intro to endocrine hormones

Question 1

definition of endocrine system

Answer 1

system that integrates + controls organ function via secretion of hormones from cells, tissues/glands, which are then carried in blood to target organs, distal to site of synthesis, where they influence the activity of target organs

Question 2

what are bodily functions controlled by?

Answer 2

endocrine and nervous system

Question 3

describe nervous mode of communication?

Answer 3

neurotransmitters (chemicals) released by neutron, act locally in synaptic cleft, not released into blood

Question 4

describe endocrine mode of communication?

Answer 4

travel via blood, hormones detected by specific receptors on target tissues - no receptor, no response

Question 5

describe neuroendocrine mode of communication?

Answer 5

nerves release hormones into blood

Question 6

example of neuroendocrine mode of communication?

Answer 6

hypothalamic-posterior pituitary axis

Question 7

can hormones have more than 1 target cell?

Answer 7

yes - can have multiple target cells, different target cells have different responses to the same hormone

Question 8

describe effect of insulin in skeletal muscle and adipose tissues

Answer 8

increases the uptake go GLC

Question 9

describe effect of insulin in the liver

Answer 9

when increased levels of GLC, there is an increase in glycogenesis - i.e.turning GLC to glycogen as storage - and a decrease in glucogenesis

Question 10

describe autocrine signals

Answer 10

cells secrete chemicals that blind to receptors on the SAME cell - not in blood and have a localised response

Question 11

describe paracrine signals

Answer 11

chemicals diffuse in ExtraCellularFluid to affect other cells - not in blood and have a localised response

Question 12

function of hormones and neurotransmitters

Answer 12

to bring about changes in activity of target cells and tissues - i.e. to increase/decrease an activity

Question 13

6 features of endocrine hormone?

Answer 13

1 - produced by cells
2 - secreted into blood
3 - transport to distal sites via blood
4 - exert effects at low conc. : x10-9 - x10-12
5 - act by binding to receptors on target tissues
6 - action is determined (-ve feedback loops)

Question 14

classes of endocrine hormone

Answer 14

peptide
amine
steroid

Question 15

describe peptide hormones

Answer 15

most common

made of amino acids

Question 16

describe amine hormones

Answer 16

derived from either tryptophan OR tyrosine

Question 17

describe steroid hormones

Answer 17

derived from cholesterol

Question 18

example of paracrine signal?

Answer 18

histamine - local site of action

Question 19

where are neurohormones released?

Answer 19

hypothalamus - a neuroendocrine tissue

Question 20

where are preprohormones (peptide) synthesised and then cleaved?

Answer 20

synthesis - ribosomes
cleaved into pro hormone - endoplasmic reticulum
cleaved by enzymes into active hormones - Golgi apparatus

Question 21

why is it useful to measure C-peptide and not insulin?

Answer 21

C-peptide shows insulin naturally produced by pancreas at that time, regardless of insulin administered

Question 22

solubility of peptide hormone?

Answer 22

H2O soluble - therefore need to bind to receptors on cell surface in order to cross membrane,
also has v fast response and dissolves easily in plasma

Question 23

what pathways do peptide hormones modulate?

Answer 23

GPCR or tyrosine kinase linked receptor pathway

Question 24

what are the 3 catecholamines and what type of molecule is each? (AMINES)

Answer 24

dopamine - hormone & neurotransmitter
norepinephrine - hormone & neurotransmitter
epinephrine - hormone

Question 25

where is epinephrine released?

Answer 25

adrenal medulla

Question 26

amines - thyroid hormones - name these 2 hormones

Answer 26

thyroxine

triiodothyronine

Question 27

how to thyroid hormones act?

Answer 27

like steroids

Question 28

function of melatonin? (AMINE)

Answer 28

regulates circadian rhythm

Question 29

where is melatonin released?

Answer 29

pineal gland

Question 30

what is the only amine hormone derived from tyrosine?

Answer 30

melatonin

Question 31

how do steroids move to target sites?

Answer 31

bind to carrier proteins e.g. albumin

Question 32

how do steroids differ to peptide/amine hormones?

Answer 32

they are made as needed - not stored

Question 33

how do steroids bind and what is the consequence of this?

Answer 33

bind to intracellular receptors -

slower onset of action and remain for a longer period

Question 34

what are the 4 tissues steroids are produced by?

Answer 34

Gonads
Placenta
Adrenal cortex
Kidney

Question 35

why is there a cross effect of steroids at high doses?

Answer 35

all have common ancestry of cholesterol

Question 36

solubility of steroids?

Answer 36

lipophyllic - therefore cross cell membrane easily

Question 37

which hormone is the active form?

Answer 37

the free hormone - only these can diffuse to target cells

Question 38

example of -ve feedback loop?

Answer 38

parathyroid hormones - Ca2+

Question 39

best way to monitor hormones in body?

Answer 39

24hr monitoring

Question 40

example of neural feedback loops?

Answer 40

adrenaline