Summary Biology OCR A: Hormonal Communication (A*)

14 HORMONAL COMMUNICATION
systemuseshormonesto
Endocrine sendinformationaboutchangesintheenvironmentaroundthebodytobringabouta coordinated
response


TheEndocrineSystem
made
upofendocrineglands
ENDOCRINEGLAND group
ofcellsspecialisedtosecretechemicalsknownashormones
directlyintobloodstream
examples ofendocrineglandspancreasandadrenalgland
pituitaryGlandmaster
gland
at ofthe
base brain
thereleaseofotherhormones
makesseveralhormoneswhichinturncontrol
hormonalresponses arecloselylinkedandcoordinated
hypothalamusensures nervousand
closeproximityto




EXOCRINE GLANDS Secrete chemicalsthroughductsintoorgans ortothesurfaceofthebody

Hormones
chemicalmessengers thatcarryinformationfromone
partofthebodytoanother
Theycanbe
steroids

proteins amines
glycoproteins tyrosinederivatives

Whenarehormonesdirectlysecretedintobloodstream
changein concentrationof a particularsubstance
anotherhormone
impulse

Oncesecreted thehormones aretransported inthebloodplasma all overthebodyThehormones
diffuseoutofthebloodandbindtospecificreceptors forthathormonefoundonmembranes orcytoplasm
ofcellsintargetorgans
TARGETCELLS

, TypeofHormone determineseffecton a targetcell

STEROIDHORMONES

lipidsoluble
passthroughlipidcomponentofthecellmembrane andbindtosteroidhormone receptors
thisforms HORMONERECEPTORCOMPLEX
receptorsmaybepresent incytoplasmornucleus depending on hormone


hormonereceptorcomplexacts as a transcriptionfactorwhichthenfacilitatesorinhibitsthe
transcription ofaspecificgene
example Oestrogen

NONSTEROIDHORMONES
thecellmembrane
hydrophilic cannotpassdirectlythrough
theybindtospecificreceptors onthecellsurfacemembraneoftargetcell
triggersacascadereactionmediatedbychemicalscalledSECOND MESSENGERS

example Adrenaline

Hormonal V Neuronal

Hormones areslowed and lessspeafic comparedtoneuronalcommunication
because hormonesnotdirectly released intotargetcells
Hormones havea ungerlastingandwidespreadefted

notbrokendown asquickly as neurotransmitters