilitation of hormone transport, increased half-life of hormone, reservoir supply of hormone
(steroid and thyroid hormones are insoluble in plasma and need carrier proteins)


give 3 examples of important specific carrier proteins

Cortisol-binding globulin(CGB), binds cortisol
Thyroxine-binding globulin(TBG), binds thyroxine(T4), also some T3
Sex steroid-binding globulin(SSBG), binds mainly testosterone and oestradiol