Co-ordination Electrical messenger

Chemical messenger

Nervous System

Neuron

cytoplasmdendroncell membranenucleusnucleus of cell which makes the myelin sheathaxondirection of nerve impulses

Nerve fiber

Myelin SheathProtection of nerve fiberSpeed up impulse transfer

Rest PotentialMore + ion outside the neroneNa K pumpK channelBig - ions

Action potential

Action potential mechanismDepolarizationStimulus to thresholdNa channel openInside nerone turn +ve.RepolarizationPotential rise inside nerone to maxNa channel closeMore k channel open so hyperpolarisedRest potential established by na k pump.

Na openK openNa closeRefractory period

ending of axon secretes a chemical which diffuses into synapse and stimulates the next neurone to pass on the impulsethe chemical is unstable and will be destroyed later

Synapse

Synapse mechanismGo

SynapticCleftNeurotransmitter in vesicle release to cleft. It diffuse to another side and attach on surface receptor. Enzyme next to receptor break down. Transmitter

Brain

Reflex arc : sensory, association, motor neurones

Peripheral Nervous Systemconsist of cranial nerves and spinal nervesthese nerves leave CNS and run out to every part of the body

Spinal Cell

Endocrine SystemHormone conceptSteroid conceptEndocrine organs

Hormone conceptHormone is chemical messenger.It required a fitted receptor.Hormone attaching to receptor calls response.

Hormone concept 2Hormone required blood vessel to transport to whole body.

Water soluble hormoneWater soluble hormone only attach to membrane receptor.

Fat soluble hormone (steroid)Steroid can penetrate cell membrane and bind to internal receptor.

Example of steroids

Feedback mechanismNegative feedback reduce hormone production when effect of hormone expressed

Endocrine and ExocrineBlood vesselSecretary duct

Endocrine organs

Adrenal glandAdrenalin

Photo of adrenal gland

Pancreas Islet of langerhans

Thyroid gland

Pituitary gland

Control of endocrine systemHormone control hormone Nerve control hormone

Anterior and Posterior Pituitary gland

Photo of pituitary gland