Major Endocrine Glands and Classification of Hormones

Question 1

what is the definition of a hormone

Answer 1

any substance elaborated by one cell to regulate another

Question 2

in what different ways can hormones be delivered to cells

Answer 2

autocrine, paracrine or endocrine

Question 3

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

Answer 3

amplification of a signal transduction cascade

Question 4

what is the main control centre of the endocrine system

Answer 4

hypothalamus(the endocrine director)

Question 5

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

Answer 5

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

Question 6

describe the diurnal(circadian rhythm) control of hormones

Answer 6

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

Question 7

what type of actions can hormones have

Answer 7

complementary actions and antagonist actions

Question 8

give an example of complementary actions of hormones

Answer 8

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

Question 9

give an example of antagonist action of hormones

Answer 9

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

Question 10

what 3 classes are hormones grouped into based on their structure

Answer 10

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

Question 11

describe the properties of steroid hormones

Answer 11

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

Question 12

how are steroid hormones transported

Answer 12

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

Question 13

describe the general steroid hormone action

Answer 13

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

Question 14

describe the transport of catecholamine and thyroid amine hormones

Answer 14

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

Question 15

where are amine hormones secreted from

Answer 15

thyroid and adrenal glands

Question 16

what receptors do amine hormones bind to evoke response

Answer 16

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

Question 17

how are some amine hormones(eg adrenaline) stored

Answer 17

as vesicles in the cytoplasm

Question 18

how are peptide hormones transported in the blood

Answer 18

unbound, ‘free’, they are hydrophilic

Question 19

what glands are peptide hormones secreted by

Answer 19

pituitary, parathyroid, heart, stomach, kidneys, liver

Question 20

what are peptide hormones synthesised as and where are they stored

Answer 20

synthesised as precursor molecules and stored secretory vesicles

Question 21

what type of hormone are the majority

Answer 21

peptide hormones

Question 22

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

Answer 22

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)

Question 23

give 3 examples of important specific carrier proteins

Answer 23

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